Tag Archives: condensation

Post Frame Condensation and Insulation Challenge

Solving Yet Another Post Frame Condensation and Insulation Challenge

Long time loyal readers will sigh as yet another post frame building has been erected without thoughts to how to properly insulate and control condensation. Had our new friend invested in a Hansen Pole Building, chances are good we would not be having this question and I would have had to write about something else today! Our Building Designers follow with these recommendations: https://www.hansenpolebuildings.com/2019/11/post-frame-building-insulation/.

Our new friend COREY in POST FALLS writes: 

“I have a 36×48 pole building with trusses on 12’ with BCDL 5psf, the roof is plywood sheeted with composition roofing with ridge vent and gable vents. The wall Purlins are on the exterior of the poles and there is no vapor barrier. I would like to install a ceiling with insulation and insulate the walls. I am looking for vapor barrier and insulation recommendations. Was thinking of installing 2×4 on 24 centers to bottom of trusses and installing OSB and blown in insulation, and then framing in between poles adding batt insulation and sheeting with OSB, but am unsure of controlling vapor. Thank you.”

Mike the Pole Barn Guru responds:

Small world, many years ago I graduated from Post Falls High School!

A vented ridge relying upon gable vents as an air intake is usually very inefficient. You should make sure your vents in each end are located in the top half of your attic and have at least 415 square inches of net free ventilating area on each end. This means you are probably going to have to add more vents. Effective ventilation of this area is essential to preventing mold and mildew in your attic.

Wall girts flat on column exteriors are inadequate to carry imposed loads and will not meet deflection limitations. I would suggest you reinforce each of them to create either an “L” or a “T”. Assuming you have 6×6 wall columns, you could place a 2×8 bookshelf style girt on top or bottom of each girt, nailing through 2×8 into existing girts with a 10d common nail at say 12 inches on center. This will create an insulation cavity and allow for easy interior finish.

For ceiling joists between your trusses, 2×4 will not be adequate you should use 2×6 #2 with joist hangers on each end.

Unless you have a Weather Resistant Barrier (https://www.hansenpolebuildings.com/2016/01/determining-the-most-effective-building-weather-resistant-barrier-part-1/) between framing and wall steel, my recommendation would be to have two inches of closed cell insulation spray foam to the inside of wall steel. Then fill balance of wall cavity with BIBs insulation: https://www.hansenpolebuildings.com/2011/11/bibs/ with a well sealed vapor barrier towards the inside space.

Post Frame Building Insulation

Pole Barn Guru’s Ultimate Guide to Post Frame Building Insulation

When it comes to insulating any building (not just post frame ones – like barndominiums) there is a certain point of diminishing returns – one can spend so much they will never, in their lifetimes, recoup their investment.

Here my ultimate guide to post frame building insulation is based upon practicality and obtaining the best possible value for investment.

There are some basics applicable to any steel covered building:

Under any concrete slab on grade inside a building, place a well-sealed vapor barrier. Read about under slab vapor barriers here: https://www.hansenpolebuildings.com/2017/11/vapor-barriers-slabs-grades/.

Between roof framing and steel roofing – please do not assume condensation is not going to be a problem. At some point in time it will become one and if precautions are not taken regrets will happen. Condensation under roof steel is maybe number one of the issues I am asked to assist with.

Least expensive financially, but does take some extra labor hours, especially if it is windy – a single air cell layer reflective radiant barrier. Six foot widths will install much quicker than four foot. Make sure to order with a six foot width NET COVERAGE and an adhesive tab along one edge with a pull strip. Without an adhesive tab all butt edges will require seam tape, not expensive, but adds lots of time. Do not waste your money on adding an extra approximate R 0.5 for double bubble (two layers of air cells).

For a slightly great investment in materials, hours of labor can be saved by the use of an Integral Condensation Control bonded to roof steel. This would be my product choice. https://www.hansenpolebuildings.com/2017/03/integral-condensation-control/.

Next higher cost would be sheathing the roof with either OSB (Oriented Strand Board) or plywood on top of roof purlins. Roof purlins will need to be spaced appropriately so sheathing seams fall on purlins (16, 19-3/8 or 24 inches on center). Roof truss top chord live load must be increased to allow for greater dead loads. Either 30# felt (asphalt impregnated paper) or an Ice and Water Shield must be placed between sheathing and roof steel. Roof screws must still be placed to go into purlins, as thin sheathing is inadequate to adequately hold screws.

Bigger financial investment, but no extra labor involved is to have two inches of closed cell foam sprayed on the underside of roof steel. This will prevent condensation and is noise deadening. As a rough budgetary figure, plan upon spending roughly two dollars per square foot of roof surface.

Storage/Utility Buildings

If you ever believe anyone might ever have a future desire to climate control your building then provisions should be made for making it easiest to make future upgrades.

For now we will assume this building is totally cold storage. If it might ever (even in your wildest dreams) be heated and/or cooled include in your initial design, walls with a Weather Resistant Barrier (https://www.hansenpolebuildings.com/2016/01/determining-the-most-effective-building-weather-resistant-barrier-part-1/) between framing and siding. 

Taking walls one step further would be ‘commercial’ bookshelf wall girts (https://www.hansenpolebuildings.com/2011/09/commercial-girts-what-are-they/).

In roof – have trusses designed to support a ceiling load, ideally of 10 pounds per square foot (read about ceiling loaded trusses here: https://www.hansenpolebuildings.com/2016/03/ceiling-loaded-trusses/). 

Trusses should also be designed with raised heels to provide full depth of future attic insulation above walls (https://www.hansenpolebuildings.com/2012/07/raised-heel-trusses/).

Make provision for attic ventilation, by having an air intake along sidewalls using enclosed ventilated soffits and exhaust with a vented ridge.

Any overhead doors should be ordered insulated – just a good choice in general as, besides offering a minimal thermal resistance, they are stiffer against the wind.

Equine Only Use

Same as storage/utility however ventilation is essential (and often overlooked). (Read more on stall barns here: https://www.hansenpolebuildings.com/2012/08/stall-barn/)

Garage/Workshop/Man Cave/She Shed/House/Shouse/Barndominium

Many previous recommendations are going to be repeated here. Ultimately it is going to depend upon willingness to include higher R values in initial budget, rather than having increased utility bills forever.

Start with a Frost-Protected Shallow Foundation – post frame version (https://www.hansenpolebuildings.com/2016/11/frost-protected-shallow-foundations/) with sand on the inside rather than a thickened slab. This makes for an excellent and affordable design solution.

For walls, we will again work from generally ascending price and R values.

On low end would be having installed a weather resistant barrier beneath wall steel, in conjunction with commercial bookshelf wall girts. Fill insulation cavity with unfaced batt insulation and cover inside face of wall with a well-sealed six ml clear visqueen vapor barrier. As an alternative to fiberglass would be mineral wool insulation as it is not affected by moisture (https://www.hansenpolebuildings.com/2013/03/roxul-insulation/). This method can be entirely done D-I-Y.

I have personally used BIBs (https://www.hansenpolebuildings.com/2011/11/bibs/) in several buildings, including my current barndominium home. It does require a certified installer.

A Weather Resistant Barrier can be eliminated by the use of a ‘flash coat’ of two inches of closed cell spray foam against the inside of wall steel. Balance of wall cavity can be filled with batt insulation. (https://www.hansenpolebuildings.com/2016/07/advantages-spray-foam-over-batt-insulation/).

For added R value and a complete thermal break, add two inch rigid closed cell foam boards to inside of framing. To maintain thermal break integrity, glue foam boards to inside of framing and properly seal all seams. Gypsum wallboard can be glued to the face of foam boards.

After ceiling has been installed, have insulation blown into dead attic space, following Energy Star™ guidelines (usually R-45 to R-60).

My Barndominium Windows Are Leaking

Common questions we hear from barndominium, shouse (shop/house) and post frame home owners are, “Why are my new windows leaking?” or “Why do I have condensation inside of my windows?” In fact, many new barndominium owners think their windows are defective and need to be replaced in an effort to cure this problem. To answer these questions, let’s review what causes window condensation.

Condensation is visible evidence of excess air moisture. It may appear as water, frost, or ice on window or door surfaces. This occurs more frequently during winter months because of extreme differences between inside and outside air temperatures. Warmer air holds more water meaning air in any given room center will hold more water than air adjacent to window or exterior door walls, since this area is always cooler. When warm, moisture laden air moves toward cooler window or door walls, it becomes cooler and cannot hold as much moisture as it held when it was warmer. This moisture is dropped and appears as water on glass and frames of windows and doors.
Windows do not cause condensation, they just happen to be where moisture is most visible. Condensation is a sign of excess moisture in barndominiums. This can be caused by temporary conditions such as:
Building materials contain a great deal of moisture. As soon as heat is turned on, this moisture will flow out into the air and settle on door and window glass. This will usually disappear following first heating season. During humid summers, houses absorb moisture. This will be apparent during the first few weeks of heating and then should dry out. Sharp, quick, and sudden drops in temperature especially during the heating season will create temporary condensation problems.

