Minimum thickness of spray foam I should consider?

[OldSchool500]

I'm building a large pole building, most likely 60x120, on a very tight budget. The finished building will be nothing but a thin sheet metal that will sweat and let noise in and out. I want to cover the interior with the thinnest possible layer( 1"?) of foam, so I can do the whole building. I'm mostly interested in it's ability to seal everything up, more than insulation value. This also makes the steel panels stiffin up and not so entirely flexible.
With that said do you think it would be stupid to have such a thin layer of spray foam? Should I really bite the bullet and get 3-4" while they're at it?
I am in North Carolina, the temperature outdoors is not often very extreme - it's the humidity I have to keep out. It's currently 70 degrees outside and 100% humidity.
I'm not going to air condition the entire building, but I will dehumidify and have some smaller rooms that will be climate controlled. (and they will likely get more rockwool insualtion)

Please don't say anything about foam "popping loose" and causing rust, this is not how spray foam works, even though many who have never seen it happen say it happens like 100% of the time. Stop saying that. The foam sticks like **** on a blanket, it has to be mechanically removed.

 

[jack stand]

I'm not sure that they'd even quote you an inch as it appears that even 2" is hard to apply that thin.
Check with them, I could be all wrong. A "flash & batt" system that was a thin 2" +/- layer of foam and traditional fg batts in the rest of the void was popular a while ago in residential construction as a cost savings. But I think there was some kind of issue. (condensation?)
This was before the adaptation of the mineral wool types and also in conditioned space that makes a big difference.
"Barn" metal really leaks a lot of air and there's conditions where it's going to leak water as there no way to counter flash the bottom of windows without a bunch of additional external trim including a flashing. (turning the water collected by the side and top j channels back on to the face of the siding)
I'd certainly consider your plan for tightening up the metal and air sealing.

 

[mike93lx]

Closed cell needs 1.5" to be an effective vapor barrier, so I wouldn't look for less than 2".

The incremental cost to go to 3 or 4 is probably less than you think since they are already there and setup.

 

[rjacobs]

Ive got 2" closed cell on my building in Texas... its plenty with my mini split... I cant imagine needing more than that and my spray foam guy said "after 2" its diminishing returns, but ill spray what you want"...

 

[OldSchool500]

I'd certainly consider your plan for tightening up the metal and air sealing.

That is mostly what the foam is for - any gaps, pave 'em over! Sounds like 2" may be more appropriate.

What do you think about sealing the metal sheets together with a big healthy bead of silicone where they overlap as they are installed? I read about this somewhere but I haven't actually herd of somebody doing this.

I will be, without question, watching as they put it together - and will fill ANY major gaps I find along the way with silicone or spray foam in a can!

 

[Old tool guy]

I will be, without question, watching as they put it together - and will fill ANY major gaps I find along the way with silicone or spray foam in a can!

Hope you don’t get in their way.

 

[JohnX14]

Go as thin as they will apply/ warranty. You need something, but not much.

 

[JohnX14]

Spray the 2" if they will stand behind the job. The vapor characteristics and R-Value don't seem ultra important in this build

 

[jack stand]

That is mostly what the foam is for - any gaps, pave 'em over! Sounds like 2" may be more appropriate.

What do you think about sealing the metal sheets together with a big healthy bead of silicone where they overlap as they are installed? I read about this somewhere but I haven't actually herd of somebody doing this.

I will be, without question, watching as they put it together - and will fill ANY major gaps I find along the way with silicone or spray foam in a can!

In my opinion, the worst leakage is air and it's much more than I would have ever thought.
A friend built a "barndo" and he showed me the airflow around every electrical box/cover plate. He did the metal himself and he's a perfectionist.
This is why I recommend making the minimal expense for tyvek or any of the non woven (like a cheap tarp) type for even a machinery shed.
9' rolls go on fast with little labor and it's well worth the $300-400.
I'd pass worrying about silicon sealing, the foam should be enough and (I don't know) but there might be a weird reaction between the 2 chemicals.
Worth investigating before you proceed anywhy.

 

[Dumber than lumber]

I'm building a large pole building, most likely 60x120, on a very tight budget. The finished building will be nothing but a thin sheet metal that will sweat and let noise in and out. I want to cover the interior with the thinnest possible layer( 1"?) of foam, so I can do the whole building. I'm mostly interested in it's ability to seal everything up, more than insulation value. This also makes the steel panels stiffin up and not so entirely flexible.
With that said do you think it would be stupid to have such a thin layer of spray foam? Should I really bite the bullet and get 3-4" while they're at it?
I am in North Carolina, the temperature outdoors is not often very extreme - it's the humidity I have to keep out. It's currently 70 degrees outside and 100% humidity.
I'm not going to air condition the entire building, but I will dehumidify and have some smaller rooms that will be climate controlled. (and they will likely get more rockwool insualtion)

Please don't say anything about foam "popping loose" and causing rust, this is not how spray foam works, even though many who have never seen it happen say it happens like 100% of the time. Stop saying that. The foam sticks like **** on a blanket, it has to be mechanically removed.

