I am building (DIY) a house with crawlspace walls formed with ICFs. The building inspector says the exposed foam walls need to have a fire barrier. I can use sheetrock but as I am doing this myself I am concerned that it may get wet before I get the building framed and enclosed. Any alternative ideas? Would the cement board used behind woodstoves etc. work – and how expensive would it be? Any ideas are appreciated.
Thanks,
Steve
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Arxx ICF's are fire rated and don't need to be covered. Drywall later would be a pain but probably the cheapest way. Maybe Durarock or wonder board would work and wouldn't be a problem if it gets wet. I am building my new house with icf's for crawl and having an unventilated conditioned crawl space. The fire rating is one of the main reasons I'm using Arxx forms. Good luck
I just spoke with the guy I'm getting my forms from. He will be checking to see if they will meet the fire code here. That would be too easy though!
The Rastra-type gridwall forms carry a 4-hour rating, unparged. They are composed of styrene foam beads (recycled foam) bonded in a matrix of Portland cement. Just another possibility to consider. Bugproof, too.Bill
Will the top of your footing be exposed? What climate do you live in? I'd be concerned that sheetrock down to earth would be asking for the sheetrock to decompose from moisture over time. That wouldn't be a problem if you live in the desert, maybe. If the top of the footing is exposed and reasonably moisture free I suppose it'd be fine. Or use WR rock for a bit of improvement.
If you're going to rock it, you could at least set a few blocks in the crawl space and stock the rock before you build the floor.
Better yet, parge it.
I'm thankful for the loyal opposition! It's hard to learn much from those who simply agree with you.
The concerns you bring up are mine exactly. I will have to backfill the inside to within approx. 2 foot of the top of the wall and then cover the remaining exposed ICFs with the fire barrier. Sheet rock just dosen't seem to be a good idea.
Welcome to BT. It can be a bumpy ride so hold on!!!
Aren't most ICFs fire rated? I really have no idea.
I wonder what the fire rating is on Hardie Backer? I can't remember if it is cheaper or more expensive than regular cement board.
Here is another off the wall thought: what about that cementous (I think) fire retardant coating you see sprayed on structural steel in commercial buildings? Years ago I worked for an insulation contractor who sprayed that stuff...
Also, what is your logic in building a crawl space out of ICF? Is the ICF to extend up to the roof line?
Use the search function here at BT. There have been several (many?) discussions about ICF here in the past. You may want to find out more bracing them.
Good Luck,
I'm using the ICFs in order to be able to do the work myself. I have already used them in the past when building a 4-plex with 8' walls.
The guy I'm buying them from just finished his son's house with walls approx. 20' tall with ICFs. He is going to help me and we'll use his braces, etc. so that will be the easy part.
Steve,
Welcome to Breaktime!!
If you click on your name above (where it says "To: 5brown1"), you will open your profile.
We would appreciate it if you could fill some of that in, especially where you are located!!
Thanks!
Rich Beckman
Another day, another tool.
Filled in the profile. I am actually in the rental business. I've been renovating and selling or renting houses for the past 20 years. I have also designed and built a 4-plex and 4 duplexes for myself over the past few years. Thanks for the welcome.
How about just pealing off the inside foam? You would loose insulation but solve your problem.
You get out of life what you put into it......minus taxes.
Marv
Edited 1/3/2005 5:32 pm ET by Marv
I told my supplier that some forum members have ICFs that are fire rated and may not need a barrier. He called the manufacturer who said that they did not know of any place that required a fire barrier in an area which is not a habitable space. Also said that the ICFs have a 3hr rating and will not produce noxious gases when burned. Anyway, I will see what the building inspector says about that.
Peeling the foam off is certainly better than putting sheetrock on the walls. There would still be 2.5 in. of exterior insulation. I would prefer to leave it but the thanks for the idea.
Personally, I think it would be a lot easier to parge coat than to peel the interior insulation off.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
I am not familiar with parge coating. Is this similiar to a stucco?