Condensation can also be caused by more permanent conditions:
Insufficient attic ventilation and/or soffit ventilation traps moisture in barndominiums. Having sufficient soffit vents to allow adequate air flow in and ridge vents for exhaust will allow moisture and humidity to escape. Excessive humidity may be a result of poor ventilation but can also be a result of an imbalanced heating and air system or a need to add additional ventilation. Inadequate (or missing) vapor barriers under concrete slabs on grade. While Building Codes require a vapor barrier under any concrete slabs in heated buildings, it is all too often overlooked.

Controlled ventilation and elimination of excessive indoor moisture can keep humidity within bounds. Here are some suggestions to help reduce indoor moisture:
Turn off or set back furnace humidifiers until sweating (condensation) stops. Remove pots of water on radiators or kerosene heaters. Use exhaust fans or open windows slightly in kitchen, bathroom and laundry room during periods of high moisture production such as cooking, taking showers, washing and drying clothes. Clothes dryers must be vented outside. Do not hang clothes to dry indoors. Waterproof concrete floors. Make sure attic vents are unobstructed. Place all house plants in one sunny room where the door can be kept shut and avoid over watering. Opening windows slightly for a brief period of time will allow humid air to escape and drier air to enter. Use a properly sized dehumidifier, to reduce humidity.
Excessive indoor humidity and moisture are not a result of your windows. You should view the amount and severity of window condensation as a clue moisture damage may be taking place inside walls or ceiling cavities of your barndominium. This can lead to rotting wood, deteriorating insulation, and blistering paint.

Roof Trusses 4′ o.c., Condensation Issues, and a Sliding Door

This Monday the Pole Barn Guru answers questions about roof trusses at 4′ o.c., ways to solve condensation issues, and sliding door options.

DEAR POLE BARN GURU: My question is I just purchased some roof trusses that are 32 feet long heel to heel they are constructed with 2 by 4s can I put these on 4 foot centers? Thanks. CRAIG in BELVIDERE

DEAR CRAIG: You can if you want your building to collapse in a moderate snow event. Along with your trusses, you should have received an engineer sealed truss drawing with all specifics as to what can be carried by it and spacing. If you did not, and they are prefabricated metal connector plated wood trusses, there should be a manufacturer’s stamp somewhere on truss bottom chords. You could then contact them and give them truss specifics (and probably a few photos showing lumber grades, web configuration and steel connector plate sizes. From this, they may be able to determine what you have actually spent your hard earned money on.

If you are unable to determine where they came from, another alternative would be to take their information to a Registered Professional Engineer with roof truss experience. For a few hundred dollars, you may be able to get an opinion as to their strength.

 

DEAR POLE BARN GURU: Hello, I have a 30x46x16 all steel pole barn that I am having condensation problems with. My question is what is the best thing I can install or do to help the problem? I have been told by others to install a ventilation exhaust fan controlled by an thermostat. I do have electricity in barn. I also have a wind turbine I haven’t installed yet too? Should I put both of these items in or one of them? And if so, do you guys install these items? Please help, its rusting all my tools and growing mildew in my RV!! Thanks ALYSSA in LEWIS CENTER

DEAR ALYSSA: You have found a challenge (one of many actually) Quonset steel building providers never seem to mention – condensation (read about other Quonset issues here: https://www.hansenpolebuildings.com/2011/07/quonset-huts/).

The two best things you can do are to seal your concrete floor (https://www.hansenpolebuildings.com/2019/02/how-to-properly-apply-post-frame-concrete-sealant/) and have two or more inches of closed cell spray foam insulation applied to the inside of your steel building shell. An exhaust fan might help, provided it can adequately move enough air (need to move between 3000 and 4000 CFM – cubic feet per minute) and it will require an air inlet of similar dimensions. We are not contractors, so we won’t be able to assist you with any installations.

 

Figure 27-5

DEAR POLE BARN GURU: Hi. Not really looking for a whole building. What I am looking for is an exterior sliding door to install onto a shop wall. The Shop is a timber frame unit. The opening is roughly 6 feet wide by 7 – 7.5 feet tall. I have not yet taken exact measurements. I will as soon as I can find a vendor within my price range.

I was very intrigued by your video presentation describing the “nail on” round track system. Also, this shop is in an odd location. It is a basement shop under my house, the house is built on a slope, so the wall I want to put the door onto is at ground level, but the opposite wall is fully underground. Since it is an exterior door to my basement any info on weather sealing for the cold Vt. Winters would be greatly appreciated. ANDREW in WESTMINSTER

DEAR ANDREW: Whilst I can appreciate you thinking a sliding “barn style” door might be a solution, I am doubtful as to it truly being a viable design solution. At best a sliding door will be a challenge to insulate beyond a bare minimal R value. A bigger concern is you are not going to achieve a tight air seal.

A design solution I can recommend (although it may stretch your budget) would be to go with an insulated commercial steel double entry door (six feet wide) in steel jambs. These doors will afford a secure access to your shop, are insulated and can seal air tight.

Although we typically only provide doors with our complete third-party engineered post frame building kit packages, you can message Materials@HansenPoleBuildings.com for a delivered price.

 

Exhaust Fan to Reduce Pole Barn Condensation Issues

Post frame (pole barn) building condensation problems are a re-occurring theme. With proper design and planning, condensation should not occur, however more often than not this is a penny wise, pound foolish event – caused by post frame building providers (either builders or vendors) not advising new building owners of possible challenges.

Reader JEFF in MICHIGAN writes:

“Hi Mr. Guru. I have a 1 year old, 2400 sq.ft. pole barn at my northern MI home. The barn is a wood frame, well insulated, drywalled, and Hardi board exterior barn with asphalt shingles. I’m not sure of a vapor barrier under the concrete floor, it was poured before I saw it.

I have 2ea. 56k BTU “standing pilot”, ventless heaters (no electricity required) to keep the inside temp above freezing (45-50*) in the winter for boat storage and occasional projects. I went powerless because this is more of a summer home at this point and I’m not up there much in the winter. If there’s a power outage, my barn will stay warm. 

That being said, I have a condensation problem. I’m thinking a louvered, 24″ exhaust fan running through a humidistat switch and an intake grill on opposite ends of the barn should cure the issue. I’m looking for verification that this will fix my problem before I buy the fan and cut holes in the walls or if maybe you have another, simple solution.

Thanks for your help.”

Mike the Pole Barn Guru writes:

For those unfamiliar with “standing pilot”:

A standing pilot is a standard ignition device for most natural gas burning heating systems, and has been for many years. It’s a continuously burning flame at heater bottom, responsible for starting burners actually generating heat for a post frame building. Though it’s a widely used technology, there are a few things giving it a less-than-stellar reputation.

Standing pilot lights are actually fairly simple in design. A gas line terminates in a small burner, where the flame is created. A bit of composite metal wire, called a “thermocouple,” connects the burner to a gas line valve. When the pilot light is lit, thermocouple registers heat and generates an electric current. This current travels down thermocouple to the gas valve and opens it. This is what keeps the pilot light burning. When the pilot light goes out, thermocouple’s electric current stops and gas valve closes. This is a safety measure to prevent gas from flooding your home.

Most common problem for standing pilot lights is the light going out. This tends to happen because the flame is unprotected from air currents or sudden draft. Though there is an ignition system on most heaters to relight the pilot light, other issues can occur.

Thermocouple for pilot light often wears out over time, eventually losing the ability to create an electrical current. This can occur from wear and tear, corrosion, becoming detached from volt meter, or simply becoming bent way from pilot flame. Regardless of how thermocouple stops working, the pilot light is unable to stay lit. If your pilot light seems to light without issues, but almost immediately goes out, it’s because thermocouple is no longer keeping gas valve to flame open.

Jeff’s starting point should be to eliminate, or at least minimize where moisture is coming from. Place a wrench on your floor overnight, if a dark impression remains on floor (sort of like chalk body outlines at murder scenes) when removed you know you have no vapor barrier underneath your slab. Seal your floor.

Next culprit is your heaters. You’ll want to read more here: https://www.hansenpolebuildings.com/2019/02/how-to-reduce-condensation-in-post-frame-buildings/.

Whether your proposed exhaust fan will be adequate or not will be dependent upon its CFM (cubic feet per minute) capabilities. You will probably want to plan for around 10 air exchanges per hour. If you have a 14 foot high ceiling, then 40 x 60 x 14 = 33,600 cubic feet X 10 times / 60 minutes per hour = 5600 cfm.

I hope this helps, and good luck!