Please excuse me if I sound a little critical, but you come here asking for advice, and then you tell people what to NOT say. And with a limited history on the forum?
Anyway, could you look at sealing all the joints and seams with some kind of super-sticky tape or similar product before doing the foam? Also, to stiffen up the building could you put in more cross-bracing?
Sounds like you have plans to spend serious $$ on the entire thing. I am not convinced that spray foam by itself is a good solution.

 

[OldSchool500]

Please excuse me if I sound a little critical, but you come here asking for advice, and then you tell people what to NOT say. And with a limited history on the forum?

My history on this forum could not possibly be relevant. This is not the world authority and only source of information on shop buildings. There has already been a different thread where people try to claim foam pops off metal. There is ZERO information to confirm that, and I can't find a single person that it ever happened to. I looked. If you google it you will only find links to literally this forum from confused people who have never done it. It is sprayed directly on metal in real life ALL THE TIME. If somebody can provide a pic of that happening I would love to see it. Just because I asked a question does not mean I am stupid.

The building does not need any additional bracing. It can stand without the siding. The metal siding and roof are only slightly more thick than aluminum foil. Spraying them with closed cell foam will add rigidity, not to mention keeping outside sounds out and inside sounds in. The "building" is not flimsy. The wall panels are thin.

And "use tape"? LOL! This is a 7,200 sq ft building, not counting upper floors. I have a feeling many of you are upset because I will have a bigger shop than you ever will, by 3 or 4 times.

 

[OldSchool500]

Make sure you highlight when you think they aren't doing their job well and how they can do better.

Do you not have anything better to do than making stupid unhelpful comments?

 

[OldSchool500]

Hope you don’t get in their way.

Considering I am the boss and the owner, I'll stand in any way I want to.

I don't know why you are getting your ******* bunched up, I didn't remotely say I was doing anything to the contractors.

 

[OldSchool500]

In my opinion, the worst leakage is air and it's much more than I would have ever thought.
A friend built a "barndo" and he showed me the airflow around every electrical box/cover plate. He did the metal himself and he's a perfectionist.
This is why I recommend making the minimal expense for tyvek or any of the non woven (like a cheap tarp) type for even a machinery shed.
9' rolls go on fast with little labor and it's well worth the $300-400.
I'd pass worrying about silicon sealing, the foam should be enough and (I don't know) but there might be a weird reaction between the 2 chemicals.
Worth investigating before you proceed anywhy.

I'm not sure where you are putting that tyvek, but I can't spray foam directly onto that. WAY better up against the steel. I'm not quite sure what you are saying?

 

[jblnut]

The building does not need any additional bracing. It can stand without the siding. The metal siding and roof are only slightly more thick than aluminum foil. Spraying them with closed cell foam will add rigidity, not to mention keeping outside sounds out and inside sounds in. The "building" is not flimsy. The wall panels are thin.

Those thin little wall sheets add way more rigidity than you give them credit for.

And "use tape"? LOL! This is a 7,200 sq ft building, not counting upper floors. I have a feeling many of you are upset because I will have a bigger shop than you ever will, by 3 or 4 times.

It’s not a contest. I have 2.1 acres dried in under roof on my property with just shy of half of it being insulated and heated/conditioned year round. Don’t see me swinging around yelling about it in bold type. A big project to you isn’t a big project to everyone.


We don’t size shame here of any kind. Big shed, small shed or monster shed (7200 isn’t a monster) we don’t care. Most members are here to help and the comments you’re getting that you don’t like are because you’re asking questions and refuting all advise given.

I'm not sure where you are putting that tyvek, but I can't spray foam directly onto that.

Yes you absolutely can.

WAY better up against the steel. I'm not quite sure what you are saying?

I have spray foam on tyvek in two buildings and it’s doing fine from what I can tell. One has 2ish inches and the other has 4”. The thinner one is a building exactly like what you’re describing. I wrapped it when I built it and sprayed it a few years later. Both buildings were sprayed with an ultra thin layer of closed cell and then the rest once the first layer cured. I didn’t want to risk pushing the tin out when the full thickness cured. Looking at the outside of the buildings you’d never know there was foaming inside them.

Best reason to wrap and then spray is to be able to change out a damaged panel if needed. No good way to do that with foam directly on it.

 

[OldSchool500]

Those thin little wall sheets add way more rigidity than you give them credit for.


It’s not a contest. I have 2.1 acres dried in under roof on my property with just shy of half of it being insulated and heated/conditioned year round. Don’t see me swinging around yelling about it in bold type. A big project to you isn’t a big project to everyone.


We don’t size shame here of any kind. Big shed, small shed or monster shed (7200 isn’t a monster) we don’t care. Most members are here to help and the comments you’re getting that you don’t like are because you’re asking questions and refuting all advise given.



Yes you absolutely can.


