I'm struggling with an insulation decision - help me out please!

[cj8lvr]

I'm building a 2,220 sq ft Miracle Truss building in my back yard.
This is a steel truss building with wooden purlins and girts covered entirely in sheetmetal exterior.
My intention is to have it sprayed with 2" closed cell foam after I have it up.
In talking with a local metal building supplier (Summertown Metals) about some extra trim that I'll need for windows not in the plans at the time I ordered from Miracle Truss..... they (Summertown) asked if I planned to insulate it. I told them yes and they recommended a product that they carry that would go between the lumber and the exterior sheet metal. It's called "Therma Guard" and is made by Dutch Tech. It's *NOT* bubble wrap but the installation of it is essentially the same thing. It's different in that it has reflective foil on the top side (pointing towards the bottom of my sheet metal, and a tough polypropylene bottom layer. Overall about 3mm thick.
Some questions:
1) Does anybody here have any first-hand experience with this product or something very similar?
2) Do you think this will create any moisture issues anywhere in the equation?
3) What do you do if for some reason I need to put a new sheet metal roof on this building and the inside is sprayed with foam and this layer isn't in between the metal and foam?
4) Do you think it's worth the ~$1,400 or more to wrap it, roof and walls before installing my sheet metal.

I'm in Alabama so consider stupid humidity levels all the time, including winter months.
Here's my build thread on my shop:
https://www.garagejournal.com/forum/threads/cartotracks-miracle-truss-garage-36x50-fab-room.493983/

Product website:
https://www.dutchtechindustries.com/therma-guard/

Here's a pic of the product being installed from the Dutch Tech website:

 

[930dreamer]

If it's only purpose is a barrier between the spray foam and exterior metal, would house type wrap be cheaper? You would have to scrape/cut the foam off to replace a panel.

 

[cj8lvr]

If it's only purpose is a barrier between the spray foam and exterior metal, would house type wrap be cheaper? You would have to scrape/cut the foam off to replace a panel.

Good question.
I'd say that that is one big reason but with added benefit of some heat reflection between the foil and sheet metal maybe along with a water vapor, condensation barrier to keep any moisture away from my wooden purlins and girts.

 

[930dreamer]

Doesn't the spray foam do all that? I have a great interest is this as my shop needs all new exterior metal.

 

[cj8lvr]

Not exactly.
Foam doesn't reflect the heat and doesn't really create a barrier between your sheet metal and your wood if you're spraying it in. Think about it, when you're spraying, you're not getting foam in that area between the sheet metal and wood and if you have condensation form, it'll run right onto the top of the wood and create mold and rot. This is a barrier between them, is impervious to water, and allows for removal of the sheetmetal easily if you've sprayed it. Without it, I'd imagine it's a huge pain to remove the sheet metal from sprayed in foam that's stuck to the bottom of your metal AND your wood.

 

[readhead]

I used it on the last building we put up and it seems to be working well.

 

[cj8lvr]

I just called and talked with Eric at Dutch Tech, the manufacturer of Therma Guard.
It sounds to me like this is far superior to bubble wrap which is prone to sagging and isn't very effective in reflecting heat like their product is.
I have some concern about the condition of my sheet metal as it has had to sit in the weather, stacked for a few years before I can get this far along. As anyone building a building over the last three years knows, prices got stupid and we all had to slow down to be able to afford things. That's me. So, there's a decent chance I may really have to look at replacing this sheet metal down the road and don't want to deal with spray foam sticking to it. This product Therma Guard looks like the best option there is out there for me.

 

[cj8lvr]

Did you spray foam inside it?

 

[LopezBart]

I'm very much in the same boat with my metal building project; it's taken far longer than I expected to get permits approved, site cleared, etc. I'm looking at spray foam as well; the company from which I purchased the building has some interesting info on spray foam here: https://www.worldwidesteelbuildings.com/blog/spray-foam-insulation-for-metal-buildings/

 

[readhead]

Hopefully the sheeting has been covered. It is very common to have white rust invade the sheeting if it has been exposed to the weather for long periods. You may want to inspect it now instead of finding out when you go to sheet the building.

