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Condensation Above Metal Building Roof Insulation

Condensation Above Metal Building Roof Insulation

Only those few long time readers or those who had time on their hands and have read every blog I ever wrote will recall this story about my adventures with metal building roof insulation: https://www.hansenpolebuildings.com/2011/11/metal-building-insulation-in-pole-buildings-part-i/.

Reader JOSH in CORVALLIS is having issues with how metal building insulation is (or in his case is not) performing in his post frame hangar. He writes:

“I am a first time builder and finished a 40×50 Hangar by myself a few years ago. It all came out perfectly with one exception. Every year when the temperatures change rapidly and the moisture is high I get condensation that fills up the roof insulation along the intersection of the roof and the top girt. 

I used fiberglass backed with vinyl laid under the metal roofing. When I installed it I rolled it out from one side of the building up over the peak and down to the other side in a continuous piece. Each piece then was overlapped to the next one, folded over and stapled down to the purlin. I feel that was done well. Where the insulation meets the top girt (purlin) I finished it off there by folding it over on itself and stapled it to the top of the top girt (purlin) so the metal roofing was laid on top of it and screwed down to that top girt (purlin) only touching the vinyl backing. 

At the peak of the roof I have a gap of a few inches between the sheet metal from one side to the other, with the ridge cap covering that gap. I used a duckbill plier tool to bend up the sheet metal along the top edge before installing the ridge cap to help keep out a driving rain but let air flow through. 

The roofing tips I had received from other DIY builders influenced the way I did things and I now question if those things are causing this condensation issue I have. The 3 main things are how I tacked the insulation to the top girt (purlin) by folding it over onto itself. The droop of the insulation between each purlin (about 2 inches droop), now I think that maybe should be taut against the metal. And the bending of the metal sheet up under the ridgecap as I see they sell matching foam insulation strips for this area which would obviously block airflow as well as water. So my question is what did I do wrong here and what can I do to correct it?”

Mike the Pole Barn Guru writes:
I lived for a decade roughly 40 miles northeast of you in South Salem so am vaguely familiar with your weather – two seasons, warm rain and cold rain. Now seriously, it was not so bad, until I moved back to Eastern Washington’s high desert and had to have webbing removal surgery from between my fingers.

I have given your scenario some serious thought since you wrote with your challenge.

My general method of problem solving begins with what is causing this situation, beginning with possible sources.

Usually I would point my finger at roof leaks, however you have narrowed this down to only when humidity is high. Most often increased humidity inside of buildings is due to no vapor barrier beneath a slab-on-grade. If this is your particular circumstance, I would recommend applying a sealant to your concrete floor.

Normally when water is collecting just uphill of an eave strut (aka eave purlin or girt) it is due to a raw insulation edge on top of the eave strut. You have eliminated this, however humidity laden air can still enter your system here unless you place inside closures between your fold over and roof steel (my guess is this is your source) https://www.hansenpolebuildings.com/2015/12/the-lowly-inside-closure/

Using Metal Building Insulation as a Condensation Control usually fails due to seams being poorly sealed. A 100% tight seal is essential for adequate performance. Here is how they should be done:

You have no airflow at your ridge, due to having run insulation continuous from eave-to-eave. I would cut away insulation between your ridge purlins and install vented closure strips under your ridge cap. This will give a point for warm moist air to exhaust from inside your building and prevent any blown rain from entering.

I hope this helps….please let me know how it all works once you apply the remedy.

 

This entry was posted in Concrete, Insulation, Pole Barn Questions, Roofing Materials, Pole Building How To Guides, Pole Barn Planning, Ventilation and tagged , , , , , , on by .

Lots of Bad Advice for Retrofitting Roof Insulation

Lots of Bad Advice for Retrofitting Roof Insulation

Reader DAVE in GALES CREEK writes:

“I’m desperate, or I wouldn’t be bugging you with this. We have a 38×48 pole barn / shop with concrete pad that was on our property when we bought it. There are 4 sections between trusses, and one of those has been walled off as a work area. I really need to insulate the ceiling / roof of this area. For heating purposes and some extra sound absorption. The roof has 2×6 rafters running parallel to the length of the building – no soffits or vents. The existing insulation is vinyl backed fiberglass between the rafters and metal roofing. It does very well for what it is, no problems. I’ve had so many people tell me EVERYTHING I learn is wrong – it’s cost us dearly over the last few years being paralyzed with fear that we might do it wrong and regret it. How would you do this? Most say to tear out the vinyl back fiberglass, fill the rafter cavities with Rock Wool (or fiberglass), an interior vapor barrier and then cover the ceiling with PVC roofing or tin. Others say to leave the fiberglass vinyl backing in place,( Which I prefer) use Rock Wool, but leave an air gap so there will be air flow into the rest of the shop to avoid condensation on the vinyl backing. Like a mini attic space to avoid creating a double vapor barrier? I would use spray foam, but without getting into it, it’s not an option. I’d have to use foam board, rock wool or FB insulation. Could you please help us? Any advice would be so greatly appreciated. We’re losing our shirts on this project taking so long. Anything would be helpful at this point. I’d be glad to send diagrams and photos if need be? Thank you very much for your time either way.”

Mike the Pole Barn Guru answers:

While I am not a fan of vinyl backed fiberglass (aka metal building insulation), provided seams are sealed and facing is not punctured, it does provide a condensation control.

If you were to tear out what you have (would be a painfully tedious project), your only option would be closed cell spray foam directly to roof steel. Why? Because, Building Codes require an inch of clear space between insulation and roof deck from eave-to-ridge. As your building’s roof purlins prevent this from happening, any sort of batt insulation in plane of roof would not be an option.

