Insulation between studs or on top? Metal building

[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.