You are correct in assuming that replacing sheets that have been spray foamed can be a problem. We had to repair a building after a heavy winter and it took three guys two hours to remove one sheet and there were eight sheets. I void all warranties on my buildings if spray foam is installed. Not only is repair work difficult but damage from trapped moisture can be catastrophic. You may want to check with the building supplier and/or the supplier of the sheet metal to see if spray foam will affect any material warranties. Quite a few sheet metal suppliers will not cover material warranties if spray foam is installed.

 

[cj8lvr]

The sheet metal was covered for most of the time but the tarp material has begun to break down over the last few months. I'm worried about it and will be opening it up soon to peek. Fingers crossed! If I find issues it will **** for sure but I may be able to reuse some of it inside. Not sure, we'll cross that bridge when we get to it. (when we peek at the lower layers to inspect soon).

 

[LopezBart]

Hopefully the sheeting has been covered. It is very common to have white rust invade the sheeting if it has been exposed to the weather for long periods. You may want to inspect it now instead of finding out when you go to sheet the building.

You are correct in assuming that replacing sheets that have been spray foamed can be a problem. We had to repair a building after a heavy winter and it took three guys two hours to remove one sheet and there were eight sheets. I void all warranties on my buildings if spray foam is installed. Not only is repair work difficult but damage from trapped moisture can be catastrophic. You may want to check with the building supplier and/or the supplier of the sheet metal to see if spray foam will affect any material warranties. Quite a few sheet metal suppliers will not cover material warranties if spray foam is installed.

So how does one insulate a metal building? Several folks strongly recommended using spray foam on this website. I've not assembled my building as yes; I've got wood girts and purlins.

 

[readhead]

The industry standard for years has been fiberglass blanket insulation and there are many variations of fiberglass. A lot of tube steel buildings use rigid foam.

I have said in the past that spray foam is a great product in the right conditions. People love their spray foamed buildings and with good reason. It ticks all the boxes for air sealing and heating and cooling comfort.

Unfortunately we are seeing buildings five to ten years old with spray foam that are experiencing serious corrosion in the sheet metal and purlins and girts. Repairing these buildings is very expensive and I have a friend that also sells and erects buildings that had to demolish and replace a building because there was so much damage it cost more to fix than replace.

Please understand that a lot of buildings have passed that milestone but many have not. Why take an expensive chance on an unknown outcome.

 

[TnClimber]

I'm building a 2,220 sq ft Miracle Truss building in my back yard.
This is a steel truss building with wooden purlins and girts covered entirely in sheetmetal exterior.
My intention is to have it sprayed with 2" closed cell foam after I have it up.
In talking with a local metal building supplier (Summertown Metals) about some extra trim that I'll need for windows not in the plans at the time I ordered from Miracle Truss..... they (Summertown) asked if I planned to insulate it. I told them yes and they recommended a product that they carry that would go between the lumber and the exterior sheet metal. It's called "Therma Guard" and is made by Dutch Tech. It's *NOT* bubble wrap but the installation of it is essentially the same thing. It's different in that it has reflective foil on the top side (pointing towards the bottom of my sheet metal, and a tough polypropylene bottom layer. Overall about 3mm thick.
Some questions:
1) Does anybody here have any first-hand experience with this product or something very similar?
2) Do you think this will create any moisture issues anywhere in the equation?
3) What do you do if for some reason I need to put a new sheet metal roof on this building and the inside is sprayed with foam and this layer isn't in between the metal and foam?
4) Do you think it's worth the ~$1,400 or more to wrap it, roof and walls before installing my sheet metal.

I'm in Alabama so consider stupid humidity levels all the time, including winter months.
Here's my build thread on my shop:
https://www.garagejournal.com/forum/threads/cartotracks-miracle-truss-garage-36x50-fab-room.493983/

Product website:
https://www.dutchtechindustries.com/therma-guard/

Here's a pic of the product being installed from the Dutch Tech website:

I have purchased several items from Summertown Metals. I would trust what they tell you. I would just talk it over with them. My 2cents. Craig

 

[cj8lvr]

The industry standard for years has been fiberglass blanket insulation and there are many variations of fiberglass. A lot of tube steel buildings use rigid foam.

I have said in the past that spray foam is a great product in the right conditions. People love their spray foamed buildings and with good reason. It ticks all the boxes for air sealing and heating and cooling comfort.

