I was planning on using ICF for my crawl space foundation walls.  Based on some conversations with the local inspection folks, I am led to believe that the foam insulation on the interior of the crawl walls will need fire protection (1/2" wall board).  This took me by surprise and wondered if the folks that are experienced with ICF have run in to this.

At first it didn't seem like such a big deal, as it would be easy to attach the sheet rock to the provided webs and tape.  Then it occurred to me that there is also the 2.5" exposed top surface and a 2.5" surface resting on the footing.  Assume nothing is required at the footing interface, but what about the top surface?

Anybody have any ideas if this surface also needs to be protected?  How do you attach  drywall there?  Is my assumption about the bottom surface valid?  Also, do you use regular sheet rock or the green board; I plan to carefully detail and use accepted practices for moisture control, but it is still a crawl space.  Thanks for any insights.

Here are the relevant sections from the 2006 IRC. They may have changed, but I doubt it. The minimum you can get by with is 3/8 sheet rock if the crawl space is not accessed except to service the house utilities. Otherwise you need to use 1/2", but considering that 3/8 board may not even be available, or may cost more than 1/2", 1/2" wall board is the most practical choice. Green board isn't available any more, I don't think. It's not permitted in wet areas like bathrooms any more. I used weather resistant wall board in my crawl space only because I put it in after the ledger plates were in and before the floor was put in. That meant the crawl walls were exposed to the elements for a couple of weeks. Weather resistant wall board has black paper on it.

I don't know if any of the ICF block foams pass the fire test mentioned in the quote, or not. The blocks I used in 2008 did not.

R314.4 Thermal barrier. Unless otherwise allowed in Section
R314.5 or Section R314.6, foam plastic shall be separated from
the interior of a building by an approved thermal barrier of minimum
0.5 inch (12.7 mm) gypsum wallboard or an approved
finish material equivalent to a thermal barrier material that will
limit the average temperature rise of the unexposed surface to
no more than 250°F (139°C) after 15 minutes of fire exposure
complying with the ASTM E 119 standard time temperature
curve. The thermal barrier shall be installed in such a manner
that it will remain in place for 15 minutes based on NFPA 286
with the acceptance criteria of Section R315.4, FM 4880, UL
1040 or UL 1715.

R314.5.4 Crawl spaces. The thermal barrier specified in
Section R314.4 is not required where crawlspace access is
required by Section R408.3 and where entry is made only
for service of utilities and the foam plastic insulation is protected
against ignition using one of the following ignition
barrier materials:
1. 1.5-inch-thick (38 mm) mineral fiber insulation;
2. 0.25-inch-thick (6.4 mm) wood structural panels;
3. 0.375-inch (9.5 mm) particleboard;
4. 0.25-inch (6.4 mm) hardboard;
5. 0.375-inch (9.5 mm) gypsum board; or
6. Corrosion-resistant steel having a base metal thickness
of 0.016 inch (0.41 mm).
The above ignition barrier is not required where the foam
plastic insulation has been tested in accordance with Section
R314.6.

I take it you are only doing the crawlspace/basement with ICF and doing conventional framing above. If that is the case your sill plate will cover the top of the foam (2.5") and when you drywall the walls it will go from floor to u/s of joists. This small amount of foam will be covered by this sill plate on top and the drywall on the wall itself.

For what it's worth...the code says the ICF needs 15 minute fire protection I.e. drywall but keep in mind...it is never 100% covered, 99.9% yes but there will always be some small area still exposed or not actually covered to the full 15 minutes.

Thank you both for the info. My particular build is currently designed to use SIP floor panels which is attached to the sill plate. This would leave a 1.5" space between the top of the ICF foam and the SIP panel bottom OSB. I guess this would be easy enough to cover with a strip of wallboard between the sill and the edge of the ICF foam or to the edge of the vertical wallboard.

