Insulation Installation questions.

[BobLon]

I've been lurking here for a month or so because I need to insulate my 30x35 steel shed. I am going to air condition it.

It is a pre-engineered Carolina Carport shed (not my choice but is existing with a house we just bought).

After all I read (here and other places) I had decided to do closed cell spray foam. Now there's stories of potential rust issues down the road. I really don't want to open that can of worms but the topic does beg a lot of questions.

Anyhow, no matter how I go I am going to build some stud walls inside.

I am in Florida (hot/humid) and my current thinking is to use rigid foam panels.

So, if I get foil faced rigid foam panels is ok to adhere them directly to the 2.5" columns, foil side towards the exterior. That would leave an air space between them and the exterior steel panels. Then I want to put the stud walls inbound of that.

Can I just stick them to the columns with some adhesive?

Thanks,
BobL.

 

[Shiftless]

How do you ventilate the space between the rigid foam and the steel walls?

 

[BobLon]

I plan on not going all the way to the ceiling with the walls/insulation board. The 'ceiling' of the enclosed space will be below the roof. It would vent up between the columns into the space above the 'ceiling'. Could put a small fan high up on the gable end above the enclosed interior if I need to.

 

[Shiftless]

Seems to me that would work fine without a fan.

 

[BobLon]

Sweet, that's the answer I was hoping for.
Thank you.

 

[BobLon]

So just using adhesive to attach the foam to the columns is ok too?

 

[bigmobrown]

All of the spray foam installers here in central Texas recommended open cell foam for my 30x40 Carolina Carport build out. I added 2x4 framing on the inside walls with an 1/2 inch gap between the steel beams and the wood framing for a thermal break. It's amazing how air tight and super insulated this building is now.

 

[bigmobrown]

Here's a photo of my 30x40 Carolina Carport build out with open cell spray foam insulation.

 

[BobLon]

Did they say why they recommended the open cell over the closed cell there?
What did you put behind the frame walls to contain the foam? Radiant barrier?
Did you have them spray directly to the roof?

It does look cozy.

BobL.

 

[bigmobrown]

BobLon,

Open cell foam was recommended because closed cell foam forms a vapor barrier, which is not required by code and is not recommended in this area of Texas. The foam was sprayed directly on the inside of the metal sheathing and is about six inches thick on the walls and about eight inches thick on the underside of the roof. The thickness of the foam works as a radiant barrier.

I'm able to heat and cool the entire 1200 sf space with a single 18K btu mini-split heat pump A/C.

It only took the foam contractor about four hours to completely spray the whole building and shave the walls to the studs.

 

[BobLon]

Oh, ok, thanks for the clarification. I mis-interpterpreted your earlier statement about the 1/2 " gap. Being in Florida it is hot AND humid and that might change the equation.

So you don't have any concerns about the foam being in direct contact with the steel panels?

There have been some reports of potential rust issues down the road doing that but I have no clue how well founded they are. I was all set to spray foam mine but now I'm a little leary.

Thanks.