I have spray foam on tyvek in two buildings and it’s doing fine from what I can tell. One has 2ish inches and the other has 4”. The thinner one is a building exactly like what you’re describing. I wrapped it when I built it and sprayed it a few years later. Both buildings were sprayed with an ultra thin layer of closed cell and then the rest once the first layer cured. I didn’t want to risk pushing the tin out when the full thickness cured. Looking at the outside of the buildings you’d never know there was foaming inside them.

Best reason to wrap and then spray is to be able to change out a damaged panel if needed. No good way to do that with foam directly on it.

LOL! I am not refusing any advice aside from the stupidity of not letting foam touch metal. And no, most of these people are not attempting to help. The rigidity the metal panels causes to the building is huge, but individually they are still thin and easily pushed out of shape without foam. Also you're suggesting I get rid of the vapor barrier, which is ridiculous.

Bold type is not wrong when people say stupid/off topic things.

 

[jblnut]

LOL! I am not refusing any advice aside from the stupidity of not letting foam touch metal. And no, most of these people are not attempting to help. The rigidity the metal panels causes to the building is huge, but individually they are still thin and easily pushed out of shape without foam. Also you're suggesting I get rid of the vapor barrier, which is ridiculous.

Bold type is not wrong when people say stupid/off topic things.

Not letting the touch the metal isn’t stupid, it’s one way to do it and it works. Just need to do it properly.

Not sure where I suggested getting rid of a vapor barrier ….

 

[OldSchool500]

Not letting the touch the metal isn’t stupid, it’s one way to do it and it works. Just need to do it properly.

Not sure where I suggested getting rid of a vapor barrier ….

No, it should be attached to metal, it is much stronger that way and that is the only way it can reinforce the panels and prevent them from sweating. I never asked anybody about this. Tyvek is literally NOT a vapor barrier. These are simply facts.

 

[jblnut]

No, it should be attached to metal, it is much stronger that way and that is the only way it can reinforce the panels. I never asked anybody about this. Tyvek is literally NOT a vapor barrier.

Pretty sure I never said Tyvek was a vapor barrier. Also never commented about strength on steel vs tyvek. “Should” be put on metal isn’t the same as “has to be” attached to metal.

Do what you will. Seems like you know the best way already so not sure why you need the advice of those on GJ ?

I think you know the answers but are trying to “cheap out” or find another very diy way to do something. Putting closed cell foam directly on the tin is gonna be the simplest but most likely not the least expensive option. You’re gonna have a few nickels invested in foam on that HUGE 60x120 but when you build larger structures they cost more. No need to cheap out. Spray it and be done.

 

[OldSchool500]

Pretty sure I never said Tyvek was a vapor barrier.

So then you are telling me I don't need one. Also wrong. I'm not going to bother picking apart your post piece by piece, I actually have things to do. Just know this, everything you say about me is entirely wrong and there is absolutely no reason to be an *******. If this discussion bothers you, feel free to hit the back button.

 

[jblnut]

So then you are telling me I don't need one. Also wrong. I'm not going to bother picking apart your post piece by piece, I actually have things to do. Just know this, everything you say about me is entirely wrong and there is absolutely no reason to be an *******. If this discussion bothers you, feel free to hit the back button.

I agree. You clearly have better things to do than reply to assholes like me lol.

I never said you shouldn’t put in a vapor barrier. Pick things apart all you want lol. For what you’re doing a vapor barrier is needed. Putting tyvex on and then spray foaming it will provide a vapor barrier just like spraying directly on the exterior steel. Half dozen one way, six another.

No need to be so aggressive and call people assholes. It’s not a good way to get decent responses to your questions. Have a good time with your building and good luck with your life

 

[OldSchool500]

I agree. You clearly have better things to do than reply to assholes like me lol.

I never said you shouldn’t put in a vapor barrier. Pick things apart all you want lol. For what you’re doing a vapor barrier is needed. Putting tyvex on and then spray foaming it will provide a vapor barrier just like spraying directly on the exterior steel. Half dozen one way, six another.

No need to be so aggressive and call people assholes. It’s not a good way to get decent responses to your questions. Have a good time with your building and good luck with your life

No need to argue about irrelevant things or what my knowledge is. The foam is the vapor barrier. I said that in the beginning. How many times do I have to say that? If you put any kind of sheeting underneath to stop it from adhering to the metal is only going to let more moisture in! It will also not strengthen anything. You cannot make a better seal than spray foam on steel!

 

[bob smith1]

Just wow, I was confused when this dude responded to another thread. Now I can see the coo-coo. As you were sir. Might be the sort of building we investigate for insurance when it falls down. "But that foam is so strong"....lol

 

[OldSchool500]

Just wow, I was confused when this dude responded to another thread. Now I can see the coo-coo. As you were sir. Might be the sort of building we investigate for insurance when it falls down. "But that foam is so strong"....lol

The problem is you are too stupid to understand what it is that I am doing. At least half of you here are very, very stupid and worthless people.

 

[The Cobbler]

Thread closed . no need for foul language as used.
This is a civil discussion forum. keep it that way .
one user has gone to ban camp