Unfortunately we are seeing buildings five to ten years old with spray foam that are experiencing serious corrosion in the sheet metal and purlins and girts. Repairing these buildings is very expensive and I have a friend that also sells and erects buildings that had to demolish and replace a building because there was so much damage it cost more to fix than replace.

Please understand that a lot of buildings have passed that milestone but many have not. Why take an expensive chance on an unknown outcome.

Do you think a product like Therma Guard would prevent the issues that you're seeing with corrosion in the sheet metal if used and then sprayed with closed cell?

 

[readhead]

I doubt that it would support the foam. You should contact the insulation manufacturer and get their recommendation.

 

[racecougar]

I doubt that it would support the foam. You should contact the insulation manufacturer and get their recommendation.

You beat me to it. I concur.

So how does one insulate a metal building? Several folks strongly recommended using spray foam on this website. I've not assembled my building as yes; I've got wood girts and purlins.

Fiberglass batts in the walls and blown fiberglass in the ceiling is an option. If you have bookshelf/commerical girts, it's a snap.

 

[toyotadriver]

I built my house. The house is conventionally framed but has metal siding just like a barn or shop. So, it has girts on the outside to screw the metal to. Before we installed the metal, we covered the girts with 1 inch rigid foam sheets. The foam we used has silver reflective material outward (facing the metal), then dense EPS foam, then a layer of something that appears to be like Tyvek type material on the inside (but a bit stiffer than Tyvek). All seams were taped and then the metal screwed down using longer than normal screws. We then did damp spray cellulose on the inside but could have easily done spray foam also. If we had used spray foam, we could easily replace a piece of damaged metal without affecting anything because the rigid foam would still stay attached to the house and contain all insulation.

We absolutely love it. The extra layer of insulation helps keep the wood frame warmer and reduces thermal bridging. The house is very easy and inexpensive to heat and cool. Would definitely do it again.





Nothing in this post should be misunderstood, interpreted, misinterpreted, or construed to be of a political nature.

 

[cj8lvr]

I doubt that it would support the foam. You should contact the insulation manufacturer and get their recommendation.

What do you mean by “support the foam”?

 

[readhead]

The foam needs something solid to adhere to.

 

[cj8lvr]

The foam needs something solid to adhere to.

It’s sandwiched between lumber and the sheet metal and is rather rigid according to both the manufacturer and Summertown Metals.

 

[racecougar]

It’s sandwiched between lumber and the sheet metal and is rather rigid according to both the manufacturer and Summertown Metals.

I would still recommend doing the due diligence of contacting the foam supplier. Adhesion, delamination of the inner Tyvek-like layer, and flex are all concerns worth discussing.

 

[cj8lvr]

I would still recommend doing the due diligence of contacting the foam supplier. Adhesion, delamination of the inner Tyvek-like layer, and flex are all concerns worth discussing.

I just reached out to them. Their response “The foam isn’t supported solely by the wrap. It also grabs onto your wood supports (rafters, purlins and girts) so, yes it would support it just fine.”

So, it essentially creates an inverted “bridge” from purlin to purlin. The spray foam doesn’t weight a whole lot and has its own structural integrity from side to side between purlins once it cures (rather fast).

 

[Mike65]

We have a 24'x25' 2 car shop & we had the walls & roof insulated with closed cell spray foam insulation after the electrical work was completed. Today it was 34° outside & the thermometer inside said 46°. The first pic was from when I was painting it.

 

[cj8lvr]

We have a 24'x25' 2 car shop & we had the walls & roof insulated with closed cell spray foam insulation after the electrical work was completed. Today it was 34° outside & the thermometer inside said 46°. The first pic was from when I was painting it.

That looks great! What paint did you spray it with? Remember?
It’s the one thing about spray foam that I don’t like, I think the yellow color looks dingy. Kinda looks like old desktop computer equipment how it would yellow over time.

 

[Mike65]

That looks great! What paint did you spray it with? Remember?
It’s the one thing about spray foam that I don’t like, I think the yellow color looks dingy. Kinda looks like old desktop computer equipment how it would yellow over time.