Pole Barn Guru Blog Review

This is the third year the Pole Barn Guru blog has been in competition for the Best Construction Blog. Last year this blog was second in the world, tying for first in quality, however losing the popular vote. Part of this process is a review of each blog by Mark Buckshon of Construction Marketing Ideas (www.ConstructionMarketingIdeas.com).

Below is Mr. Buckshon’s review:

Hansen Buildings’ Pole Barn Guru: Practical information about post frame (pole barn) structures

By Mark Buckshon

 –March 23, 2019

The Pole Barn Guru is currently leading in the 2018 Best Construction Blog’s popular vote and unless there is a surprising surge from supporters of another blog by the popular vote’s conclusion on March 31, this blog will probably earn the popular vote win status.

There are reasons for this support — the blog combines depth and focus as a “go to” resource for post frame (pole barn) buildings; and it doesn’t avoid the challenges with these low-cost structures, often used for outdoor storage and as rural outbuildings.

I’ve been reading some posts, for example, dealing with issues relating to condensation and insulation, some initiated by questions from outsiders — that is folks who have a pole barn structure not provided by Hansen.

Rather than brushing off these external inquiries with a: “Hey, that’s not my problem” attitude, this blog provides some practical answers, even as it indicates the issues probably wouldn’t have been problems if they had been considered in the initial design and purchase.

That educational aspect makes this blog truly worthy.

Consider, for example, this question in a recent blog post:

Hello! 

I have a pre-existing pole building that I am having a ton of trouble with. It is partitioned into two rooms, the back room is heated to around 50F. The attic space/loft space has a lot of condensation and I cannot seem to get this fixed. I have tried a lot of solutions, none of which have worked. I know that you build these types of buildings so I am hoping that you can recommend someone who might be able to come in and look at this issue and help me with a solution that works. I have no idea what to do next and I am a local business owner – my business is at a standstill right now until I can get this issue fixed. If you can recommend any general contractor, or anyone who might have expertise in pole buildings who I can contact I would greatly appreciate it. 

Thank you so much!”

The question is posed after a brief introduction:

Long time readers should be thoroughly drenched with solutions to condensation issues by now. As post frame construction has moved off farms and into suburbia, climate control has brought with it a plethora of condensation challenges.

So, what are the answers?

To control your condensation challenge you need to either remove warm moist air from inside your building, prevent this air from becoming in contact with surfaces at or below dew point, heat and/or ventilate. Here’s a brief summary, followed by solutions specific to your case: https://www.hansenpolebuildings.com/2019/02/how-to-reduce-condensation-in-post-frame-buildings/.

If you do not have some sort of thermal break below your pole building’s roof steel – two inches of closed cell spray foam should be applied. This process will be best done by a professional installer. Make certain to not block ventilation intake and exhaust points.

Unless you know for certain a vapor barrier was placed under your building’s concrete slab, seal the floor.  https://www.hansenpolebuildings.com/2019/02/how-to-properly-apply-post-frame-concrete-sealant/ 

and https://www.hansenpolebuildings.com/2018/11/siloxa-tek-8505-concrete-sealant/.

Vent any dead attic spaces. https://www.hansenpolebuildings.com/2018/03/adequate-eave-ridge-ventilation/.

Heating your building to a temperature above dew point will also solve this issue. Avoid heating with propane, as it adds moisture to the air.

Now in my opinion, that sort of detailed, practical advice shows how an effective, consistent and useful blog can provide real value to clients and potential customers alike (and serve a general community purpose, even for people who will never purchase a thing from Hansen.)

This value translates to search engine effectiveness and of course a reputation for knowledge and service. If you are thinking about purchasing a post frame structure, for example, I’m confident after reading through the relevant blog postings you’ll have the confidence to ask the right questions and share the site/usage observations to ensure that the structure serves its purpose and problems such as condensation or poor insulation don’t occur in the first place.

Unvented Post Frame Attics

Unvented Post Frame Attics

Energy efficiency concerns have literally become a “hot” (pun intended) topic in new construction, and post frame construction methods are no exception to inclusion. Traditionally buildings have had insulation placed or blown into dead attic spaces, directly above a ceiling. Unvented attics have entered fray as an alternative.

 

To construct an unvented attic, air-impermeable insulation (think closed cell spray foam) will be applied in direct contact with steel roofing (or sheathing) underside and gable end walls so as to tie roof insulation into wall insulation below. Moving insulation boundary to the roof deck underside allows temperature and humidity conditions in the attic to be reasonably close to those of the conditioned building interior.  No attic floor vapor retarder or insulation should be installed with an unvented attic assembly.

Closed cell spray foam insulation products meet code requirements for use of an air-impermeable barrier applied to underside of roof. This prevents air infiltration and limits accumulation of airborne moisture in the attic. Using closed cell spray foam insulation applied to underside of roof deck eliminates a need for alternative methods of condensation control such as reflective radiant barriers or CondenStop (https://www.hansenpolebuildings.com/2014/07/condenstop/).

In hurricane or wildfire prone areas wind-driven rain or embers cannot enter an unvented attic assembly, as there are no vents.

Spray Foam

Vented attic designs originated in cold climate areas. In these cold climates, attic ventilation is commonly used to remove warm, humid air from attic spaces. Air leakage from conditioned spaces below a ceiling greatly increased likelihood of moist air entering attics. Without adequate attic ventilation, the underside of the roof deck can have condensation form and interior heat can cause roof surface snowmelt leading to ice damming.

Use of venting to control moisture in cold climate attics comes with some inherent challenges. In high snowfall areas, snow accumulation and drifting can often block ridge vents. This limits venting and increases potential of damage due to ice damming, roof leaks and condensation.

Closed cell spray foam does not come without added upfront investment costs, however some of these can be mitigated in materials and/or labor savings.

Considering climate control of your new post frame building? If so, an unvented attic may be a viable solution worth investigating.

 

A Case for Minimum Post Frame Truss Loads

A Case for Minimum Post Frame Truss Loads

Portions of this article were written specifically for Component Advertiser, a monthly truss industry publication. However I feel strongly enough about this subject to use my column to pitch it to both my employers and other post frame building kit suppliers and contractors.

In my career I have done about everything imaginable when it comes to post frame (pole) building trusses. I have been blessed to have been able to spend a better portion of over two decades working within or owning prefabricated MPCWT (metal plate connected wood trusses) manufacturing facilities. I have designed, engineered, fabricated and delivered trusses. As a builder, I raised my first set of post frame trusses nearly 40 years ago and many more have followed.

I have also been a provider of post frame building kit packages across most of my adult life. Our industry (post frame buildings) is one where low price, rather than service and quality, drives most sellers and buyers. Sellers, more often than not, have not learned well how to convey value of benefits they offer – instead they live in fear of being a five-spot more than their competitors when it comes to price.

For nearly seven years I have been writing a weekly advice column, “Ask the Pole Barn Guru™”, where I answer post frame building oriented questions from anyone. One repeatedly asked question is in regards to adding ceilings to existing post frame buildings. Most roof trusses for these buildings were not designed to support ceiling loads, generally due to a fear of increasing building price.

Many post frame buildings are constructed in areas where pole buildings are exempt from building permits, or there are little or no structural plans reviews done. This contributes to an attitude of “make it cheap” by encouraging use of minimal loads for trusses.

A great majority of post frame buildings are used as residential accessory buildings – garages, shops, RV parking, man caves, she sheds, etc. Nearly all of these buildings have truss spans of 40 feet or less, so my proposal for voluntary minimum loading requirements for post frame buildings will be directed towards these structures.

Why not apply these minimums to larger span structures? Many wider span buildings are going to be used as horse riding arenas or equipment storage for farming and are never going to have ceilings in them. Costs to design for greater loads, for spans of 50 feet and greater could result in some significant costs. Wide span buildings being used for more humanly occupied (and therefore more critical in protection of human life) purposes are likely to have a Registered Design Professional (architect or engineer) involved, who will specify roof loads based upon building use and function.

In areas of minimal or no snow, with Pg (ground snow load) values of under 20 psf (pounds per square foot) Top Chord Live Load (TCLL) should be fixed using a minimum of 20. For areas where white stuff has a greater possibility of occurrence 25 psf appears to be a reasonable minimum.

Most post frame buildings have light gauge steel roofing over purlins. Hopefully they also have some sort of minimal weight material between these to minimize or prevent condensation issues. In most instances, total dead loads required in order to support truss weight, condensation control, purlins and roofing will be less than 2.5 psf. There are folks who have ideas not always shared with truss designers – like using OSB or plywood sheathing between purlins and roofing. Also, rooftop solar panels are becoming more and more popular and find their way onto more than a few roofs not designed to support their weight.

My proposal (again for buildings of 40 foot spans and less) would be for a minimum TCDL (Top Chord Dead Load) of five psf. While this does not solve every possible case, it does allow for greater end user flexibility.

