Insulation between studs or on top? Metal building

[miscjames]

Question for the community.
I just had a metal building from Caroline carport that I am going to insulate with 2” 4’x8’ foam board with foil on both sides. It will be enclosed with a garage door and a man door.

Along the bottom i plan on putting up 4’x8’ plywood as to have a good wall for shelves etc.

So should i put the foam board between the stubs or on top of them?

I am not worried about the ~2.5 inches i lose with it being on top of the studs.

My thinking (which has known to be wrong from time to time).
On top of the stubs gives me a better thermal barrier and a lot less cuts.
In between the stubs would be less of a thermal barrier but would give me better surface to hang plywood from and thus the plywood could hold more weight due to the insulation would not between the metal stud and plywood.

So should i put the foam board between the stubs or on top of them?

Edited for clarity.

 

[hiddentacocatneddih]

I have an old shop I retrofitted with free pieces of foam insulation I got from crates. It was half sheets mostly so I put it between my "studs". It's a cheap junk Morton building so no rear studs

If I was to do it from start, I would put in under the metal on the outside

 

[Roadworthy]

If the carport has a metal roof insulation is a concern. If you do not insulate the inside of the metal from contact with air water condensing on the metal will precipitate and drip inside the carport. A carport being open birds will want to destroy the insulation.

 

[miscjames]

Carolina carport is the name of the company. It will be enclosed, garage door and main door. With the foil you want an air gab or it doesnt work, i am told.

If the carport has a metal roof insulation is a concern. If you do not insulate the inside of the metal from contact with air water condensing on the metal will precipitate and drip inside the carport. A carport being open birds will want to destroy the insulation.

 

[miscjames]

I have an old shop I retrofitted with free pieces of foam insulation I got from crates. It was half sheets mostly so I put it between my "studs". It's a cheap junk Morton building so no rear studs

If I was to do it from start, I would put in under the metal on the outside

the only insulation they company provides is will between the rafters/ studs is that bubble wrap stuff and i was not impressed with it.

Did you have any places that the insulation was between the studs and plywood ? If so how is it doing ?

 

[hiddentacocatneddih]

the only insulation they company provides is will between the rafters/ studs is that bubble wrap stuff and i was not impressed with it.

Did you have any places that the insulation was between the studs and plywood ? If so how is it doing ?

It's between.

It really just helps with the radiated heat from the metal. If I was doing a truly insulated shop I would skin with foil faced foam, then insulate the walls between the studs with bats or loose fill cellulose

 

[Williy]

By putting the insulation on the top less leakage as less cuts

willy

 

[CaptPat]

It's between.

It really just helps with the radiated heat from the metal. If I was doing a truly insulated shop I would skin with foil faced foam, then insulate the walls between the studs with bats or loose fill cellulose

This is my recommendation as well. Plus it will be easier to install services later if you decide to go that way.

 

[miscjames]

This is my recommendation as well. Plus it will be easier to install services later if you decide to go that way.

For electric i plan on running them on-top of the plywood in conduit.

 

[CloverKnollFarms]

When our barn was built, the foam insulation was basically used like sheathing, and then the metal placed over top. With all the seams taped with metallic tape

 

[Renze]

Along the bottom i plan on putting up 4’x8’
On top of the stubs gives me a better thermal barrier and a lot less cuts.
In between the stubs would be less of a thermal barrier but would give me better surface to hang plywood from and thus the plywood could hold more weight due to the insulation would not between the metal stud and plywood.

Steel structure building?

Metal exposed to both inside and outside will form a huge thermal bridge. In winter they will radiate lots of cold into the shed, and the cold side will have condensation, like a beer from a cold fridge on a hot summer day.
The effect of these thermal bridges can reduce the effectiveness of your insulation by half, bevause steel conducts heat so well.
If it was wooden beams i would bother less.

 

[mark in portugal]

I'm sure the job is done by now; but because others may search and find the thread, I'll add my experience.

I converted several old steel barges into homes, and had the same dilemma. At first, I put the insulation across the top and left air gaps.

The result was a lot of condensation; a LOT.

On subsequent jobs, I filled the cavities and then added another layer on top, 2+2" of rockwool.

This worked so much better, that I removed the interior walls of the first 2 barges (years later) and filled the cavities.

On one large vessel, I sprayed hot grease all over the naked steel before pressing the rockwool plates in. That was 20 years ago. The boat is doing well.

 

[miscjames]

Here is what i came up with.

 

[gsganzer]

If I was doing a metal building, I'd use the 3" fiberglass batt R-10 rolls (or thicker for more R) with the white reinforced vapor barrier that they make for the purpose. If the walls are 36" panels, the first roll is 4' wide and the subsequent rolls are 6' wide, so the seams are staggered from the panels. Buy the rolls with the 6" vapor barrier "tab" that overlaps and tapes to the previous roll. It's laid between the panels and the purlins as you put the metal on. Don't pull it perfectly taught and let it blowse/sag a bit between the purlins for maximum insulating performance.

Fiberglass Batt Rolls

 

[miscjames]

If I was doing a metal building, I'd use the 3" fiberglass batt R-10 rolls (or thicker for more R) with the white reinforced vapor barrier that they make for the purpose. If the walls are 36" panels, the first roll is 4' wide and the subsequent rolls are 6' wide, so the seams are staggered from the panels. Buy the rolls with the 6" vapor barrier "tab" that overlaps and tapes to the previous roll. It's laid between the panels and the purlins as you put the metal on. Don't pull it perfectly taught and let it blowse/sag a bit between the purlins for maximum insulating performance.

Fiberglass Batt Rolls

Sounds like a good plan. However i had a summer job in Florida. Where i made fiberglass ac duct and installed them. To this day i still dont like messing with fiberglass insulation. I can remember having to take cold showers just so the fiberglass wouldn’t go deeper in your skin. Of course that was decades ago. So it might be better now.

 

[gsganzer]

Sounds like a good plan. However i had a summer job in Florida. Where i made fiberglass ac duct and installed them. To this day i still dont like messing with fiberglass insulation. I can remember to having to take cold showers just so the fiberglass wouldn’t go deeper in your skin. Of course that was decades ago. So it might be better now.

I hate everything about fiberglass, except its insulating properties.