We were told by the local company that did the spray foam so it did not get degraded from direct sun to paint it, so I did. I sprayed it with IIRC Valspar interior flat white paint & I used a Wagner electric spray gun to apply it. I was originally going to cover it so the sun would not degrade the foam & the owner of the foam company said just to paint it to save some money & not have to cover it.

 

[chuckauburn]

@cj8lvr Your project looks awesome. I am glad to read through all your posts. Quite helpful. I live in Auburn, AL, and just took delivery of a miracle truss building this past December. Our projects are not too different in many ways - I had to have a very expensive retaining wall installed before I could begin pouring footings and slab. This retaining wall is most of the way up (just some backfilling near the top and a stone stair cutting though it are left. My footings were poured last week. I'm doing an elevated slab - not slab on grade like you did. My steel trusses and sheet goods are all sitting on the ground stressing me out. lol!

Have you moved forward with a decision on insulation? Like you (at the time of this post) I'm trying to do some future planning for insulation and study costs. I am weighing options and I like a radiant barrier - I used roofing foil product on a small pump shed for my well but have not finished that project. The product I used looks a lot like the one you mention above.

Single Sided Solid Vapor Barrier Foil Insulation

Our single-sided solid radiant barrier foil is a good economical option for roofing without a tear off, since you'll be keeping the original tar paper (waterproofing) underlayment layer. If you're looking for an underlayment and radiant barrier in one, use RoofingFoil™ + Underlayment All-in-One...

www.roofingfoil.com

Either of these would likely work (I didn't compare which product is less expensive yet), but my understanding is that for ANY radiant barrier to work there needs to be an air gap (recommended 1/2 - 3/4" minimum) between the metal sheeting and the radiant barrier. The ThermaGaurd product installation instructions specify this as well. (So does roofing foil, so does LP Techshield, etc). This either means going back around the building with 1x4 or other furring materials (perpendicular to girts and perlins) on the top of the foil side. So more labor cost (or time) and materials to get this correctly installed. Then you could either spray foam to the backside of this wrap or put batts or whatever. Closed cell would offer structural support, but if you're planning to enclose the bays with interior sheet good like OSB or drywall, I'm not sure but the bays might have enough airspace to create their own little mircoclimate (heat rising / cool falling inside the bay - given 2x6s - 5 1/2" minus 2" of closed cell foam leave 3 1/2" of open space), not giving the full insulation benefit to the building's interior. If leaving the interior of the wall as exposed foam, this would not matter.

In a perfect world with lots of money, I would like to sheath the outside wall and deck the roof with Zip system OSB, use Rockwool / mineral wool in my bays and properly installed radiant barrier (with furring strips) outside the sheathing and roof decking. Not sure that is in the budget, but those are also things you can't really retro fit without significant pain. I think I might try to do most of this minus the mineral wool batts as that could be completed later. This allows me to get dried in and sheet metal on.

Let me know if you have made your decision!

 

[cj8lvr]

@cj8lvr Your project looks awesome. I am glad to read through all your posts. Quite helpful. I live in Auburn, AL, and just took delivery of a miracle truss building this past December. Our projects are not too different in many ways - I had to have a very expensive retaining wall installed before I could begin pouring footings and slab. This retaining wall is most of the way up (just some backfilling near the top and a stone stair cutting though it are left. My footings were poured last week. I'm doing an elevated slab - not slab on grade like you did. My steel trusses and sheet goods are all sitting on the ground stressing me out. lol!

Have you moved forward with a decision on insulation? Like you (at the time of this post) I'm trying to do some future planning for insulation and study costs. I am weighing options and I like a radiant barrier - I used roofing foil product on a small pump shed for my well but have not finished that project. The product I used looks a lot like the one you mention above.

Single Sided Solid Vapor Barrier Foil Insulation

Our single-sided solid radiant barrier foil is a good economical option for roofing without a tear off, since you'll be keeping the original tar paper (waterproofing) underlayment layer. If you're looking for an underlayment and radiant barrier in one, use RoofingFoil™ + Underlayment All-in-One...