Traditionally, most post frame buildings did not have ceilings installed, so a very minimal BCDL (Bottom Chord Dead Load) has been used. Most typically a one psf loading will be selected, more than covering bottom chord lateral bracing and limited lighting. However, as post frame have moved from farms to suburbia, more buildings are getting interior finishes – meaning ceilings. I like to use 10 psf, in cases where I am designing for a drywall covered ceiling with insulation above, however even five psf would handle most ceiling loads.

Load duration – no snow, I am good with 1.25, snow areas 1.15. However, in my humble opinion, if TCLL exceeds 50 psf, chances are snow will be piled on top of these trusses for more than two months across structure’s lifetime and a DOL (Duration of Load) of 1.0 will be most appropriate.

A hidden side benefit to establishing these voluntary minimums will be stronger trusses able to withstand more abuse in handling. Some lumber members will be larger dimension or higher grade material and steel connector plates will increase in size. All of these factors increase probabilities of reduced truss damage.

Hansen VisionNow, I believe, time has come to stop selling price to post frame building clients and sell benefits. Safety becomes easiest to sell – no one wants to live with a fear of their building collapsing and injuring them, their loved ones, or destroying their valued possessions. Flexibility in future use – also an easy sell, if a future building owner decides they want to add a ceiling they can safely do so.

Minimum post frame truss loading benefits all, by raising the overall quality of finished buildings  with a negligible investment.

How to Properly Apply Post Frame Concrete Sealant

How to Properly Apply Post Frame Building Concrete Sealant

Condensation in post frame buildings can be problematic. In order to reduce condensation probabilities, minimizing water vapor sources proves to be paramount. Concrete slabs, especially if no vapor barrier was placed beneath them, are a prime source of water vapor. Proper application of sealant can greatly reduce or eliminate water vapor transmission from slab into the building.

Concrete sealant will make your concrete more resistant to weather exposure, water, grease and oil stains, abrasion and deicing salts. What’s more, they will help to make it easier to clean. But in order for a sealer to work its magic, it must be applied properly. Each step, from surface preparation to choosing right application method for product, will have a big impact on final outcome.

Following are some tips for applying concrete sealer properly. Whichever brand of sealant you use, be sure to follow specific instructions recommended by product manufacturer, since they may differ from general guidelines given here.

When you apply sealer can be important as well. Allow new concrete to cure completely (28 days or more, as recommended). Most sealers must be applied under dry conditions, since applying sealant to damp concrete could cause haziness or loss of adhesion. Air temperatures are also important and should typically be above 50°F during and for 24 hours or more after sealer application. Always allow sealer to dry completely before exposing it to foot or vehicle traffic. Drying times before exposure to heavy traffic can be as long as three days.

Surface preparation before applying a sealant will be extremely important. All oil, grease, stains, dirt, and dust must be removed or they may prevent sealer from adhering properly. Some manufacturers recommend etching surface first with an etching solution to ensure best adhesion.

Two most common methods of applying sealant to concrete surfaces are by roller or sprayer, often depending upon whether choosing a solvent or water based sealer. Always refer to manufacturer’s specific application guidelines.

Regardless of application method always strive for maximum coverage. Typical coverage rate should be 250 to 300 square feet per gallon, depending upon concrete porosity. Most important rule to remember – it’s best to apply two thin coats, making sure sealant doesn’t puddle or form uneven, thick areas. When applying a second coat of sealant, apply it in opposite direction (or perpendicular) to first coat to ensure even coverage. Wait to apply second coat of sealant for 24 hours or time recommended by the manufacturer.

 

Foil Insulation is Not Insulation

Foil Insulation Is Not Insulation

Products being incorrectly marketed and sold as “foil insulation” are actually nothing more than a radiant reflective barrier. They are not insulation. I have previously covered this very subject, so will not rank and rail more: https://www.hansenpolebuildings.com/2014/04/reflective-insulation-wars/

Today’s learning article has inspiration in this from reader BOBBY in GRASSTIN who writes:

“I have a 24×36 Morton Pole building built in early 80s. I am trying to insulate and heat the building. Currently I have ridge vent and soffit vents. I was not intending on putting a ceiling under the trusses. This fall I lined the whole building roof and walls with foil insulation and hung 2 natural gas infrared heaters as a temp fix. I currently have two 9×7 overhead garage doors which are un-insulated and leak pretty much on all sides and a sliding door on the table end which leaks. Needless to say my gas bill is atrocious and because I sealed the ridge vent and soffit vents with foil I have a bad condensation problem mostly because the heaters put out so much water. Aside from sealing the doors with new insulated doors, how should I tackle the insulation and the condensation problem? Do I spray foam the roof and leave the vents plugged? Or spray foam the roof and install ceiling and unblock the soffit and ridge vents? Or spray foam ridge and soffit vents and install Gable vents? Which would probably be cheaper than a ceiling. Would I lose all my heat out of the Gable vents? Newbie here and appreciate the help.”

Mike the Pole Barn Guru responds:

Lots of things happening here, so let’s dive right in.

Ditch your current heaters and replace them with vented units. There are efficient vented gas heaters available, providing same type of heat you are used to, but they exhaust all their combustion by-products outside through a wall vent. You’ll lose not only water vapor, but also carbon monoxide, nitrogen dioxide and other contaminants.

Use a high quality sealant over your building’s concrete floors: https://www.hansenpolebuildings.com/2018/11/siloxa-tek-8505-concrete-sealant/.

So far we have eliminated sources of most condensation, moving next to how to best insulate what you have.

Chances are very small your building’s trusses will support a ceiling. This would have been an ideal case, as it would have kept you from having to pay to heat an area above truss bottom chord level.

Replace your present overhead and sliding doors with insulated overhead doors. Tear out foil “insulation” and throw it away. Keeping eave and ridge vents sealed, use closed cell spray foam insulation across walls and underside of roof deck. An absolute minimum thickness will be two inches, providing approximately R-14. You will need to weigh benefits of greater R values against investment.

Me – if allowed by my Planning Department I would build another building properly designed to be energy efficient. Chances are it will be comparable in investment to what you are going to throw into a three decades old building, plus it will be brand new!

 

A Steel Ceiling, Wall Finishes, and Condensation

Today Mike addresses questions about steel ceilings, options for wall finishes, and condensation in added space.

DEAR POLE BARN GURU: I have a 40ft wide x 60ft long x 12ft high pole barn. The trusses are 4ft on center. I want to put a steel ceiling up and wanted to know the best size piece to use when putting it up. 8, 10, or 12. MICHAEL in TABERNACLE

DEAR MICHAEL: Before consider this move confirm your trusses are designed to support added ceiling weight across bottom chords. Also, make certain to adequately ventilate dead attic space you will be creating (read about adequate ventilation here: https://www.hansenpolebuildings.com/2018/03/adequate-eave-ridge-ventilation/).

Having satisfied above, if you intend to merely attach steel panels to truss undersides and run panels lengthwise, I’d go with 28’ and 32’ long pieces to minimize splices. If framing has been placed between trusses to support steel running across building, go with full length panels and have no splices.

DEAR POLE BARN GURU: Hello.

We have a new pole building and are looking at options for finishing the interior walls. The building has been well insulated and will have a heater and AC unit. Besides drywall, what other options are available? LISA in MIDDLETOWN

Finished Pole Building InteriorDEAR LISA: Gypsum wallboard (sheetrock) will certain be most common as well as most popular option. If you go with 5/8″ thick Type X, it will also be fire rated. You can use any material for covering walls one would find in any type of building – however most of them are still installed over sheetrock. If for a shop building, 7/16″ OSB proves to be quite popular. Some people like steel liner panels, however I find them difficult to attach things like shelves and cabinets to and they get dented.

 

DEAR POLE BARN GURU: Greetings.  I have a 20-year old 40×25 post and beam barn, 2 story, shiplap siding, with metal roof and concrete floor.  Last summer I walled off a 11.5×25 area for a workshop (10ft ceiling) and noticed a lot of condensation this past spring (after pouring the concrete floor last fall). The workshop is used sporadically from spring through fall. I would appreciate your advice on how to address condensation issue and any recommendations for insulation.  Thanks for your time. RALPH

DEAR RALPH: Your increase in condensation most likely comes from moisture leaving concrete as floor cures. If you placed a good vapor barrier properly under slab, it should eliminate this as a source of moisture for condensation. If you did not, then you will want to seal slab with a high quality sealant. If condensation issues continue, it may be necessary to add a powered exhaust vent. Click here for further reading about insulation for different post frame uses: http://www.hansenpolebuildings.com/2018/06/pole-barn-insulation-part-ii/

 

 

 

 

 

Will My Post Frame Building Support a Ceiling?

Will My Post Frame Building Support a Ceiling?