Provided your trusses are capable of carrying added weight of a ceiling, or you can support a ceiling off of 38 foot walls on each side of this bay, your best option is to blow in insulation directly above said ceiling. First choice would be granulated Rockwool (it is not affected by moisture and does not degrade with time), second would be fiberglass. If using steel panels for a ceiling, do not blow cellulose on top of it, as chemicals in it are likely to react negatively with steel.

Leave attic area above ceiling open to balance of building, so as not to create an unventilated dead air space. Otherwise, you will need to add gable vents (as an air intake) and vent the ridge.

This entry was posted in Insulation, Pole Barn Questions, Building Interior and tagged , , , , on by .

Poor Project Planning Makes for Poor Results

Poor Project Planning Makes for Poor Results.

I am feeling WESLEY in DULUTH’s pain as he describes his situation below:

“Hello! I have a question regarding insulation and condensation. The picture shows a cathedral style ceiling with 12 inches of space between the tin and bottom of framing. My plan is to use R-38 fiberglass batts spaced from the tin by one inch. The roof is vented with two foot vented soffits and vented ridge cap. I would install a 10 or 15 mil vapor barrier then ¾ poly sheet foam and drywall. Spray foam is out of my budget so not really an option for me. There is no WRB under the tin due to poor project planning. Do you see this causing condensation issues or is there a better solution? Thanks.”


Mike the Pole Barn Guru:

While you may not like my answer, I always tell it like it is.

Without a thermal break directly between roof steel and framing you will have condensation issues, there are no two ways around it. A WRB (Weather Resistant Barrier) would not have helped your situation, as it would allow moisture to pass through and be trapped between it and your roof steel – likely resulting in premature deterioration of your roofing.

You could do:

(a) Remove roof steel and install something – least expensive being a well-sealed Reflective Radiant Barrier; next up being well-sealed Metal Building Insulation (horrid stuff to work with https://www.hansenpolebuildings.com/2011/11/metal-building-insulation-in-pole-buildings-part-i/ and https://www.hansenpolebuildings.com/2011/11/metal-building-insulation/) or solid sheathing (plywood or OSB) with 30# felt (90# if slope is under 3/12) or a synthetic ice and water shield.

Any of these would solve your condensation issue, however it creates yet another problem – trying to insulate and have an inch of unobstructed air flow from eave to ridge above insulation. Not going to happen.

Or

(b) Have two inches of closed cell spray foam applied to the underside of your roof steel, then fill the balance of cavity with unfaced rockwool batts (https://www.hansenpolebuildings.com/2013/03/roxul-insulation/).

Your idea of using fiberglass batts will result in them getting wet from condensation, losing R value and becoming a home for mold and mildew. While spray foam may be out of your budget, the expense of fixing something done wrong will make it sound cheap.

This entry was posted in Insulation, Pole Barn Questions, Pole Barn Planning, Pole Barn Structure, Trusses and tagged , , , , , on by .

Not a Hansen Pole Building

From a Distance Every Pole Barn Looks About Equal

Earlier this year I shared back and forth several conversations with a potential client (who eventually did not invest in a Hansen Pole Building).

He shared with me photos of his brother’s beautiful new pole barn shop and intended to have one built by this same builder.

Although a plain rectangular box, with absolutely no frills (things I look upon as being important – like wainscot and enclosed overhangs), from a distance it appears as though it would be highly functional.

Notice, if you will, a lovely view for a distance – meaning this building site is Exposure C for wind (See here for an explanation: https://www.hansenpolebuildings.com/2022/06/wind-exposure-and-confusion-part-iii/). How does Exposure C impact (literally) a building? It must structurally resist a 20% greater force than an Exposure B (protected) site.

Now this potential client was impressed also, because his brother’s building was fully insulated. Let’s go inside and take a look….

Well, yes – it has Metal Building Insulation, a very poor investment in a very small effective R value. Please read more here: https://www.hansenpolebuildings.com/2011/11/metal-building-insulation-in-pole-buildings-part-i/ and https://www.hansenpolebuildings.com/2011/11/metal-building-insulation/.

Nice insulated overhead door in one end – although it is insulated, don’t expect much true performance from an insulated overhead door https://www.hansenpolebuildings.com/2020/07/barndominium-high-r-value-overhead-doors-part-i/ and https://www.hansenpolebuildings.com/2020/07/barndominium-high-r-value-overhead-doors-part-ii/.

There is also nothing to lead me to believe this overhead door is wind-rated. https://www.hansenpolebuildings.com/2014/12/wind-load-rated-garage-doors/

With an Exposure C site, my guess is one morning after a 60 mph (miles per hour) or so overnight wind gust, this door will be laying flat on ground outside of the building.

This building utilizes home-made dry-set brackets to mount columns to slab. Even though these brackets have no ICC-ESR Code approval (and dry set brackets, in general, have no ability to resist moment – aka bending forces), there is one significant challenge. Only every other sidewall column has a bracket!

https://www.hansenpolebuildings.com/2014/12/dry-set-column-anchors/

Somewhere, somehow, some body neglected to install any roof truss bottom chord bracing (aka rat runs). For single trusses, this would be required no more than every 10 feet. I would imagine at least the longest diagonal truss web (as well as maybe vertical at center) should be braced as well.

