Recommendations/experiences with spray foam for existing shop

[ultrarunner]

With the plastic sheet panel separation one benefit is lost and that’s glueing the members together here in earthquake country… at least this a pitch I’ve heard.

 

[paulsharvey]

The biggest thing with rigid foam, depending on how the metal shop is framed.

Is it a red iron PEMB,.a fairly typical tube type frame, and if so, is it vertical-vertical; horizontal-horizontal; or vertical roof and horizontal walls? Is it a quonset hut style?

So, with red iron, you would have a (pretty) consistent spacing purlon to purlon , but they do sag, so still, going to be some rips, and then spray can filled gaps.

But the biggest problems is holding the foam. You can't screw it through the metal panels. Maybe you could screw it to a hat channel, or similar, or use liquid nails to glue it directly to the inside of the panels; but you still have those gaps, coorigations, ect

 

[WinterDeere]

Sounds like a huge time suck for a solution that's ultimately a kludge. I'd just drop the coin and get it spray-foamed by a pro. I don't regret having mine done, my heating and cooling costs on that 1200 sq.ft. are so small that we didn't even notice any change in our overall home energy costs after installing HVAC in the shop. I doubt I'd be able to claim that with any of these other jury-rigged solutions.

 

[EscapedSuburbia]

I don't know if this is helpful, but for a 40x60 pole barn I got a quote for $24,679 for 2" foam on walls and 4" under roof. Fiberglass (R19) in walls and R38 blown in ceiling would be $9550. I'm going with foam. I want the rigidity, vapor barrier, and gap/hole filling that foam gives. This is my forever dream shop so I'm going to do it right.

 

[jjeff]

There's only a few things I won't attempt to diy myself spray foaming large square footage is one of them when I got my cabin spray foamed open cell on 2x6 walls and closed cell on room in attic truss cavities. Cabins 24 wide x 30 long cost 6k over ten years ago by a local company up there was one of the most expensive things I hired out on my cabin. I couldn't have been happier with end result there was never any noticable no off gassing. Open cell should be less expensive than closed cell however it has less r value. I keep the place heated all winter at 40 degrees with electric baseboards. .25 a kwh I usually pay more for the mandatory 35 Dollar line maintenance fee than actual power to keep the place heated when I'm not up there in the winter. Anything in the future I'll build for living in will have spray foam.

 

[EddieWalker]

I've worked for a few clients that have spray foamed their shops and their houses. From what I've seen, 2 inches of closed cell gives good results. Even with the shop doors wide open in the heat of the day, it was significantly cooler inside the shop then outside. No AC in the shop, just the insulation.

In another metal shop, my client went with open cell. The cost was a lot less and it was over a foot thick. The results felt good too. He had a couple of window AC units in there and even though the roll up door wasn't insulated, it was nice and cool in there. He didn't believe me when I told him that open cell has a reputation of rusting out the metal, but a couple years later I ran into him at Lowes and he was trying to find something to deal with the rust on the metal that had just started to show up.

I've worked on and been in a few houses with open cell sprayed to the roof and the results have been catastrophic. One was only two years old and the shingles where curling with a lot of rock missing. It really looked like a 40 year old roof that was at the end of its life. It was for sale for $850,000 and nobody bought it. The last I heard, it's still for sale almost five years later with a much lower price, but not enough to deal with the foam issue.

The house I'm working on right now has open cell foam on its roof. It was done about 5 or 6 years ago by the previous owner. The shingles still look good on it, but the gable ends are rotting away. They used MDF siding above the brick and it's all deteriorating really bad. MDF is alright f it's kept dry and painted. Since the underside was never sealed, the moisture in the open cell foam put moisture right on the MDF siding. I'm not messing with that repair, it's massive and extremely difficult to get to with the peak being 30 feet up. The bids to replace it are ranging from $55,000 to $93,000

When I added on a 3 car garage to my house, I had a valley that didn't give me very much room for insulation. Here in Texas, R60 is the best you can get for keeping your attic area cool. That's about 2 feet of blown in insulation. I had 7 inches in that area so I went with the spray foam kit listed above. Kraken spray cans. I found that the first half of the can went on pretty good. It's unbelievably messy with the spray going way off to the sides of where you are spraying. What did go on the metal was pretty good, but then once the can was about half empty, it sputtered and instead of spraying several inches wide, it liked to spray more like Great Stuff, but not as fluffy. It also didn't stick as well and a lot more of it fell to the ground. Overall, I was able to get it all done with several more cans of Great Stuff to fill the areas that needed it, but I'm not going to do that again.