One of my frequently received questions – wanting to add a ceiling into a post frame building and wondering if the building will support the added weight. Other frequent questions include condensation issues and ventilation, so this reader has hit upon a trifecta.


Reader BRYAN in SWANTON writes:

“I am having some condensation issues. And I was curious about insulating the building. Also wanted to ask if my building is able to have a ceiling installed. Thanks for the fast reply.”

 

 


By any chance have you recently poured a concrete slab-on-grade inside of your building? If so, until concrete fully cures, it will expel a great deal of moisture inside of your building. Solution – open your doors to allow moisture to escape and keep them open until condensation issues no longer exist. Read more here: https://www.hansenpolebuildings.com/2018/01/condensation-roof-steel/.

 

If you poured a slab without a well-sealed vapor barrier underneath, it will contribute to excessive moisture challenges. If no vapor barrier, top of slab should be sealed: https://www.hansenpolebuildings.com/2018/11/siloxa-tek-8505-concrete-sealant/

 

Your new post frame building and its trusses were not ordered to be able to support the added weight of a ceiling. It may be possible to upgrade your trusses with an engineered repair to be able to carry a bottom chord dead load of five psf (pounds per square foot) or more. Plan upon an investment of $295 (plus sales tax if applicable), even if a truss repair cannot be designed. Contact Justine at justine@hansenpolebuildings.com if you are interested in going this route.

If you are able to get a repair to install a ceiling, this newly enclosed attic area will need to be adequately ventilated. This may be a possible solution: https://www.hansenpolebuildings.com/2018/07/my-pole-barn-needs-ventilation/

In order to insulate, best solution (although costly) may be to use closed cell spray foam insulation. If you purchase an insulation kit for your overhead door, you will need to change out door springs in order to handle the added weight.

 

 

Pole Barn Moisture Issues

Moisture from condensation can be a major issue in initially poorly thought out pole barns.

Reader MATT in SHAKOPEE writes:

“Hi. I am having issues with moisture in my pole barn. It is getting to the point that mold is starting to show up on the walls and cement floor. The barn is about 28 x 36 with 12 foot walls. It has a service door and two 10 foot over head doors and 4 windows on the south wall. The ceiling is tinned, insulated and has a vapor barrier. The floor is cemented and I am unsure if the floor has a vapor barrier. The walls are not insulated or tinned.

The barn is used for storage right now cars, mowers, tractor, etc. The barn is unheated and sometimes the doors stay shut for one to two weeks. We have gone through and cleaned what seems to be mold off the walls but are unsure on how to stop the moisture issue. Wonder if some kind of exhaust fan would help? Or if you have any suggestions? Any help would be greatly appreciated.”

Mike the Pole Barn Guru writes:

I’d start with trying to eliminate moisture source. If you leave a wrench lying upon your building’s concrete floor for a few days and return and  a dark spot appears below where the wrench was placed, your building has no under slab vapor barrier. If this occurs, use a good concrete sealant across floor. This in itself might resolve problems – watch the steel wall siding insides and see if they stay dry after sealing.

If this does not resolve problems, then you need ventilation. I will surmise your building does not have enclosed vented soffits and a vented ridge. Can’t go back and correct lack of overhang issues now, but you can add gable vents – a minimum of 242 square inches net free ventilation area in each endwall with vents located in top half of each gable.

Location of your building should also be examined. If soil around building exhibits signs of being moist, you need to make sure grade will allow water to drain away from building. It may be necessary to trench around building and add a drainage system to move water away from your building. Gutters should drain water sufficiently distant from building as well.

If nothing else works, here’s how to determine power ventilation requirements: https://www.hansenpolebuildings.com/2018/07/my-pole-barn-needs-ventilation/.

 

 

 

Examining a Light Steel Truss Frame Building

Examining a Light Steel Truss Frame Building

I have never owned or assembled a light steel truss frame building. A gentleman named Stan Floyd worked for me as a salesman when I owned M & W Building Supply. Stan’s dad had fabricated light steel truss frame buildings in Arkansas and Stan was interested in developing this concept in Oregon and Washington. With my blessing Stan founded Web Steel Structures in Sandy, Oregon and found out things weren’t quite like they had been in Arkansas – where building permits, if even required, were issued far more liberally. Northwest jurisdictions required engineering for both frames and buildings, as well as a need for a higher degree of control over welder competency.

Reader DEBORAH in OMAHA writes:

“Did pic come through?

Does this look viable at 30+ years old?

Tear down? I’m looking at buying this property and I’m wondering if I’m going to be the one tearing this 180’ x 85’ building down…

There are only 4 bolts holding the truss frame together at center. Bays are 18’ on center. Every other bay has a criss cross bracing with wire (X) that is of steel cable – somewhat loose. I think there is another cross at the ceiling in kind of a strange place.

I believe the purlins are 2 x 8 as opposed to 2 x 10 which might be better. Building is in Southern IL near KY border.

I think this may have been a Cuckler kit. But I’m not sure. I’ve contacted Star Buildings to see if they know.

Thoughts?

I called an SE for a site visit and load calc and I know that will be about $12,000. It would be estimated as steel quality is unknown. Site visits for just a nod are about $900.”

Dear Deborah ~

Thank you very much for sending photos.

You are looking over a light steel truss frame building – not a post frame building. I am not a gambling man, however I would wager there was no actual engineering done for this structure to start with. Light steel truss frames, such as this, are also rarely engineered. More often than not, frame designs are just like daddy used to do them, so they must be good. Well, engineering does not quite work like this.

Some observations from your photos – minor discolorations appearing as “runs” down sides of roof purlins are due to condensation. No steel roofed building should be constructed without some sort of mechanism to minimize condensation. Only realistic fix for future condensation control would be to have closed cell spray foam insulation placed below roof surface. This insulation should be a minimum thickness of two inches and in most areas a going rate of about a dollar per square foot, per inch of thickness. You could be seeing a $30,000 bill.

Purlins with major blackness have mold due to roof leaks. This mold can be removed, but will prove to be labor intensive. I’d replace any roof ‘skylights’ with steel panels. If they have not yet begun to leak, they will in time.

Unless roof purlins are some grade higher than #2 & btr, they are over stressed in bending and likely have deflection issues. Chances are good wall girts have similar challenges.

In summary, if you decide to invest in this property I would recommend you not go inside this building when snow sticks to roof or winds are over 50 miles per hour. Insure it heavily (for non-depreciated replacement cost) and don’t keep expensive horses inside it.

For history buffs – Cuckler Building Systems division of Lear Siegler Inc. (LSI), was purchased by Star Manufacturing Company in 1986. With manufacturing locations in Monticello, IA and Turlock, CA, Cuckler had annual sales of approximately $20 million. Cuckler Steel Span Company had previously been acquired by LSI in 1970. I’d be interested in any stories about Cuckler Steel Span’s earlier years.

 

Avoiding Condensation When Insulating an Existing Pole Barn

Avoiding Condensation When Insulating Existing Pole Barn

The last thing people want to have to deal with would be condensation dripping in their pole barn. When an originally unheated cold storage building becomes repurposed to be climate controlled, possible condensation poses some new challenges.

If you are reading this article and plans are to construct an unheated building, I implore you to consider taking steps so it could be repurposed to be heated and/or cooled later. Please browse through some of my previous articles regarding this subject, such as: https://www.hansenpolebuildings.com/2018/06/pole-barn-insulation-oh-so-confusing/.

Reader JOSEPH in ALPINE writes:

“We have a pre-existing pole barn that we want to turn into a insulated building. Knowing that condensation would be a problem, I’m looking for a professional to consult with so it is done correctly. Is this something you do and what are your rates?

 

The building is 15×15, on a pad. There is no attic- 1/4” plywood is nailed to the ceiling 2x4s. We’d like to keep this height since it affords space for a loft. There is a single central roof vent. I read your response to one customer about using unbatted insulation on the walls and punching holes in the plastic to allow venting. But how does one allow for venting when there is no attic space? Our main house (1937 farm home, remodeled to modern code in 2003) is a metal roof with the upstairs rooms opened up, no attic, no roof vents. How can one replicate what is done in the house with this pole barn?

Thanks.”

Mike the Pole Barn Guru writes:

I am deeply flattered to have someone offer to hire me for a consultation. Here is my response to Joseph:

I am a bit geographically inconvenient to be able to come and see your building. However, based upon experience and what I would do if it was my own building, I will give you some free advice. You are welcome to use it, or discard it as best you see fit.

As you do not know if a vapor barrier exists beneath your existing concrete slab, I would use a high quality surface sealant over it. Your major water source for potential condensation will be through this slab. I’d close off roof vent, and have inside surface of siding and roofing closed cell spray foamed. Your local installers can give you recommendations for thickness, however I would not go with less than two inches thickness. If possible or practical, unfaced fiberglass insulation may be added to the inside to increase R value. However, it might be most practical to just pay a little extra for thicker spray foam.