In this Exposure C site, externally mounted 2×6 #2 wall girts are likely to be overstressed https://www.hansenpolebuildings.com/2012/03/girts/

Both sound engineering practice and Building Codes require roof purlins on edge to be restrained from rotating at bearing points. Solid blocking between purlins going over top of trusses, or purlins joist hung between truss top chords would accomplish this.

This story has a moral similar to “Don’t look a gift horse in the mouth”. If this building was an absolutely free gift, then it was a heck of a deal (provided it is well insured), but to have paid hard earned money for a building unlikely to survive more than a few years – not such a great deal.

Here is where I reiterate my mantra – always build from fully engineered, site specific plans.

This entry was posted in Insulation, Pole Barn Design, Pole Building Comparisons, Pole Barn Planning, Pole Barn Structure and tagged , , , , , on by .

How to Fix Many Leaks on a New Steel Roof

How to Fix MANY Leaks on a New Steel Roof

Reader GUY in SHELTON is probably wishing he would have ordered a new Hansen Pole Building right now. He writes:

“Best way to fix MANY roof leaks on a guaranteed newly built pole barn with metal roof over 2-inch vinyl glass woven insulation. Purlins are on 2 feet centers with no underlayment. Thank you.”

Mike the Pole Barn Guru advises:

Sadly this makes my case for why clients should do their installations, as rarely do we ever find an instance of a D-I-Yer having roof leaks.

You need to put whomever installed your building on notice, following whatever procedure is outlined in your written contract with them. If there is no procedure outlined, send a certified letter, return receipt requested, to them, demanding prompt repair or replacement of leaking roof panels, as well as any metal building insulation underneath. Steel panels should never be installed over damp insulation, as this moisture can cause premature deterioration of panels and void steel manufacturer’s warranty. You might want to include that the repaired roof must be inspected by a representative of whomever manufactured your building’s steel panels and require them to sign off as to repair having been done adequately, so steel panel warranty is not compromised. You will want to pay careful attention to time frames, as Washington State only requires registered contractors to offer a one year warranty on materials and labor. Should you not get a prompt correction, you need to file a claim against their Contractor’s Bond (you may want to do this anyhow, as chances are you are not the only person this builder has done poor work for, and claims are paid in order filed). It may also behoove you to engage an attorney who specializes in construction law.

If a “random miss” occurs, repair is to have someone hold a wood block underneath the hole and drive a screw through the hole into the block.  This is the manufacturer’s only approved repair for a missed screw. 

Do NOT, under any circumstance, attempt to fix a missed screw hole with caulking.

Here is a short story about how I handled a similar situation, back when I was a builder: https://www.hansenpolebuildings.com/2014/09/omsi/

This entry was posted in Pole Barn Questions, About The Pole Barn Guru, Roofing Materials and tagged , , , , on by .

Insulating a Hybrid Building

Insulating a Hybrid Building

Reader COLTON in DAWSON writes:

“Insulation question? I am going with a Worldwide Steel Building. Identical to a Perka. Part of it will be shop and part will be house. It’s a steel web truss with wood purlins and girts. I’m stuck on a lot of guys say just put house wrap on the entire outside or a foil. And batt/roll in the 2’ purlin and girt spacing. And some want to use metal building insulation and roll it on top. I’m not sold on the squashing it in between the tin and possibly causing issues there. I would rather house wrap it and fill in between the purlins and girts with unfaced fiberglass then add a clear vapor barrier inside and then install tin inside the shop and drywall inside the house. Just want your honest opinion since you lived and learned. I enjoy all your helpful information. Thanks!”

My grandson Colton just turned 10 yesterday!

Thank you for your kind words.

You are now faced with what can be a perplexing challenge with a steel framework/wood girts and purlins hybrid building – how to best insulate.

For walls – siding, weather resistant barrier (aka house wrap), unfaced batts, clear poly, interior finish works fine. On your roof, house wrap allows moisture to pass through and be trapped between it and roof steel – possibly causing premature degradation of your roofing. You need a thermal break directly below roof steel. I would recommend an Integral Condensation Control (https://www.hansenpolebuildings.com/2020/09/integral-condensation-control-2/). If this is not an available option, then a Reflective Radiant Barrier with well-sealed seams will work (we have it in six foot wide rolls with a tab on one side having an adhesive pull strip). Metal Building Insulation can be an effective condensation control under roof steel (provided seams are sealed), however it is difficult to work with, provides limited actual insulation value and can cause your roof steel to pucker. Code requires ventilation from eave-to-ridge above batt insulation between purlins, and there is just no practical way to do it. Instead, place ceiling joists between bottom chords of steel frames and blow in fiberglass insulation. Vent dead attic space above insulation (ideally at eaves as an intake, ridge as an exhaust).

This entry was posted in Insulation, Pole Barn Questions, Pole Barn Design and tagged , , , , , on by .

Things You Want to See On a Building Proposal

Things You Want to See on a Building Proposal/Contract

Maybe you (as a soon to be building owner, building contractor or provider) are satisfied with being overly vague when it comes to what you are buying or selling. From a contractor/provider standpoint, this gives you lots of leeway to add ‘extra dealer margin’ by providing minimal (or less than minimal) components to unsuspecting buyers.

Now, my employer happens to offer a “price match guarantee” for any comparable building package. If I had a dollar for every quote from a competitor where it was impossible to even determine what was being proposed to be provided, I would be sitting in a beach chair along an ocean, not writing this article!

Today I am going to address a few highlights, if you are pondering a building investment, you will want to pay close attention…provided getting best investment for your money is important.

