I want to convert my vented crawl space into a sealed/conditioned crawl space. I want to do this by covering the walls in foam panel insulation after sealing the vents.
I’m confused though by what I’ve seen is a requirement to have a “fire barrier” over the foam panels in order to meet code. However I’ve also seen it mentioned that as long the crawl space is not used as habitable space (which it can’t be anyway) that the “fire barrier” does not apply.
I’m not that knowledgable about codes and safety required so I’m hoping you guys can help me determine what is the right way to tackle this. Here’s some information that may help:
Access to crawl space is external only.
No combustion appliances (only 1 electric storage wh).
The information I found in my city’s online ordiances are:
(a) As of October 1, 1991, amended July 1, 2004, the following construction codes, as amended by the State, became mandatory as the Georgia State Minimum Standard Codes and each, except as amended hereby or by subsequent ordinance, shall provide the minimum standards for the city:
(1) International Building Code;
(2) International Fuel Gas Code;
(3) International Mechanical Code;
(4) International Plumbing Code;
(5) National Electrical Code;
(6) International Fire Prevention Code;
(7) International Energy Conservation Code;
(8) International Residential Code for One- and Two-Family Dwellings;
(9) Georgia Accessibility Code (O.C.G.A. Title 30 Chapter 120-3-20);
(b) Wherever referred to in this chapter, the codes provided in subsection (a), above, shall mean the latest edition of such codes as adopted and amended by the Georgia State Department of Community Affairs.
Replies
There is a product called, I believe, Thermax. It is, more or less, a foam panel with a foil veneer. I am told it gets used a lot in pole barns.
Whether or not that meets code for the crawl depends on the local inspector's opinion.
I have seen at least one article where the author claimed that he was able to satisfy his local authorities with Thermax.
Rich Beckman
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We can use unfaced ridgid foam panels
This web site might be helpful: http://www.crawlspaces.org .
Dow Thermax is the foam board of choice in many crawl spaces as it does meet code requirements - in my state anyway. Codes involve stuff like flame spread ratings and smoke-development ratings. These ratings are normally printed right on the rigid foam in question. No stamps - no use.
Calling your local inspections department would be your best bet. The reason they don't want certain foam plastics exposed in a crawl space is that it gives off poisonous gases when burned. So, if somehow, a fire started in your CS, you and your family could die. Might as well do it as the local officials want it.
BTW - you also likely need to use a termite inspection strip. Check into it.
Up here in Michigan, I use 2" rigid insulation in my crawlspaces and i'm required to cover it with 1/2" drywall by the building inspector. Its not too big a hassle, just use a water based adhesive and glue it on.
What is a "water based adhesive "? Only one I can think of, right off hand, is wood glue... I'm thinking that isn't it. :-) Do you use misture resistant drywall? Do they make you do any finishing on it?
By waterbased adhesive I mean foam board or "project" construction adhesive. We put 6 mil on the ground so no I dont use moisture resistant DW. As far as seams we're not required to tape seams (which always seemed odd to me).
The whole thing seems kinda gratuitous, they dont ask for taped seams and at the top of the insulation they dont require covering up the exposed edge. I guess I shouldnt complain though, I prefer not spending too much time in the dungeon.
How are you attaching that foamboard and 1/2" drywall "sandwhich" to block walls? Powder-actuated fastners with plastic washers or are you glueing the whole package to the block? If so, any problems with adhesive failure from the combined weight?
I was hoping someone could interpret the local code for me because I'm almost afraid to speak with the BI office since sealed crawlspaces are a relatively new idea that they may not have "accepted" yet.
Oh, and since I am the HO I would be doing the work myself and not obtaining a permit since we're just dealing with insulation. I do however don't want a future home inspection to red flag the insulation for not meeting code though.
Thinking aloud... I wonder what the cost difference is between 2" Dow Thermax and 2" <insertbrand> foam board with 1/2" drywall.
Depends on where we are in the crawl. With the last house we were able to use adhesive and friction (between the footing and bottom of the floor joists). I didnt personally install the last time but I do think we had a couple of areas that required mechanical fastening. We just used tapcons which helped hold till the glue set.
" I wonder what the cost difference is between 2" Dow Thermax and 2" <insertbrand> foam board with 1/2" drywall."I don't know the price differences, but there is another alternative to consider: whatever thickness of foamboard you want with 1/2" Thermax on top of it.Rich BeckmanThis signature line intentionally left blank.
Thanks Rich, I've thought of that myself too.
My original question is moot at this point since I want to do whatever is safer for my family, be damned what the codes are. Fire-rated or fire-barrier is the way to go.
Does anybody know if the big box stores sell Thermax or is this an item I'm likely going to have to find a specialty supplier for (I live in the Atlanta metro if that helps)? I've searched the Dow site for dealers but I guess that link is broken.
BTW: I've ruled out fiberglass batt blankets for this project because I believe they're a joke in the face of better technologies such as foam.
"Does anybody know if the big box stores sell Thermax or is this an item I'm likely going to have to find a specialty supplier for..."In my town, Carter Lumber (the chain) carries Thermax. I don't believe anyone else locally carries it.Rich BeckmanThis signature line intentionally left blank.