Just started looking into these, trying to think of some disadvantages. i wouldn't fully trust them to air seal 100% without taping the seams or liquid applied air barrier. Cost wise they don't seem to be too far out of reach. I'm also interested in using them below grade (only 4-6ft underground) I'm up in Kelowna BC Canada and found this supplier so far www.gsbp.ca the search function seems to not be working for me, i did find some talks on the forums about thermasteel with a google search.

You can also follow along using minimally expanding foam in all the seams as well.
I'd probably do the MEF along the bottom track and on each side of the SIP during assembly.

1: Spritz a zigzag on the bottom track under where the first panel goes.
2: Install the first panel.
3: Run a zigzag down the side panel #1 and along the track where #2 is going to go.
4: Install second panel.
5: Rinse and repeat until done

Followup. MEF the top of the panels before putting a top plate/cap/etc down on them.

Or you could peel&stick the entire assembly with an air and vapor barrier.

Note: I don't know that they're rated for sub-surface use.
Everything I see from them is SIP-on-concrete construction.
And, even if they are, I don't know that I'd trust them without EXTENSIVE, obsessive soil engineering, waterproofing and reinforcement..

I don't know that they're rated for sub-surface use.
Everything I see from them is SIP-on-concrete construction.
And, even if they are, I don't know that I'd trust them without EXTENSIVE, obsessive soil engineering, waterproofing and reinforcement..

i think they would probably put the steel studs on really narrow centers and or bump up the gauge. If i used them below grade it would be a shallow depth.. primer, peal and stick and dimple with 3/4" clean back fill. The rep told me they were rated to 8' below grade.

The problem is, Thermasteel panels aren't fully faced the way other SIPs products are.
They're more a steel framework which has foam board inside it.

https://www.gsbp.ca/community

Look at the images of the panels there.

You can't have a subsurface wall built that way.
Sure, the steel frame will (probably) hold.  But the exposed foam?  Nuh-uh.  Not a fargin' chance.

But don't take my word for it.  Call Greenstone or Thermasteel directly and ask if their panels are rated for subsurface/basement exterior wall applications.

http://www.greenstonepanels.ca/wp-content/uploads/2017/11/FOUNDATION-DETAIL.pdf

looks like they want you to put 1/2" ply over it.

So wood, even ground-contact-rated...on a subsurface wall.

Yeah.  No.  It might be strong enough.
I'd never do it.  And I'd never advise anyone to do it.

Posted By Dilettante on 11 Nov 2018 04:33 AM
So wood, even ground-contact-rated...on a subsurface wall.

Yeah.  No.  It might be strong enough.
I'd never do it.  And I'd never advise anyone to do it.

PWF has a long history of success and is a well established part of the building code here. Canada Wood Council Link: apparently I can't link here...

maybe a place to use recycled plastic lumber anywhere it contacts ground

wrong forum

Posted By Egbert on 13 Nov 2018 03:58 PM

Posted By Dilettante on 11 Nov 2018 04:33 AM
So wood, even ground-contact-rated...on a subsurface wall.

Yeah.  No.  It might be strong enough.
I'd never do it.  And I'd never advise anyone to do it.

PWF has a long history of success and is a well established part of the building code here. Canada Wood Council Link: apparently I can't link here...

Sure.  And I've seen nasty failures in PWF as well.
Not "let's fix this" failures.
"We need to rip the house down and rebuild from scratch" failures.

Things where people completely underestimated soil and hydrostatic pressures in the walls, etc.

Maybe your experience with PWF is different from mine.
But I've seen enough problems with sub-surface PWF that I'd never use it myself and would simply pass on any jobs requiring/involving it.