One other consideration is that it will be quite cold here for the next couple of months and I need to get this issue taken care of before I begin framing otherwise it will really be difficult to do. I
Parge is a plaster coat of mortar - like stucco, sometimes with wire lathe. Most manufacturers of ICFs sell a modified acrilic portland coating that you can mix and trowel on. I don't see why you couldn't do that in a crawl space after floor framed. Too low?
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Thanks for getting back to us. A lot of people put these Qs out there and then never let us know what turns out.
You said: >> He called the manufacturer who said that they did not know of any place that required a fire barrier in an area which is not a habitable space. <<
I believe the IRC requires fire barriers on foam for anyplace that is accessible and contains any serviceable equipment/utilities/etc. I have no idea what code is in force where you live. 3 hr fire rating with no fumes sounds pretty good though, and I'd think a letter from the manufacturer stating what you said above would satisfy the inspector. I think the fumes is the issue...
You said that you wanted to use the ICF because it would be something you could do yourself. Around here, an 8" block wall goes for around $3.25 for a square foot of wall - turnkey. I wonder what the approx cost is of the ICF block is once you figure in the concrete, pumper truck and bracing? Matt
I also wanted the insulation factor and not have to try to insulate it later. We do get COLD here. Right now it is about 9 degrees with a 15-20 mph wind -- that's why I'm still inside.
I've been looking at suggestions here and am going to do the unvented crawl space. QUESTION: If putting a duct into the crawl space for heat or cooling won't there need to be a return air opening in the crawl space also?We can't do block in this area as the soil movement just breaks them apart. Also I will not need a pumper for this job and the supplier of the forms has all the bracing which I will use at no cost. I used my skid loader to dig in the footings which are now done and I believe that I will save at least a couple grand over having a contractor do it. Additionally the concrete will be stronger in the ICFs and I won't have to insulate.
Edited 1/4/2005 10:51 am ET by 5brown1
Sounds like you got it all under control...
That's interesting about the soil conditions. I did not know SD had thoes type of problems.
Re the weather, we are having a record breaking warm snap here in NC. It may reach 75* today!!! Sweeeeeeeeeeeeeeeeet!!! I will be pouring concrete within the next few days and it looks like I'll be saving some $$ on freeze protection. :-) Matt
"If putting a duct into the crawl space for heat or cooling won't there need to be a return air opening in the crawl space also?"From stuff I've read here and there...No one bothers to seal the crawlspace ceiling.It would be an unusual house indeed that did not have myriad opennings in the crawl ceiling for air to move from the crawl into the living area.If you install a fan moving air from the living area into the crawl and do not install a return air you will be (ever so slightly) pressurising the crawl. Air will find its way back into the living area through the opennings. But I suspect that a pressurized crawl is not necessarily a bad thing.All of this assumes that the sealing of the crawl is properly (thoroughly) done.Again, this is from what I've read.Rich BeckmanAnother day, another tool.
Welcome to breaktime. There are a small group of us in the same business you are.
Tim Mooney
sounds to me like your inspector's never seen ICFs & is doing a CYA...can't imagine a good reason for a fire rating in a crawl space (does he want fire code drywall under the floor joists, too?).....if you can't change his mind slap some Durock on it...what are you putting on the outside?....
Im an inspector at the present time . I operate out ot the NFPA which has 15 volumes.
Ive never heard or read this and I think I would require the inspector giving me the code in question. Show me.
Tim Mooney
Thanks for the input. I hope to see him again today.
I don't know what the NFPA is, but here in NC we use a flavor of the IRC. Today I was looking for something else and came across paragraph R318.2.3:
http://www.amlegal.com/nxt/gateway.dll/NC%20Residential%20Code/part00382/chapter00383/section%20head00494/section00498.htm/subsection00501.htm?fn=main-nf.htm$f=templates$3.0
Of coarse, I don't what code other states use. Matt
I haven't had a chance to get back to him as I had a couple of furnaces acting up yesterday along with some show to shovel. Hopefully I'll see him today. On the outside I'll only have 6" above grade and am considering a stucco finish of some type.