Which foam board?

[tom-ky]

Which one of these foam boards would be best and why?


https://www.menards.com/main/buildi...46-c-5779.htm?tid=-5029212967468770510&ipos=9


https://www.menards.com/main/buildi...07-c-5779.htm?tid=-5029212967468770510&ipos=3

 

[Leaflessshadetree]

What are you using it for?

 

[lakeroadster]

Use Polyiso. It is much more flame resistant than Polystyrene.

 

[tom-ky]

What are you using it for?

My pole barn garage was built with just the double bubble insulation on the walls, thought about putting foam board to add some insulation value. I wanted to slide in in between the 2x6's that run horizontally so it will be behind the posts.

 

[stm317]

I just did what you're planning, and went with foil faced polyiso. The foil facing will add a little r value, and protects the insulation a bit vs the unfaced, pink EPS. I'd suggest 1.5" thick so that the foam is the same thickness as your girts and there is no gap between the posts and the metal. It fits perfectly. If you look on your local craigslist, you might be able to find it much cheaper than what Menards sells it for. I think Menards priced the 1.5" stuff around $26/sheet, and I ended up paying $15/sheet on Craigslist.

 

[tom-ky]

I just did what you're planning, and went with foil faced polyiso. The foil facing will add a little r value, and protects the insulation a bit vs the unfaced, pink EPS. I'd suggest 1.5" thick so that the foam is the same thickness as your girts and there is no gap between the posts and the metal. It fits perfectly. If you look on your local craigslist, you might be able to find it much cheaper than what Menards sells it for. I think Menards priced the 1.5" stuff around $26/sheet, and I ended up paying $15/sheet on Craigslist.

Only thing I found on Craigslist close to me is 1 1/2" in 4x4 sheets.
Menards doesn't stock the 1.5" either.

 

[tom-ky]

Also I wonder if condensation would form between the foam board and the bubble wrap?

 

[Loose Ctrl]

Use Polyiso. It is much more flame resistant than Polystyrene.

 

[Loose Ctrl]

Also I wonder if condensation would form between the foam board and the bubble wrap?

If there's an air gap, yes, it's very possible.

 

[wreckingba11]

higher the R value the better ,have you consider spray foam ??

 

[toyotadriver]

Polyiso does drop in R value when the temps really drop. It also drops in R value as it ages. The R value of XPS (the pink stuff in your link) remains constant.

I did basically what you are planning to do but did it during initial construction. Worked fine.

 

[tom-ky]

If there's an air gap, yes, it's very possible.

I planned on it being right up against the bubble wrap.

 

[tom-ky]

higher the R value the better ,have you consider spray foam ??

I got one quote and they were using open cell for $1.35 a square foot, seem high to me. Really just wanted to put up the foam board and not have to finish the interior walls, the spray foam would look rough without something over it.

 

[toyotadriver]

I planned on it being right up against the bubble wrap.

I'd use the pink foam sheets.

 

[toyotadriver]

Double tap