www.roofingfoil.com

Either of these would likely work (I didn't compare which product is less expensive yet), but my understanding is that for ANY radiant barrier to work there needs to be an air gap (recommended 1/2 - 3/4" minimum) between the metal sheeting and the radiant barrier. The ThermaGaurd product installation instructions specify this as well. (So does roofing foil, so does LP Techshield, etc). This either means going back around the building with 1x4 or other furring materials (perpendicular to girts and perlins) on the top of the foil side. So more labor cost (or time) and materials to get this correctly installed. Then you could either spray foam to the backside of this wrap or put batts or whatever. Closed cell would offer structural support, but if you're planning to enclose the bays with interior sheet good like OSB or drywall, I'm not sure but the bays might have enough airspace to create their own little mircoclimate (heat rising / cool falling inside the bay - given 2x6s - 5 1/2" minus 2" of closed cell foam leave 3 1/2" of open space), not giving the full insulation benefit to the building's interior. If leaving the interior of the wall as exposed foam, this would not matter.

In a perfect world with lots of money, I would like to sheath the outside wall and deck the roof with Zip system OSB, use Rockwool / mineral wool in my bays and properly installed radiant barrier (with furring strips) outside the sheathing and roof decking. Not sure that is in the budget, but those are also things you can't really retro fit without significant pain. I think I might try to do most of this minus the mineral wool batts as that could be completed later. This allows me to get dried in and sheet metal on.

Let me know if you have made your decision!

My plan right now is gonna be to just proceed with Therma Guard. We'll attach it right over the purlins and then sheet metal right on top of that. To create an air gap in there like you described with furring run perpendicular to the purlins sounds great but will create a royal headache to how your sheet metal will then lay on top of that. With the ribs of the metal running up and down your roof, already perpendicular to the purlins, it'll sit flat. The spans between vertically run furring will leave you with sag in the sheet metal between furring strips. So, no air gap for me, metal right on top of the Therma Guard. Then, closed cell inside against the purlins and Therma Guard for me. That's the current plan. Before it can get sprayed I've gotta run all of my electrical and lines and attachments for mini splits as well. My final step in all of that will be determined later. Not sure if I'll paint the foam or use another covering over it. That's still TBD but I have miles to go before then.

For Therma Guard, I found the closest option for purchase for me was in Hayden, AL right off 65 at Summertown Metals. I picked up 10 rolls after Christmas coming home from visiting family and have it ready to go once I finish painting my trusses.

 

[chuckauburn]

My plan right now is gonna be to just proceed with Therma Guard. We'll attach it right over the purlins and then sheet metal right on top of that. To create an air gap in there like you described with furring run perpendicular to the purlins sounds great but will create a royal headache to how your sheet metal will then lay on top of that. With the ribs of the metal running up and down your roof, already perpendicular to the purlins, it'll sit flat. The spans between vertically run furring will leave you with sag in the sheet metal between furring strips. So, no air gap for me, metal right on top of the Therma Guard. Then, closed cell inside against the purlins and Therma Guard for me. That's the current plan. Before it can get sprayed I've gotta run all of my electrical and lines and attachments for mini splits as well. My final step in all of that will be determined later. Not sure if I'll paint the foam or use another covering over it. That's still TBD but I have miles to go before then.

For Therma Guard, I found the closest option for purchase for me was in Hayden, AL right off 65 at Summertown Metals. I picked up 10 rolls after Christmas coming home from visiting family and have it ready to go once I finish painting my trusses.

Curious if you got the Therma Guard and sheet metal put on? Any progress to report? I hear your point about sagging sheet metal. I think I'll probably go with 1/2" CDX plywood decking - my pitch is 3:12 so I'll probably put down a Ice+Water HT on the plywood, then tying to decide if Therma Guard is worth it on top of that? I'd then put the exposed fastener sheet metal hard to either the underlayment or radiant barrier (if used). I somehow think without the air gap for the ThermaGaurd, and plans to put insulation inside the bays, I don't know the Therma Guard worth the cost.

 

[bas157]

I know you bought the stuff already but it kinda looks like BlueTex might be similar. I'll know once the Thermaguard sample I just requested arrives. I'll compare it to the Bluetex sample I already got.

 

[MVWSR]

I know you bought the stuff already but it kinda looks like BlueTex might be similar. I'll know once the Thermaguard sample I just requested arrives. I'll compare it to the Bluetex sample I already got.

whats your opinion @bas157 ?

 

[bas157]

whats your opinion @bas157 ?

never got anything from Thermaguard, requested sample but nothing came.