Tag Archives: condensation

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

Hail: http://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 (http://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: http://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: http://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: http://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: http://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 followin 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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