 

 

Cold Storage Pole Barns

Post Frame Cold Storage for Fruits and Vegetables

Hansen Pole Buildings’ Designer Rachel passed along this:

“Have a client call in asking if we have experience in designing a building for cold storage.  Confused I said yes, many building are used for cold storage and are not insulated or heated.  He said no I mean COLD storage as in storing fruits and vegetables in 36 or 38 degrees.  He is wondering what we would suggest for insulation and what he should consider when designing the building.”

Detached cold storage buildings are constructed with a sole purpose of producing or storing goods in low temperatures. Think of them as typical heated buildings turned inside out. Instead of keeping heat in during cold weather, they keep heat out during warm weather.

Condensation problems can be huge, if not properly dealt with. Adequate and totally sealed insulation plays a huge part in preventing condensation. Exterior walls should have a Weather Resistant Barrier between framing and wall steel to allow moisture to pass out of wall. Dead attic spaces should be well ventilated with eave air intakes and ridge exhaust vents.

Among most critical consideration for cold storage will be selection of a method for insulating the facility. Effective insulation will minimize cold transfer to exterior and reduce operating costs. Recommended cold storage building envelope (shell) insulation values are R-30 in walls and R-40 for roof. Concrete slab should be insulated to R-20. Recommended method of insulation will be polyisocyanurate (Polyiso). Polyiso has an R value of approximately six to 6.5 per inch of insulation, so a minimum of five inches of Polyiso recommended for walls and 6 ½ to 7” in ceiling. It should be glued on, as through fasteners will transmit heat and condensation could form upon exposed heads. It is essential for joints to be sealed and a vapor barrier should be placed between insulation (insulation goes inside of framing) and wall girts and ceiling joists.

Failure to totally seal interior vapor barrier can result in Polyiso insulation gaining as much as 15 times its own weight from absorbed moisture.

Special consideration needs to be given to site preparation, in order to minimize possibility of frost heave.

Building access should be through a wide 14 foot tall insulated overhead door in each endwall. Industry standard storage bins are four feet square and three feet tall. Bins can be stacked five high, leaving room for mechanical equipment above with a 20 foot interior clear height.

 

Allowing space for equipment movement and free airflow around each stack of pallet bins approximately 215 pounds of product can be effectively stored for every interior square foot of building.

And there you have it…a cold pole barn!

Radiant Barrier, Wind and Hail, and Sliding Door Parts?

Mike answers questions about a adding radiant barrier, wind and hail, and parts for sliding doors:

DEAR POLE BARN GURU: I have an existing pole barn and want to add a radiant barrier to the inside walls before I insulate and cover the walls. Is this wise and can I use a foil that comes in a roll. Once attached there would be a 1 and 1/2 inch air space between the foil and the metal. 

Thank you for any advice you would have with this. CANDICE

DEAR CANDICE: This would not be a good idea as you are creating a space between two vapor barriers in which condensation could occur and moisture problems develop. Your best bet is to remove the steel siding, one wall at a time, install a well sealed building wrap (like Tyvek), then reinstall the steel.

 

DEAR POLE BARN GURU: We get a ton of wind and hail throughout summer months. How will pole barn hold up to these conditions? REBECCA in PEYTON

Aerial ViewDEAR REBECCA: Here are quick links to your answers:

Wind: https://www.hansenpolebuildings.com/2011/06/more-high-wind-news/

Hail: https://www.hansenpolebuildings.com/2011/09/steel-roofing/

 

DEAR POLE BARN GURU: Good morning. We have a Miracle Span Quonset, would you have 10 x 14 sliding doors that would fit it? KRISTEN in BRAINERD

Farm Storage BuildingDEAR KRISTEN: Thank you very much for your interest. We do have sliding doors which would fit, however due to shipping challenges we only provide them with the investment in a complete post frame building kit package. We would suggest you visit the ProDesk at your local The Home Depot®.

 

Fire Resistance, Condensation, and Wind Speed

Fire Resistance, Condensation, and Wind Speed

DEAR POLE BARN GURU: Do you know if WMP-10 metal building insulation facing is ok to have exposed in a commercial building in regards to its fire resistance rating? JON

DEAR JON: WMP-10 facings are flame resistant, however you should consult with your local building code enforcing agency to determine if they will allow it to remain exposed given your use of the structure. An alternative might be Johns Manville FSK-25 faced batts which are laminated with an FSK (foil-scrim-kraft) facing, which enables the insulation to carry a fire hazard classification rating of 25/50 or less per ASTM E 84. The FSK-25 facing also serves as an excellent vapor retarder and may be left exposed where codes permit. The FSK-25 batts are a lightweight fire-resistant thermal and acoustical fiberglass insulation made of long, resilient glass fibers bonded with a bio-based binder.

Personally, I’d look at using unfaced fiberglass or rock wool batt insulation then covering the interior surface with 5/8″ Type X gypsum wallboard. Probably less expensive and would afford greater R-values with less of an investment.

 

DEAR POLE BARN GURU: I recently had a small pole barn constructed in Northern NJ which I’m about to insulate. Needless to say, the information regarding this is very confusing. The end goal here is to not have a condensation problem. With no insulation on the walls currently the metal walls sweat. The roof consists of metal roofing on top of “double bubble” on top of purlins with ridge vent and soffit vents.  The walls will be filled with 6″ fiberglass and a poly vapor barrier applied. The ceiling will either be OSB or gypsum attached to the bottom of the trusses with blown insulation on top with no vapor barrier. With that said, my question is with this configuration, will the gable ends above ceiling height sweat or do they need to be insulated? If so what would be the recommended insulation?

Thanks, CONFUSED in NEW JERSEY

DEAR CONFUSED: With proper ventilation in your attic I won’t say it will be impossible to have condensation on the inside of the attic gable endwalls, however the probability should be small. If you want to make certain, an inch of closed cell foam can be sprayed on the inside of the endwall steel and it will eliminate any chance.

DEAR POLE BARN GURU: Are your plans for stick built frames or CBS frames or both? If only for frame built what is the wind ratio? SUNSHINE in JUPITER

DEAR SUNSHINE: Our buildings are neither stick built or concrete block – they are post frame buildings.

Since January 1973 anemograph stations within the United Kingdom have tabulated for each clock hour the mean hourly speed and the maximum gust (of approximately three second duration). The ratio of maximum gust speed to the mean speed for individual hours as an effective height of 10 meters is referred to as the gust ratio. The mean wind ration is the ratio of the extreme gust speed to the extreme hourly mean speed, both having a return period of 50 years. This ratio turns out to be 1.60.

Here in the colonies, we design using Vult (Ultimate Wind Speed). Until the 2012 IBC (International Building Code) we designed for Vasd (Allowable Stress Design) which is 60% of Vult.

One of the beauties of post frame construction is the buildings can be designed to support any wind load situation needed.

Building a Pole Barn House

Reader JEREMY writes:
“Good Morning and Happy New Year!
We are currently in the process of building a house inside a pole barn, and have noticed condensation on the inside walls and roof when we heat it.  We do not have any vents installed yet, and would like to know if the condensation will stop after we get the walls/insulation/sheetrock put up and vents added to the attic.  We are very concerned about this issue, so any advice you can give will be greatly appreciated by our family J!

enclosed overhangsHere are a few details about our current building:
-No vents to the outside yet, but plan to install venting in the attic soon.
-Regular R-panel metal roof and walls installed on wood runners hanging on treated wood posts.
-Concrete slab floor that has been poured for about 2 years
-Bubble wrap insulation between metal outside and wood runners-not sure of r-value or details and it seems to be sealed well
-When heating we are using an old propane central heating unit, but did not have exhaust on the heater ran to the outside so thinking that could contribute to the condensation
-also use a wood stove to supplement heat when we are out in the building working
Let me know what you think when you have time, and thank you!”
Jeremy ~

Mike the Pole Barn Guru 

My first guess is there is not a well sealed vapor barrier under your concrete slab. if not, things which will help – make sure ground around your building is sloped away at at least a 5% slope for 10 feet or more. If you do not have gutters, get them. Have downspouts discharge at least 10 feet away from the building. If excess water is still present, it may be necessary to install drain tiles around the perimeter of your building.

If you have not insulated the perimeter of the slab, do so. Follow the guide for Frost-Protected Shallow Foundations (https://www.hansenpolebuildings.com/2016/11/frost-protected-shallow-foundations/).

Seal the surface of the concrete slab.

Take off the steel siding, remove the reflective radiant barrier from the walls and install a quality building wrap (like Tyvek), then put the siding back on. The barrier is keeping moisture in your building, whereas a building wrap allows moisture to exit. Completely fill the wall cavities with insulation. Place a well sealed vapor barrier between framing and gypsum wallboard to be installed on the walls. Do not place a vapor barrier between the ceiling drywall and the roof framing above.