Things like building dimensions (width, length, eave height and roof slope) as well as roof style (gable, single slope, monitor, gambrel, dual slope, etc.) might seem to be no brainers, however I find even some of these certainly important features to be overlooked!

While there does exist an actual ANSI (American National Standards Institute) definition of Eave Height – most builders and vendors are unawares or just plain choose not to use it. Somewhere your agreement should spell out what is proposed or provided so all have a clear understanding. (Please read more here: https://www.hansenpolebuildings.com/2012/03/eave_height/)

Will this building be fully enclosed, partially enclosed or merely a roof? It makes a difference in wind design, so should be clearly delineated.

FEATURES

This is not meant to be a comprehensive list, but is to provide an idea as to how extensive it should be.

Thickness (gauge) of steel roofing and siding, as well as warranty AND substrate should be called out. Caution here as IRC (International Residential Code) Table R905.10.3(2) requires a minimum of AZ 50 for 55% aluminum-zinc-alloy-coated steel (Galvalume) or G-90 for Galvanized steel. These same requirements can be found in IBC (International Building Code) Table 1507.4.3(2). Lesser coatings can only be used for “U” buildings. Will there be wainscot, and if so will there be trim between it and upper wall panels?

How will roof steel condensation be controlled? Not addressing this now will cause challenges later. Integrated Condensation Control (Dripstop or Condenstop), Reflective Radiant Barrier (aka Bubble – and it is NOT insulation), Metal Building Insulation (vinyl faced fiberglass), Sheathing (OSB or plywood) with 30# or heavier felt or a synthetic ice and water shield? Tyvek or other similar housewraps (Weather Resistant Barriers) are not effective for condensation control.

How will any dead attic spaces be ventilated? Soffits, gable, ridge?

If other materials are to be used for roofing and/or siding, specifics as to thickness, quality and warranty should be clearly delineated.

Overhangs – open (no soffit) or enclosed (with soffit). Length of overhangs. Soffit material to be used (vinyl, steel, aluminum) as well as vented or non-vented.

Any overhead sectional or roll-up (coil) doors should be appropriately wind rated. Residential or commercial doors? Smooth faced, long panel or short panel? And glass, and if so, inserts? Specifics as to any manufacturer’s stated R values, thickness of steel, interior backers, track options (standard, low headroom, high lift or with run of roof), color, finish painted or primed only, vinyl weather seals, steel trims on jambs,  openers and operators should be called out.

Entry door width and heights, is door wood, steel, aluminum, vinyl covered, fiberglass? Jambs wood, steel, aluminum, vinyl covered wood? Doors and jambs finish painted or primed only? Crossbucks? Raised Panel? Glass? Wind rated? R value? Keyed lockset, dead bolts?

Windows with dimensions, type of frame material (aluminum, vinyl, composite, etc.), type (sliding, single hung, double hung, fixed, casement, etc.). Glazing (single, double or triple pane, tempered or non-tempered glass). Color of frame. Integrated J channels? Screens? Gas filled? U-factor and SHGC.

Wall framing (girts) external or bookshelf? External girts rarely meet Code deflection requirements and framing will have to be added to create an insulation cavity or apply interior finishes.

Trusses designed to support a ceiling load? If for sheetrock, a 10 psf (pounds per square foot) bottom chord dead load is required.

Future Building Owners – if it is not specifically called out for, do not assume you are getting it. Building providers and contractors – if you are providing a feature and do not call it out, you are doing a poor job of selling yourself.

Our next article will delve into “Code” design requirements – don’t miss out!

This entry was posted in Steel Roofing & Siding, Trusses, Windows, Barndominium, Insulation, Pole Barn Design, Building Interior, Building Styles and Designs, Roofing Materials, Pole Building How To Guides and tagged , , , , , , , , , , , , , on by .

Decisions, Decisions – Vapor Barrier for a Post Frame Steel Reroof

Decisions, Decisions – Vapor Barrier for a Post Frame Steel Reroof

There are few reasons to replace an existing post frame building’s steel roof, as properly installed it should last a lifetime. Among these reasons could be:

Tired of Existing Color
Old roofing was nailed on
Tree fell through roof

This last one actually occurred to our shouse (shop/house) when I lived in Northeast Washington!

Loyal reader and Hansen Pole Buildings’ client MIKE in COUPEVILLE writes:

Reflective Insulation“I am currently re-siding/re-roofing an existing pole building in order to match the exterior of the building I recently purchased from you.  This building is roughly 32 x34 and the roof purlins are 2×6 on end roughly every 2 feet.  I’m using Fabral’s grand rib 3 29ga for the roof and it will have fully vented soffit overhangs and a vented ridge cap.  I am trying to figure out what I’m going to do for at least a vapor barrier under the roof steel, I see you seem to recommend foil faced bubble insulation but that is not very common in my area.  I am seeing a lot of people using lamtec wmp-vrr (fiberglass insulation with a poly backing)  3″ thick and I believe they lay these wide rolls on top of the purlins and then place the metal roofing on top of that then screw down the roofing compressing the fiberglass insulation between the metal roofing and the purlins.  Have you seen this style of insulating before?  Do you think it is an acceptable way of doing it?  I see as killing two birds with one stone.  I may be insulating this shop in the future so if I do then the roof is already insulated plus I believe it acts as a vapor barrier which is the main reason to do it as I don’t want any condensation dripping down on the inside of the shop.  I live in the Seattle area if that helps to know what my climate is like.  Thanks in advance for your input.” 


Mike the Pole Barn Guru responds:

Our recommendation would be to order your roof steel with factory applied I.C.C. (https://www.hansenpolebuildings.com/2020/09/integral-condensation-control-2/).