I think the best way to do a barn if money isn't an object is to spray 2 inches of closed cell, then get your R value from fiberglass. Air penetration is the biggest battle and what defeats AC more then anything else. Once you get the building sealed in by blocking the air, it's pretty easy to retain your temps with fiberglass.

The walls are easy, but the ceiling can be a challenge. Since heat rises and cold falls, the ceiling is where 90% of your heating and cooling issues happen. Walls are mostly to stop the air from getting in, which is why R13 or R19 works. Windows and doors are less then R5, but if sealed from the wind, it's not an issue. The attic needs to have the highest R value possible to get the best results!!!!

When I build my shop, I'm going to have a metal roof and wood trusses. I'm going to have a metal ceiling and spray 2 feet of Attic Cat loose insulation up there for an R60 rating. The metal roof will have a full ridge vent. To me, this is the best way to deal with the heat in Texas for the money. Walls will be fiberglass bats, and my exterior sheeting will be taped to keep out he wind. I do not plan on using foam except for filling gaps where Great Stuff can do a better job.

 

[Snobdds]

I've worked for a few clients that have spray foamed their shops and their houses. From what I've seen, 2 inches of closed cell gives good results. Even with the shop doors wide open in the heat of the day, it was significantly cooler inside the shop then outside. No AC in the shop, just the insulation.

In another metal shop, my client went with open cell. The cost was a lot less and it was over a foot thick. The results felt good too. He had a couple of window AC units in there and even though the roll up door wasn't insulated, it was nice and cool in there. He didn't believe me when I told him that open cell has a reputation of rusting out the metal, but a couple years later I ran into him at Lowes and he was trying to find something to deal with the rust on the metal that had just started to show up.

I've worked on and been in a few houses with open cell sprayed to the roof and the results have been catastrophic. One was only two years old and the shingles where curling with a lot of rock missing. It really looked like a 40 year old roof that was at the end of its life. It was for sale for $850,000 and nobody bought it. The last I heard, it's still for sale almost five years later with a much lower price, but not enough to deal with the foam issue.

The house I'm working on right now has open cell foam on its roof. It was done about 5 or 6 years ago by the previous owner. The shingles still look good on it, but the gable ends are rotting away. They used MDF siding above the brick and it's all deteriorating really bad. MDF is alright f it's kept dry and painted. Since the underside was never sealed, the moisture in the open cell foam put moisture right on the MDF siding. I'm not messing with that repair, it's massive and extremely difficult to get to with the peak being 30 feet up. The bids to replace it are ranging from $55,000 to $93,000

When I added on a 3 car garage to my house, I had a valley that didn't give me very much room for insulation. Here in Texas, R60 is the best you can get for keeping your attic area cool. That's about 2 feet of blown in insulation. I had 7 inches in that area so I went with the spray foam kit listed above. Kraken spray cans. I found that the first half of the can went on pretty good. It's unbelievably messy with the spray going way off to the sides of where you are spraying. What did go on the metal was pretty good, but then once the can was about half empty, it sputtered and instead of spraying several inches wide, it liked to spray more like Great Stuff, but not as fluffy. It also didn't stick as well and a lot more of it fell to the ground. Overall, I was able to get it all done with several more cans of Great Stuff to fill the areas that needed it, but I'm not going to do that again.

I think the best way to do a barn if money isn't an object is to spray 2 inches of closed cell, then get your R value from fiberglass. Air penetration is the biggest battle and what defeats AC more then anything else. Once you get the building sealed in by blocking the air, it's pretty easy to retain your temps with fiberglass.

The walls are easy, but the ceiling can be a challenge. Since heat rises and cold falls, the ceiling is where 90% of your heating and cooling issues happen. Walls are mostly to stop the air from getting in, which is why R13 or R19 works. Windows and doors are less then R5, but if sealed from the wind, it's not an issue. The attic needs to have the highest R value possible to get the best results!!!!