Install fully vented soffit panels along the eave sides and a continuous ridge vent.

Tear Down to Rebuild? Bay Spacing, and Condensation Problems

DEAR POLE BARN GURU: Hello, I am going to tear down a 30x40x10 pole building to rebuild on my property. I noticed that the trusses are spaced 10 feet apart and are set on the 6×6 pole that has been notched. With no header board. This is an all metal building. Was wondering if this is an acceptable method of notching the post to put trusses on. Thanks. SHAWN in INDUSTRY

DEAR SHAWN: The most typical engineered post frame design provided by Hansen Pole Buildings utilizes a double (two ply) prefabricated wood truss notched into the columns (most usually spaced every 12 feet). This, in my humble opinion, is a combination which provides the best possible truss to column connection for post frame buildings, along with the reliability of the double truss system.

I would have concerns about the reassembly of a tear down, due to possible materials damage, as well as the building possibly having been designed to a no longer valid building code. My recommendation would be to contact the original engineer of record for advice as to how to proceed. If you are unable to contact him or her, then a local RDP (Registered Design Professional – architect or engineer) should be engaged to determine the structural integrity of the building as well as its adequacy to support the given climactic loads under the current building code.

DEAR POLE BARN GURU: Hello again! I reread the instructions and it said for immediate response to leave email. So I posted it above. Hello Pole Barn Guru! Wishing you a blessed day. My question is about a studded wall with double trusses. What I am trying to do is avoid having to build a 14 ft wall to accommodate a car lift. I am building a 30×50 shop. The garage doors will be on the 50 side. My thinking is build stud walls and frame in laminated posts to resemble a 6×6. They would be set at 10 widths to accommodate a 10×10 garage door. This way I could set the trusses and have open overhead bays between the trusses to accommodate the car lift and not have to build 14 ft walls. Would the idea of double trusses work in this type of build? TONY in ATHENS

DEAR TONY: If you are starting from scratch, why not just construct an engineered post frame building and columns and double trusses approximately every ten feet? I say approximately as a 10 foot width residential overhead door requires roughly 10’1″ of width between the columns. We can design a building for you, which would not have bottom chord bracing between the trusses in the bay where the overhead door would fall – thus allowing for extra headroom for your car lift. You will certainly get the most for your building investment by using post frame design.

In the event you are already constructing some other sort of building, you should consult with the Registered Design Professional (RDP – registered architect or engineer) who designed your building, as he or she would need to make the appropriate alterations to ensure the structural adequacy of what you have in mind.

In any case, for the sake of safety, do not attempt to do design work on your own – entrust it to a RDP.

 

DEAR POLE BARN GURU: I have a pole barn in Colo Springs.   I have pretty bad ceiling condensation in the winter.  The prior owner just stuck R-36 up there.  I am thinking of removing each roof panel and putting Rufco Vapor Barrier and putting the metal roof panels back down. 

I would prefer to do it inside with a radiant barrier but that will probably not work.  Any suggestions?  Something better than Rufco?  Thank you. FRANK in COLORADO SPRINGS

Reflective InsulationDEAR FRANK: On your existing building – while Rufco is an excellent vapor barrier, it will not stop condensation issues, as it does not provide a thermal break. If the prior owner installed the batt insulation in the plane of the ceiling, I would recommend the use of closed cell spray foam on the underside of the roof steel. This would eliminate having to remove and reinstall the roof panels. If this is your only option, Hansen Pole Buildings does provide a reflective radiant barrier in six foot net coverage widths with a tab on one side with an adhesive pull strip for easy sealing of laps. You might give this a consideration.

 

Condensation Solutions, A Ceiling the Right Way, and Timing

Advice about condensation, ceilings done right, and the timing of questions

DEAR POLE BARN GURU: My deck roof is metal panels on 2×4 purlins, rafters are 2×6, like a pole barn. I am enclosing it, and need to stop the condensation. I spray foamed it with closed cell, but there is some condensation on the foam in a few places. It will be covered with drywall. Would a 6 mil plastic vapor barrier on the conditioned side work? MICHAEL in FRAZIER’S BOTTOM

DEAR MICHAEL: Provided you are able to reduce the moisture content within the building so as no vapor is being trapped between the vapor barrier and the foam, it should take care of the problem. In all reality, as long as you have no holes in the gypsum drywall, once it is painted you should have eliminated the problem of condensation against the insulation.

Now getting to the real problem – you have too much moisture in your building. If you did not place a well sealed vapor barrier under your concrete slab floor, you need to seal it. Walls also need a vapor barrier (without holes) on the conditioned side to prevent moisture from passing through.

 

DEAR POLE BARN GURU: I have a 40 x 80 pole barn with 8 foot truss spacing. I will be installing faced rolled insulation between each truss. What is the recommended ceiling product to install on the inside? Wood, metal, that will be lightweight and easy to install?? Thanks JEFF in SYCAMORE

DEAR JEFF: I see problems in your future….

Faced insulation is the absolute wrong product to use for insulating your ceiling. Any insulation placed at the truss bottom chord level should be unfaced. The best bet would be to blow insulation in above the finished ceiling.

In any case, you must adequately vent the attic space.

Now, on to the ceiling.

 

I am hopeful you have trusses designed with a minimum of a five psf (pounds per square foot) ceiling load, with 10 psf being even better. Confirm with your RDP (Registered Design Professional – architect or engineer) who designed your building, however 2×4 #2 ceiling joists at 24 inches on center between the bottom chords with joist hangers should adequately support a ceiling.

My choice of ceiling product?

5/8” Type X gypsum wallboard. It is affordable, weighs under three psf and provides fire resistance.

 

DEAR POLE BARN GURU: I’m putting up a building with a 3/12 pitch single sloped roof. radiant reflective polyethylene, vapor barrier insulation between the purlins and the metal roof sheathing. Probably rock wool batts under the 1-3″ draped barrier. Do you think the roof has to be vented, and how would this work? CHRIS in BROOKLINE

DEAR CHRIS: Yes, it would need to be vented and it is my feeling you are going about this entirely in the wrong direction. Your question is well timed, as I have just written an article on how to properly insulate between purlins, which will be posted soon. The basic gist is your best solution is to use closed cell spray foam applied directly to the underside of the roof steel.

 

Commercial Girts Best for Drywall, Site Prep, and Condensation

DEAR POLE BARN GURU: I’m considering a pole barn for my residence but had a question about the girt placement between posts. I read in the FAQ section that they are placed like shelves between posts. Would it be possible to mount drywall directly to these for interior walls without additional bracing or building of interior wall frames? I’m trying to avoid framing an entire building within a building, it seems pointless and not cost effective. If I need to frame every interior wall to hold drywall and insulation, I can simply build a standard stick frame house. VAN in INDEPENDENCE

Installing Drywall on CeilingDEAR VAN: Bookshelf girts for insulation (e.g. Commercial Girts) is a quick and easy way to create a deep insulation cavity as well as providing the framing for your interior GWB (Gypsum Wall Board). You will want to confirm your new post frame building frame is stiff enough to prevent undue deflection from cracking the GWB joints.

Learn more about commercial girts here: https://www.hansenpolebuildings.com/2011/09/commercial-girts-what-are-they/.

DEAR POLE BARN GURU: I have property in an area that floods from time to time. For example, can a monitor barn (approx. 25×50). with side sheds be built. The idea I have is the side sheds serving as porches and under the barn would be a drive through area. there is already a modular home built in the area that is elevated about 4 ft. off the ground and they have had no problem . Thanks, MIKE in MOLINA

DEAR MIKE: You can build any sort of post frame building on your site which will be allowable under the limitations of your Planning Department. As to dealing with the flood issues, you should have your property elevations determined by a surveyor, and the site where the building will be constructed can then be built up so the floor will be above the flood plain level.

 

DEAR POLE BARN GURU: I recently purchased several 4’x50′ reflectix double bubble foil rolls. I’ve put up a brand new 30×56 post frame metal building and was going to use this product to keep the metal roof and walls from condensating not to mention I was hoping it would help keep some heat in during the winter and heat out during the summer until I truly insulate the inside. My question is, for ease of installation on my metal roof panels, is it acceptable to put the foil on the underside of the 2×6 roof joists instead of sandwiching it between the roof joists and metal? There will be no roof venting due to leaving the trusses and attic space exposed. My only real concern is that it could condensate worse installing it this way. Also I will not be continually heating the building. Only on occasion with a propane heater while I’m working. I’m not real savvy when it comes to insulation and condensation control so any advice would be appreciated. Thanks in advance! Brandon

DEAR BRANDON: While it would be easy to install the steel roofing without having to place the reflective radiant barrier between the roof purlins and the roof steel, it is going to be the easiest method to limit condensation issues, given the product you have invested in. Hopefully you have gotten the double bubble with a tab along one side and an adhesive pull strip, otherwise you will have to tape all of the seams as you work your way along the roof.