Metal Building Insulation (fiberglass with a vinyl facing) is a decent condensation control, provided all of the seams are tightly sealed. It is a pain to work with, provides very little effective insulation value and makes your roofing pucker outwards between purlins https://www.hansenpolebuildings.com/2011/11/metal-building-insulation-in-pole-buildings-part-i/.

If it is too late for an I.C.C. then the radiant reflective barrier (https://www.hansenpolebuildings.com/2017/05/effective-reflective-insulation/)

 is probably your best option.  Order in six foot width rolls to minimize seams and make sure to get a product including a tab along one edge with an adhesive pull strip attached.

This entry was posted in Insulation, Pole Barn Questions, Roofing Materials, Pole Barn Planning, Steel Roofing & Siding and tagged , , , , , , , on by .

How Best to Use Metal Building Insulation

How To Best Use Metal Building Insulation

Loyal reader ANDY in SOUTH CAROLINA writes:

“ I read with interest the article “What house wrap is good for” on your website and would like to include house wrap on a pole building I’m currently planning to build in the upstate of South Carolina.  Typically builders in that area simply use 3” polypropylene faced fiberglass insulation between the wall girts and steel siding. My situation is a bit different than most I have seen in that my single story building will be 1500 sq ft total, with 900ft dedicated to garage and shop space, and 600 ft dedicated to a guest apartment. If I were to place house wrap between the girts and steel as I believe you recommend, could the 3 inch faced insulation simply be placed on the inside of the girts for the garage space, and significantly more fiberglass insulation used around the apartment – inside deeper cavities of flush walls?  

Thank you.”

For those of you who need to know, here is article referenced by Andy: https://www.hansenpolebuildings.com/2012/11/house-wrap/


Surprisingly there are a lot of builders who “sell” people on how valuable a benefit Metal Building Insulation is. Long time readers may recall my personal adventures with it: https://www.hansenpolebuildings.com/2011/11/metal-building-insulation-in-pole-buildings-part-i/

Three inch thick Metal Building Insulation makes for a very poor return on investment as every time it crosses a wall girt it gets compressed pretty well to R-0. If lucky, one might net an R-3 or so out of it. It also tends to cause steel siding to pucker outward between girts. Properly sealed, it does make for a decent condensation control.

My recommendation would be to place a well-sealed WRB (Weather Resistant Barrier) between all wall framing and siding. Use commercial style bookshelf girts to create an insulation cavity https://www.hansenpolebuildings.com/2020/05/how-to-install-bookshelf-girts-for-insulation/. Use unfaced batt insulation with a minimum 6 mil clear visqueen vapor barrier on the inside. For what you would pay for three inch Metal Building Insulation, you can completely fill your insulation cavities.

This entry was posted in Steel Roofing & Siding, Shouse, Pole Building Siding, Shouse, Insulation, Pole Barn Homes, Pole Barn Questions, RV Storage, Pole Building Comparisons, Building Department, Post Frame Home, Pole Building How To Guides, Barndominium and tagged , , , , , on by .

Condensation Above Metal Building Roof Insulation

Condensation Above Metal Building Roof Insulation

Only those few long time readers or those who had time on their hands and have read every blog I ever wrote will recall this story about my adventures with metal building roof insulation: https://www.hansenpolebuildings.com/2011/11/metal-building-insulation-in-pole-buildings-part-i/.

Reader JOSH in CORVALLIS is having issues with how metal building insulation is (or in his case is not) performing in his post frame hangar. He writes:

“I am a first time builder and finished a 40×50 Hangar by myself a few years ago. It all came out perfectly with one exception. Every year when the temperatures change rapidly and the moisture is high I get condensation that fills up the roof insulation along the intersection of the roof and the top girt. 

I used fiberglass backed with vinyl laid under the metal roofing. When I installed it I rolled it out from one side of the building up over the peak and down to the other side in a continuous piece. Each piece then was overlapped to the next one, folded over and stapled down to the purlin. I feel that was done well. Where the insulation meets the top girt (purlin) I finished it off there by folding it over on itself and stapled it to the top of the top girt (purlin) so the metal roofing was laid on top of it and screwed down to that top girt (purlin) only touching the vinyl backing. 

At the peak of the roof I have a gap of a few inches between the sheet metal from one side to the other, with the ridge cap covering that gap. I used a duckbill plier tool to bend up the sheet metal along the top edge before installing the ridge cap to help keep out a driving rain but let air flow through. 

The roofing tips I had received from other DIY builders influenced the way I did things and I now question if those things are causing this condensation issue I have. The 3 main things are how I tacked the insulation to the top girt (purlin) by folding it over onto itself. The droop of the insulation between each purlin (about 2 inches droop), now I think that maybe should be taut against the metal. And the bending of the metal sheet up under the ridgecap as I see they sell matching foam insulation strips for this area which would obviously block airflow as well as water. So my question is what did I do wrong here and what can I do to correct it?”

Mike the Pole Barn Guru writes:
I lived for a decade roughly 40 miles northeast of you in South Salem so am vaguely familiar with your weather – two seasons, warm rain and cold rain. Now seriously, it was not so bad, until I moved back to Eastern Washington’s high desert and had to have webbing removal surgery from between my fingers.

I have given your scenario some serious thought since you wrote with your challenge.

My general method of problem solving begins with what is causing this situation, beginning with possible sources.