When I build my shop, I'm going to have a metal roof and wood trusses. I'm going to have a metal ceiling and spray 2 feet of Attic Cat loose insulation up there for an R60 rating. The metal roof will have a full ridge vent. To me, this is the best way to deal with the heat in Texas for the money. Walls will be fiberglass bats, and my exterior sheeting will be taped to keep out he wind. I do not plan on using foam except for filling gaps where Great Stuff can do a better job.

Open cell foam should be banned in my opinion. Even professionals were not using it correctly. It should be used for R value only, but only after robust vapor sealing. Open cell is hydrophobic and just keeps the moisture retained. That stuff just ends up costing more in the long run.

There were entire neighborhoods in Minnesota that had to be demolished to due closed cell foam and mold.

 

[CliffordK]

We are doing spray foam on our house under construction. There's a vapor barrier between the roof metal and the foam, and on the vertical panels and the sheathing. Had we done the shop, it would have also had a Tyvek-like vapor barrier.

Should you ever need to replace a panel, you'll want that barrier there foam fused to the panels.

In the habitable part of the shop I'll be doing standard batts in a 2x4 stud wall.

Interesting thought on the vapor barrier. In theory the closed cell itself is will prevent the movement of vapor and moisture, and can effectively seal small leaks, whether or not that is actually a good thing.

My roofing machine makes a crimped standing seam which I believe would be very difficult to remove panels unless I find different dies for it.

I'm hoping to build a structure that will be able to largely withstand an external fire. So, I really want an anoxic layer below the steel.

 

[CliffordK]

One other thing I'd research about a vapor barrier between steel roofing and closed cell foam is the possibility of trapping moisture between the vapor barrier and the steel roofing which could potentially destroy your roof... RUST.

With direct spraying of closed cell, the foam should prevent moisture from reaching the metal.

Anyway, there seems to be some debate of the dangers. Perhaps it depends on the climate. Nonetheless, it is worth researching.

 

[dstig1]

There is sound building science behind this application. First off you MUST use closed cell foam (rigid) as open cell is not a moisture barrier, which leads to the rust issue Eddie mentioned.

The points about dewpoints that Snobdds mentioned is partially correct, but the proper way to look at it is that you must maintain the "condensing surface" above the dewpoint of the air with insulation that is not moisture permeable (thus closed cell vs open). In this situation that surface is the inside face of the metal. There are ways to do this with both external and internal insulation, but you really only have the one inside option in this case. There are charts for how much closed cell foam is needed by climate zone to maintain that surface above the DP. I'll see if I can find it. Up here it needs 4" for this to work, and is what I did on my vaulted roof, then filled up with dense pack cellulose for more R value. I'm expecting you are correct on 1-2"

Foam is very flammable. There is an intumescent spray coating they can put over the top of it as someone mentioned. I have that in my utility room which is unfinished and has some exposed foam and the inspector required it. If you are not going to cover it, this is something to consider.

While you can do the board-and-seal method that was mentioned, it is a ton of work and hard to make as good as spray foam. Up to you if you want to try that or not.

Finally DO NOT DO THIS YOURSELF. The DIY foam kits are great for small jobs but are in no way comparable to the professional equipment and experienced installers. You will regret it big time if you DIY this. Now if you need some additional foam to seal up some stuff after you are done with your changes, then by all means get a kit for that. Also, like most things, the BF coverage the kit states will not end up being true and you will come up short many or most times, so plan for that. I suspect much of that has to do with experience and conditions (temp, esp)

Edit: It looks like your zones would require R8 interior closed cell foam, so about 2". The requirements are for dwellings, so you can do as you wish in a shop, but the recommendations were made for a good reason, so I'd recommend sticking with it. Here is a link, though it is not easy to interpret to the unfamiliar

The Right Foam for Your Climate

Follow the steps below to determine the proper spray foam insulation to use for your application and climate. STEP 1: Determine your Climate Region The Department of Energy's Building America program has defined several distinct climate regions in the US. Use the chart or link to identify which...

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