Could you place it on the underside of the purlins? Yes, however in order to work as an effective condensation control, it has to be absolutely tightly sealed against any protruding framing members. Remember the time you saved on installing the roof steel? You just ate it all up.

If you have not yet ordered your steel roofing you could resell the reflective radiant barrier online and order steel with I.C.C. (Integral Condensation Control) attached (see the article and video here: https://www.hansenpolebuildings.com/2017/03/integral-condensation-control/).

 

 

How Can I Reduce Humidity?

Welcome to Ask the Pole Barn Guru – where you can ask questions about building topics, with answers posted on Mondays.  With many questions to answer, please be patient to watch for yours to come up on a future Monday segment.  If you want a quick answer, please be sure to answer with a “reply-able” email address.

Email all questions to: PoleBarnGuru@HansenPoleBuildings.com

DEAR POLE BARN GURU: Mr. Guru I was wondering if I could ask you a question about pole barns, because I have an issue with mine that is stressing me out. I live in Virginia and My pole barn/ 3 car garage was built in 2004 it is 28′ wide x 44′ long x 10′ tall, foil insulation roof and sides, 4″ concrete floor, gutters and downspouts, 3 insulated garage doors with 5 windows in each and an entry door. I have never noticed any moisture on my garage floor or anywhere inside in all these years, I have 2 classic cars and a 2005 truck that has never seen rain and only has 2,000 miles on it. When I went to change the oil I noticed pulleys under the hood are starting to rust along with bolts and suspension parts underneath. Could humidity be making it rust? I have a gauge in the garage that said 65 % humidity when the temperature was 85 inside. What would be my best bet to reduce the humidity?. Parking on plastic sheeting and a dehumidifier?. I also saw online where ridge vents and vented soffits help circulate air. Thanks for any reply. VAPORIZED IN VIRGINIA

DEAR VAPORIZED: While humidity does not cause rust directly, it does promote it. Rust formation will depend upon the carbon content of the steel, as well as the amount of oxygen in contact with the steel.

From my research, it appears 40% or lower humidity is optimal. In order to reduce humidity, the building needs to be sealed up fairly tight. If there is not a vapor barrier under the concrete floor, a high quality sealant should be put on it. A Tyvek or similar building wrap should be installed between the wall girts and siding. On the inside of wall insulation, a vapor barrier should be installed, taking care to highly seal all joints and corners.

Do not place a vapor barrier at ceiling level, as warm moist air will naturally rise through the ceiling drywall and into the attic space, which must be adequately ventilated (best method is enclosed vented soffits and a ridge vent).

Once these things are done, you may have to use a dehumidifier, but at least you have a space created which can be dehumidified.

A couple of products you may want to investigate to help remove or inhibit rust are Break Free CLP and Eezox.

Mike the Pole Barn Guru

 

DEAR POLE BARN GURU: Sort of a pole barn question, but actually a metal roof slope design question. I think your pole barn experience is more than enough to help me with this one.

I want to add a simple metal roof over my back deck.

The deck is 40′ long and projects 10′ out from the house.

Unfortunately, the slope has to be 1.5/12 for me to have 72″ height (bottom of joists) over the deck at the lowest end of the roof.

Can I meet adequate design using 2X6x10′ joists on 4′ centers with 2X4 purlins 24” OC using 28 gauge corrugated metal?

If not, should I use 3′ centers for joists or would you recommend 2′ centers?

Or is a 1.5/12 pitch not feasible in this application? I could go 2/12 pitch but the height at the lowest end of the roof trusses would only be 68″ above the deck level (a little too low for my taste).

Thanks Pole Barn Guru for any help you can give me. KAN I IN KENTUCKY

DEAR KAN I: Lots of issues going on here.

While light gauge steel roofing is a great product, it does have some limitations. If you are considering pre-painted (colored) steel, you should be aware of the warranty being void on slopes of less than 3/12.

You also should have a height of no less than 6’8” from top of decking to bottom of any framing which people could walk under (and 7’ would be better yet).

As to sizing of rafters (joists as you have called them), you can use Table R-13 at: https://www.awc.org/pdf/STJR_2012.pdf to determine adequate size and spacing based upon the live (snow) load at your particular site. You will need to know the Fb value of the material you propose to use for rafters. With Southern Yellow Pine (most common in your area) 2×6 #2 has a value of 1000 psi, 2×8 is 925 psi.

In either case, the 2×4 purlins at 24 inches on center will prove to be adequate.

You can read more about the Code requirements for patio covers here: https://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_apph_sec001.htm

Mike the Pole Barn Guru

 

DEAR POLE BARN GURU: I noticed that my light colored pole barn siding was getting a black coating (kind of looks like coal dust but it isn’t). I figured just some scrubbing with household detergent would remove it but I was wrong. It appears to have stained the paint.

Worried now that the staining is permanent. Barn is only about 10 years old. Any suggestions would be appreciated.

Thanks. STRAINING WITH STAINS

DEAR STRAINING: It really should not be stained. The following is our typical instruction, as recommended by the steel roll forming companies:

For homeowners accustomed to sanding and painting exterior walls (or paying to have done), the easy-care pre-painted steel roofing and siding convenience can lull one into complacency. But, like any outdoor material, steel siding and roofing does get dirty – dirty enough, in fact, to be cleaned at least once a year.

Dirt pickup may cause apparent paint discoloration when exposed, in some dirt-laden atmospheres, for long time periods. Slight chalking may cause some change in appearance in strong sunlight areas. A good cleaning will generally restore the building appearance and render repainting unnecessary. An occasional light cleaning will help maintain good appearance.

To maintain original building panel finish, the only regular maintenance necessary is an annual washing. Remove airborne dirt and weather-related streaks with a garden hose or pressure washer and a bucket of sudsy water. If rinsed frequently, a garden hose may be all which will be needed to use.

Light panels may be washed with either mild detergent-type cleaners or by steam and high pressure spray systems. Apply cleaners with sponge or soft brush and rinse thoroughly in cold water to eliminate cleaning agent film build-up. Follow cleaning agent manufacturer’s instructions. Test small area before applying over entire surface. Hard water deposits may be removed with a 10% acetic acid solution in cold water. Rinse thoroughly.

Mike the Pole Barn Guru

Roof leaks: Where does condensation come from?

Roof Leaks: Where does condensation come from?

When the weather turns cool in the fall, we get calls from customers with “roof leaks”, even when it has not been raining. These “leaks” are actually from condensation and are often reported as, “My steel roof is sweating”.

Steel roofing does not sweat. Having no sweat glands, it cannot produce moisture on its own. Condensation is a result of warm, moist air coming in contact with anything below the temperature of the dew point.

A classic example – ice cold beer on a warm day, moisture forms on the outside of the glass. The beer glass is not sweating and probably not leaking. It is just colder than the dew point causing moisture from the warm air to condense on the outside of the glass. Glass cannot absorb moisture, causing water droplets to trickle down the sides of the glass, creating a puddle or ring around the base.

Like glass, steel does not absorb moisture. Condensation, forming on the underside, falls off and drips on everything below. As steel is a heat conductor, it gets to the same temperature as the outside air very quickly.

Where does this moisture come from? Even in naturally low humidity climates, some degree of moisture is always in the air. You, as well as any animals housed in your building, produce a tremendous amount of water vapor, merely by exhaling. However, most of the moisture is coming from the ground beneath your building.

Do you believe concrete is a solid? Concrete actually acts far more like a sponge, soaking up moisture from below and allowing it to pass through into your building.  Check out a concrete floor when frost is coming out of the ground and the air is warmer above.

Try this experiment either on a humid day this summer, or on a cool day this fall – lay a piece of cardboard on the concrete floor in your building overnight. The next morning lift the cardboard, the underside will be damp from moisture passing through the concrete slab!

Reflective Insulation

Reflective radiant barrier will prevent most condensation

OK, so what do you do about condensation issues in a building?  If the roof has steel siding, this is actually pretty easy.  We put a condensation barrier under the steel, such as reflective radiant barrier. This has white vinyl on one side and aluminum facing on the other, to reflect heat from the sun, with a layer of air cells sandwiched in between.  It’s actually the air cells doing all the “no condensation” work by creating a thermal “break”.  Bonus points are having deflection of heat with the silver surface, making the building cooler.  And yes, this reflective radiant barrier does have a very minimal “R” value.

Back to the water issues.  Putting just plastic sheeting or house wrap on your building won’t do the trick against condensation.  You need a thermal break between the warm air and the steel.  And down the line in another blog, I’ll discuss building ventilation to decrease condensation as well.  For now, just keep in mind roof “leaks” don’t have to happen.

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