Usually I would point my finger at roof leaks, however you have narrowed this down to only when humidity is high. Most often increased humidity inside of buildings is due to no vapor barrier beneath a slab-on-grade. If this is your particular circumstance, I would recommend applying a sealant to your concrete floor.

Normally when water is collecting just uphill of an eave strut (aka eave purlin or girt) it is due to a raw insulation edge on top of the eave strut. You have eliminated this, however humidity laden air can still enter your system here unless you place inside closures between your fold over and roof steel (my guess is this is your source) https://www.hansenpolebuildings.com/2015/12/the-lowly-inside-closure/

Using Metal Building Insulation as a Condensation Control usually fails due to seams being poorly sealed. A 100% tight seal is essential for adequate performance. Here is how they should be done:

You have no airflow at your ridge, due to having run insulation continuous from eave-to-eave. I would cut away insulation between your ridge purlins and install vented closure strips under your ridge cap. This will give a point for warm moist air to exhaust from inside your building and prevent any blown rain from entering.

I hope this helps….please let me know how it all works once you apply the remedy.

 

This entry was posted in Concrete, Insulation, Pole Barn Questions, Roofing Materials, Pole Building How To Guides, Pole Barn Planning, Ventilation and tagged , , , , , , on by .

Spot Problems with This Pole Barn Photo

Spot Problems With This Pole Barn Photo

One of my Facebook friends had posted this as a timeline photo as it brought back to her fond memories of a childhood spent frolicking in hay lofts. It was so bad, I just had to save it.

So, what’s wrong with this photo anyhow?

Obviously bird excrement over everything does not pose a structural problem, but one which I would have been trying to minimize, if not avoid. One thing which was leading birds into building – excellent nesting material provided by what was once a vinyl faced fiberglass condensation control blanket (aka Metal Building Insulation).

Long ago I had espoused about joys (or lack thereof) involved in installation of Metal Building Insulation (https://www.hansenpolebuildings.com/2011/11/metal-building-insulation-in-pole-buildings-part-i/). For those of you readers who did not click upon link and read it in full, suffice it to say birds love fiberglass.

Once condensation control blanket was torn apart – there was nothing left to prevent condensation from occurring below roof steel.

Moving forward, just glancing upon structure supporting hay loft, I would suspect a high degree of under design with only chance keeping it from meeting its demise.

All sorts of things are seen hanging from trusses. Amongst these are a block and tackle, which I suspect has been used to lift bales of hay into loft. Fortunately, individual small hay bales are relatively light, as I am pretty sure trusses were not designed to support added point load weights.

While not most effective structurally, trusses can be designed to be placed upon each side of a column – provided they are done correctly. Blocking should be placed between truss bottom chords, in order to prevent weak axis bending. A bare minimum would be every ten feet.

I see no web bracing, making this highly suspect. Older barns tend to have had bracing needs neglected. Single trusses (when placed not nailed directly face-to-face into a pair, they are single) require a great deal of bracing.

Knee braces are what I see as biggest structural issue. Not only are knee braces ineffective (https://www.hansenpolebuildings.com/2012/01/post-frame-construction-knee-braces/), but when installed improperly (as in photo) they are potentially throwing a load into roof truss bottom chords trusses were not designed to withstand.

Feel free to chip in with your observations.

 

This entry was posted in Insulation, Pole Barn Design, Pole Building Comparisons, Pole Barn Structure and tagged , , , , on by .

Insulation Shows at Edge of Roof- Inside Closure Fix

The Insulation Shows at the Edge of My Roof- Inside Closure Fix 

Reader LARRY in SPRINGTOWN writes:

“We bought a Mueller building and hired their recommended installer. The roof went on yesterday. They did not use closure strips at the eaves so the insulation is visible on the outside of the building under the panel ridges where normally the closure strip would be visible. We do not have rain gutters. What is the solution besides jamming in glued pieces of closure strip at each exposed end of panel ridges?”

For those who are not from Texas and vicinity – Mueller Metal Buildings provides prefabricated all steel buildings as well as steel roofing. In looking over their website, it appears they do have a contractor assurance plan for residential steel roofing, however it would be highly unusual for them (or any company) to “recommend” an installer for complete building installation. They may have provided one or more names of installers for you to have vetted out on your own.

I will guess and say your building has metal building insulation under the roof steel (read my fascinating journey with Metal Building Insulation here: https://www.hansenpolebuildings.com/2011/11/metal-building-insulation-in-pole-buildings-part-i/).

Back in the day when this product was the condensation control of choice for roofs I experienced the same issues with installers who refused to follow instructions. The easy solution was, during installation, to run the insulation a few inches past the eave girt, peel off the insulation from the vinyl backing and fold the vinyl facing back over the eave girt. The trim at the top of the sidewalls would cover the white vinyl and all was good.

When the insulation remains exposed, the is the potential for the exposed fiberglass to wick rain water up and into your building (not fun).

So, what is the Solution?

DON’T PAY THE INSTALLER until the issue is fixed.

There are a couple of routes for the builder to follow, both of which involve removing the row of screws from the roofing into the eave girt/purlin.

Number one – do as recommended a few paragraphs ago, or number two – the insulation can be trimmed off at the outside edge of the eave girt/purlin and inside closure strips (https://www.hansenpolebuildings.com/2015/12/the-lowly-inside-closure/) can be placed to seal the space and keep the insulation dry.

This entry was posted in Roofing Materials, Insulation, Pole Barn Questions and tagged , , on by .

Loosening Roof Screws

Help! My Roof Screws are Loosening!

Ask The Pole Barn GuruOur office gets all sorts of phone calls. Besides those clients who are potential investors in new post frame buildings, there are those who have made mistakes (or had builders make them on their behalf) and are looking for fixes.