Most details I have seen show the 6 mil. vapor barrier on the crawl space floor show it running up the footing and wall some distance; and sealed everywhere. Would you run this vapor barrier up the wall before installing the drywall or after? Thanks again for the info.

Your below grade vapour barrier does not need to run up the ICF, you can run it up an inch or so and use tuck tape to seal it. Drywall goes on top.

Also consider EPS below the slab

And inch of poly is a pretty tight tab to seal- most people give it at least a foot rather than have to stretch the poly to make it on the far side of the space. A combination of duct mastic (between the poly & EPS) and tape (at the edge of the poly) makes for a better air and vapor seal than either alone.

In some instances it may be worth going at least up to grade-level with the poly to limit vapor migration through the EPS toward the interior, but in all cases the gypsum laps the poly, trapping it to the EPS.

EPS below the slab is well worth it in cooler climates, less so in US climate zone 3, and counterproductive on energy use for US zones 1 & 2 where the benefit of coupling the house to the thermal mass of the (roughly room-temp) subsoil is better than isolating it at typical ICF R values. This can change when taking R values and energy modeling to the PassiveHouse extreme.

Most of my customers are coating their icf walls with a 15 minute latex coating that meets code and is cheaper than sheetrock we have been using it for about 6 or 7 years with no problems with BI's

Smartwall, can you tell the name of that product?

Could someone be confused here?

The "Fireblocking Paint" compounds like DC-315 and similar are approved for polyurethane and icynene foams, both of which are 2-component foams that do not really melt. Most ICF is made from EPS or polystyrene foam which is one-component and will soften and melt at temperatures as low as 100C.

Is that "15 minute latex coating" really approved as a fireblock for EPS-containing ICF?

It's made  for eps as well as other foam products  I carry the test results in my prescriptive method binder.  As far as other spay in place foams the BI's in my area are requiring a 15 minute barrier in any retrofit attic spray job

What's the product called, and who makes it?

I carry the test results in my prescriptive method binder.

Has it been privately tested or are the results published?

Hey. Am I invisible here? What the F is this product called and who makes it? If it's some weird concoction you stirred up in your garage, let us know. If it'c commercially available, how 'bout a plug?

http://www.energsmart.com/spray-foam-insulation/firelok-thermal-ignition-barrier.html

http://www.thermal-contractors.com/pdf/ELASTOCOAT_1500.pdf

http://www.sprayfoam-mag.com/resources/industry-news/ignition-barrier-product-meets-building-code.aspx

http://www.idi-insulation.com/PDFs/spray-foam/materials/BaySeal/DATA_DC315.pdf

http://www.specjm.com/files/pdf/BID-0115.pdf

Pick one

They're all specified for application over polyurethane spray foam. Can anyone verify if they are approved over expanded polystyrene? If not, I will investigate and report back later.

I've yet to hear of an intumescent coating that was good for polyurethane but not polystyrene, but I s'pose there's always the possiblity of finding one.

This one specifically spells out both for the standard product, with a related product specific only to open cell low density SPF:

http://www.na.graceconstruction.com/product.cfm?mode=a&id=49&did=3

The Grace product is a spray-applied cementitious product. I would be surprised if it qualifies as being cheaper than sheetrock. Seems like the easiest thing to do might be to just hang sheetrock if you can get it to qualify without mudding and finishing.

Hey Ray, did you ever think of anger managment. I onyl read the last post off an Iphone so I answered it without scrolling up. Since you have been a bad boy anyone else wanting to know the name of the product I use can PM me.  Dana is right it,s not some magic potion it's intumescent paint, but like a lot of products not all work the same way or cost the same

Okay, so we've got intumescent paints approved for use over polyurethane foams, and cementitious products to go over EPS, and of course, good old sheetrock, but we are still waiting to see if we have a "15 minute latex coating" that can go over ICF, (essentially EPS) in order to meet regs?

Is there some reason the rest of us can't know what the product is without PM'ing?