Putting up walls in the basement

[Charlotte987]

So, our insurance co has told us that we have to cover our basement walls with something that will slow down a fire, we have a full size wood-burning Fischer in the basement and an electric furnace as well. The walls are quite thick rubble stone covered with several inches of spray foam that has been painted. The insurance co has told us that if there is a fire, the basement spray foam on the walls will cause a lot of carcinogenic smoke, so they have to be covered over.

The real problem is this, how do we attach wall studs to several inches of spray foam and the stone walls? Spray foam is not strong enough to attach to, it breaks into pieces. Drilling into the spray foam in some places where its several inches thick, you hit a soft rubble wall at times, is there a special kind of drill bit for drilling into spray foam? The only thing we can think to do, is to first drill into the spray foam, and then change bits to drill into the rubble stone walls.

Has anyone ever done this before? If you have how did you attach the wall studs to the spray foam?

 

[Jags]

Have you considered moving out a couple inches from the foam and doing a proper stud wall? This might be the easiest and yield the best (read: straightest) wall in the end. 5/8" sheetrock (drywall) is Fire Coded. I am not sure why there would be...but if there is a specific fire code rating needed - that is pretty simple engineering. Maybe consider steel studs (easy to work with) for additional fire proofing.

 

[Charlotte987]

There are of course problems with that, and you are right about wanting (greatly desiring) a straight wall in the basement. Where everything bulges out with spray foam and nothing is straight. The floors are carpet covered half inch plywood, over several inches of spray foam, which is on top of a pored concrete. The ceilings are the spruce subfloor covered with what I think my grandfather called 'beaver board' (I have no idea what that is, looks like some sort of manufactured wood product).

So I'd have to attach a sill plate to the floor and attach wall studs to that right? Only another problem comes up, the upper floor joists drop down about six inches, they are massive and hold up the entire two stories above. So I guess I'll simply have to work around them.

 

[sportbikerider78]

Have you considered moving out a couple inches from the foam and doing a proper stud wall? This might be the easiest and yield the best (read: straightest) wall in the end. 5/8" sheetrock (drywall) is Fire Coded. I am not sure why there would be...but if there is a specific fire code rating needed - that is pretty simple engineering. Maybe consider steel studs (easy to work with) for additional fire proofing.

The only issue with that is then you have created another gap were moisture can hang out, critters can run around in and spiders and stuff to chill out in.

If it was me, I'd do exactly what Jags posted, but then use more spray foam to fill the gap. I might be over the top, but everything I have read says that gaps and basement walls is a bad thing.

 

[velvetfoot]

Can't you get specs for special fire-resistant paint and show that to the insurance company for its approval? And get another insurance company if they balk.

 

[DougA]

http://www.homedepot.com/p/ForceField-FireGuard-E-84-5-gal-Intumescent-Primer-FFGD-E84-g05/203582028

A bit expensive but lots cheaper than putting down a new floor and walls.

 

[xman23]

I have seen fireproofing coating applied to wood. Kind of thick encapsulating coating. I would think you could spray on something that says it's now fireproof.

 

[Ambient]

Have you considered moving out a couple inches from the foam and doing a proper stud wall? This might be the easiest and yield the best (read: straightest) wall in the end. 5/8" sheetrock (drywall) is Fire Coded. I am not sure why there would be...but if there is a specific fire code rating needed - that is pretty simple engineering. Maybe consider steel studs (easy to work with) for additional fire proofing.

I've finished many a basement. The paint may sound like a easier way, but for EACH 7 foot by 12 foot wall , (86 sq ft coverage) per $325 pail of paint it would be much cheaper to erect a 5/8 sheetrock wall. Spray foam isn't allowed to be exposed anywhere in the US under codes, it must be covered to withstand up to 1/2 an hour. Each building department has their interpretation of that rule. Where I live now 1/4 luan was the code enforcement officer's suggestion for a portion of new basement with NO heat source. If you stud every 16 inches O/C you could add more fiberglass insulation if you desired.

 

[Jags]

So I'd have to attach a sill plate to the floor and attach wall studs to that right?

For non-load bearing, yes - you would put a bottom and top plate (or runner or whatever the term is in your neighborhood) and then stud it up.

 

[DougA]

The floors are carpet covered half inch plywood, over several inches of spray foam, which is on top of a pored concrete

I just don't see attaching a stud wall to 1/2" plywood as a base, especially when the plywood is not really attached to anything but foam. IMHO, Charlotte would have to build a stud floor too and anchor it through the foam onto the concrete, otherwise everything is floating on foam. The best alternative is to drill an anchor through the foam wall into the stone and that would make the wall more secure. You wouldn't need too many.

 

[Ncountry]

I would do like Jags suggested. Personally I wouldn't use steel studs due to potential moisture problems. Put a pressure treat plate on floor and go up from there. Do not set drywall directly on floor(capillary action)

 

[Swedishchef]

I spray foamed my concrete walls when I built. Yes, they are not perfectly smooth..BUT, +-.5 inches is about all they're out. I studded with a treated base plate, framed all the way around the entire basement. I then added Roxul (fireproof and considered a fire barrier) and then gyprocked. The roxul actually isn't perfectly flush with my gyprock but it is added insulation for cheap.


Andrew