 

 

One call came in earlier this year to Hansen Pole Buildings’ Designer Rachel, who wrote:

“Guy called wondering about buying insulation from us. He was looking for fiberglass. He asked some suggestions and said he has a little issue in his roof.  He has blanket insulation and said his screws are loosening.  I told him I thought it may be the insulation was too thick and the screw was not tight to the framing.  He understands but is wondering what the suggestion may be.  Wondering if he should replace all the screws?  Told him I thought it would still be an issue but not sure.  Thoughts?”

The caller’s building has a product known as metal building insulation under his roof steel. This insulation is most typically a six foot width roll of thin fiberglass insulation usually bonded to a white vinyl vapor barrier. This insulation is installed over the roof framing with the faced side down (fuzzy side up) then the roof steel is applied on top. Installed properly, with the seams tightly sealed (which rarely occurs) and any rips taped, it does make for a fairly effective condensation control.

It also makes for a lousy insulation solution, as the fiberglass is compressed nearly to nothing as it crosses each roof purlin. I’ve heard of builders selling metal building insulation as thick as six inches and trying to convince (and often getting away with it) clients they will achieve an R-19 insulating value!

All of this fluffy insulation wants to cause the roof steel to bend upwards in between the roof purlins, in some instances beginning to look like the Sta-Puff Marshmellow Man. Between this and the compressed fiberglass at each purlin – stress is laced upon each of the roof screws. If the screws are relatively short in length and/or small in diameter, they will eventually work loose (and cause leaks).

Reflective InsulationThe best solution (although time consuming) would be to remove the roof steel and the metal building insulation, replacing it with a reflective radiant barrier and placing the steel back on the roof using larger diameter and longer screws.

If the building owner is willing to accept the look of what he has, he could attempt a fix just by changing out the screws.

The best solution truly would have been prevention – not having used metal building insulation to begin with.

This entry was posted in Pole Barn Questions, Roofing Materials, Pole Building How To Guides, Powder Coated Screws and tagged , , , on by .

Insulation Dilemma

A reader writes (spelling, grammar errors included):

“When I built my barn I had 2″ insulation bats put between the outside framing and the tin. The side toward the tin is just open insulation. The inside is that heavy with plastic or whatever it is. I built with books shelve perlins on 2′ centers. Thinking it would make it an easy job to just fill those cavities with insulation. 

Where I’m confused is on the vapor barrier. We have a local business that makes insulation. Actually my insulation came from them. They guy there told me to just slice open the white vapor barrier and add insulation then use plastic over the added insulation prior to finishing my walls. So I’m just looking for affirmation that this is the correct way to go. Or other ideas and opinions.

Thanks.”

From the description, I will assume the two inch insulation batts are what is known as Metal Building Insulation. This type of insulation is actually designed to reduce condensation issues in building which have steel roofing and/or siding applied directly over roof purlins or wall girts.

Metal Building Insulation is not an effective insulator, as the fiberglass insulation gets crushed down to nothing every time it crosses a framing member.

This particular building is designed with sidewall framing (girts actually, not purlins which are on a roof) placed bookshelf style to create an insulation cavity. The builder did not do his customer any favors and actually spent his customer’s money unwisely.

Moisture within the walls of a pole building can cause serious problems.  In the colder months, moisture tends to move from the inside to the outside of buildings.  As it passes through the walls, it may condense within them, causing the potential for rot and mildew.  In walls with insulation, the water may condense within the insulation decreasing its R-value.  In the worst case, moisture can actually freeze within the walls, accumulating until a thaw melts it and causes visible damage such as wall or ceiling staining!

A vapor barrier is designed to keep moisture in pole barns from getting inside exterior walls.  Batt and roll insulations usually come with a vapor barrier attached.  However, leakage can occur where the facings meet.  This is especially true if the facings are not stapled to the inside of the wall girts, but instead the insulation is just pressed into place or stapled on the inside of the girt (all too common of a practice with foil faced insulation).  For the best possible vapor barrier, supplement the facing by installing a 4mil or thicker clear plastic sheet over the inside of the entire framed wall before installing any interior finishes (like gypsum wallboard).

Never sandwich the insulation between two vapor barriers. For example, do not install insulation with the vapor barrier facing the climate controlled space and then put plastic sheeting, or some type of vapor barrier, across the outside of the framing. Since some leakage of moisture into the insulation in inevitable, it needs to be able to freely escape from the insulation to the outside world ….. not be trapped inside!

 

This entry was posted in Pole Barn Planning, Pole Barn Structure, Steel Roofing & Siding and tagged , , , on by .

Metal Building Insulation in Pole Building Part II

If you didn’t read my yesterday’s blog – you may want to prior to reading today’s, which is the “rest of the story” on metal building insulation, commonly known as “MBI”.

My first experience installing MBI was not a fun one, in any sense of the word “fun”.

What no one warned us about were safety issues during installation. We should have been advised to wear protective gloves, a dust mask and goggles when working with insulation. Insulation is made of tiny fiberglass shards, which can cause serious irritation of the skin, eyes, nose and throat if you don’t take proper precautions. Instead, we spent several days with red eyes, itching skin and hacking up our lungs!

Now fiberglass itself is not some “magic” insulator, it is the dead air trapped in the uncompressed fiberglass which is doing the work. Smash the air out, and you lose R value. As far as an insulator, every time metal building insulation crosses a framing member, it is compressed to nearly nothing and loses its insulation value. People have this mistaken illusion “thicker must be better”.  Not true. Going to thicker products generally does not really add to the overall heat transfer resistance.

In years since, I’ve had clients tell me how a competitor proposed to insulate their new pole building with R-11 (3-1/2” thick) or even R-19 (6” thick) metal building insulation! First, I would hate to even imagine what the steel would look like, after trying to mash insulation this thick down and screw the metal through the insulation to the roof purlins. It would NOT be pretty. (read yesterday’s blog to see why).  Secondly, there is no way the fiberglass is going to come anywhere close to being able to fully expand between the roof purlins. Keep in mind the “product” does indeed have an R-11 capability (in the case of 3-1/2” thickness), when it is laid out in your driveway. As soon as it gets compressed, R values start to shrink. My educated opinion is a 3-1/2” thick product, in service in a pole building, is probably offering a true R value of between 2 and 4 – just slightly above nothing.

We (Hansen Pole Buildings) now partner with several lumber yard chains, providing pole building kit packages to their clients. Two summers ago I was visiting one of the lumber yard locations in Pennsylvania, in order to provide training to their staff. I went out into their warehouse to greet the store manager. Looking up at the roof of this pole building, I saw tattered MBI hanging down from between the roof purlins and hundreds of birds pecking at the fiberglass, to carry it away for nesting! Any hole in the vinyl at all, and a bird in the building, will result in exactly the same scenario being replayed – much to the chagrin of the poor pole building owner who now has no roof insulation, no condensation control vapor barrier under the roof steel of his building, and nothing but a mess.

In my over 30 years of experience, I can truthfully say I’ve never seen Metal Building insulation look to be a perfect “clean and neat” install product under roof steel.  Moreover, far too often I’ve visited older buildings where the inside view of this product “over time was enough to convince me it was not the optimal choice for pole buildings underneath steel.  Back up a few days to read other blogs where I discuss vapor barrier and reflective radiant barriers.  And stay tuned – for more on other insulation products!

This entry was posted in Pole Barn Structure, Pole Barn Planning and tagged , , on by .

Metal Building Insulation in Pole Buildings Part I

It was a cold morning….and I was working on one of the first pole barns I had ever built. With the roof all framed up, it was time to install the roof steel, or so I thought.

In a pile, on the ground, were bags of something white, about as large as an oversized water heater. Metal Building Insulation (in the industry also known as “MBI”). This not being my first rodeo (and me being young and cocky), I went over to pick up a bag and found it not only was heavier than Hades, but it was also soft and squishy, not the easiest thing to maneuver and I was going to somehow get it up onto the roof?

MBI is a thin fiberglass blanket (as thin as an inch), glued to a white vinyl vapor barrier. The fiberglass is usually six feet in width, and the vinyl is slightly wider, so as to create a tab on each side. Under ideal circumstances, with no punctures in the vinyl facing and the seams tightly sealed, it can be a very effective vapor barrier. What it is NOT, is a very cost effective method of insulating a pole building.

Back at the building site, I’m doing my best to alligator wrestle a bag of this stuff up a ladder and onto the top of the roof purlins. Winning the battle, I slice open the bag and find out this stuff smells bad, really bad….rather reminded me of when our male cat staked out his territory when we were kids. Ugh!

Once out of the bag, it took several of us to stretch it across the roof and get it into place to be able to install the roof steel over it. Into place involved unrolling these gargantuan rolls with the itchy fiberglass side up. To properly install, the lead edge needs to have several inches of fiberglass removed, the vinyl facing is then folded over and staples are put through into the top of the eave purlin. The roll is run up over the ridge, down to the eave on the opposite side, and the “remove-fold-staple” process is then repeated.

Failure to start a roll properly leaves bare fiberglass at the edge of the building. Strangely enough, when the roof is wet, water droplets can get to the edge of the roof steel and actually cling to the underside at the edge, rather than dripping off the roof. Exposed fiberglass can cause these droplets to be wicked up into the insulation – causing moisture problems inside the building.

The first roof steel panel was then placed on top of the fiberglass and screwed on. First thing I noticed is the thickness of the fiberglass caused the steel to bow up in between each of the roof purlins, rather than laying smooth. My thought was it looked rather like Bibendum (aka the “Michelin Man”) from the tire commercials.

When it was time to lay the next roll of insulation in place, I asked what I was to do with the tabs on the edges and was quickly admonished, “don’t worry about them”….so I didn’t. Only years later did I find out the true purpose of the tabs was to keep any warm moist air, from inside the building, getting through the seam and contacting the underside of the roof steel and condensing. Without an absolutely tight seal, moisture will form and now be trapped in the insulation between the roof steel and the vinyl vapor barrier – potentially causing deterioration of the roof steel from the inside.

In order to properly seal the tabs, they are to be held together, folded over once, and then stapled with stainless steel staples along the full length of the seam. I truthfully know of a total of zero instances where this has actually been done.

I believe I had mentioned before, it was cold at that jobsite. It had also been cold when the insulation rolls were delivered and thrown off the back of the delivery truck. Below 40 degrees, the vinyl facing becomes brittle and will crack – which is exactly what had happened in this case. After we had the roof done from the outside, we had to use insulation tape to patch literally a hundred or more cracks and tears in the vinyl facing on the inside!

From an installation standpoint, nothing involving MBI could be thought of as being fun. Or, worse yet, profitable.  Come back tomorrow to hear the “rest of my story” on metal building insulation….

This entry was posted in Pole Barn Planning, Pole Barn Structure and tagged , , on by .
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