I have a question about the interior coverings for a crawlspace.  As I understand it, if one is looking to put a furnace (or anything electrical) in the ICF crawlspace of a home, then the EPS must be covered with gypsum or some other type of 20 minute fire wall.  Does anyone know if there is a better/easier/cheaper product out there that can be used instead of gypsum?  Also, if the furnace is isolated in the crawlspace (with a covering) can the remaining EPS remain exposed?  Apparently, in Virginia building officials see this differently from county to county and I would love for find an easy way to remedy this.

Any input would be greatly appreciated.  Thanks.

renangle

renangle,

IRC 314.1.2 and more specifically IRC 314.2.3 deal with interior finishes of foam plastic. You can use gypsum or they have a list of other coverings. You can also find cementisious coatings that can be sprayed on that meet the ASTM E 119 standard time temp curve.

ICF Contractor

The following are direct from "The Prescriptive Method For Insulating Concrete Forms In Residential Construction, Second Edition":

From Page I-6 (Chapter 1 - General - Definitions)
Crawlspace: A type of building foundation that uses a perimeter foundation wall to create an under floor space which is not habitable.

From Page I-16 (Chapter 3 – Foundations)
3.3 ICF Foundation Wall Coverings
3.3.1 Interior Covering
Rigid foam plastic on the interior of habitable spaces shall be covered with a minimum of 1/2-inch(13-mm) gypsum board or an approved finish material that provides a thermal barrier to limit the average temperature rise of the unexposed surface to no more than 250 degrees F (121 degrees C) after 15 minutes of fire exposure in accordance with ASTM E 119 [19].

From Page I-28 (Chapter 4 – Above-Grade Walls)
4.2 ICF Above-Grade Wall Coverings
4.2.1 Interior Covering
Rigid foam plastic on the interior of habitable spaces shall be covered with a minimum of 1/2-inch(13-mm) gypsum board or an approved finish material that provides a thermal barrier to limit the average temperature rise of the unexposed surface to no more than 250 degrees F (139 degrees C) after 15 minutes of fire exposure in accordance with ASTM E 119 [19]. The use of vapor retarders and air barriers shall be in accordance with the authority having jurisdiction.
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From this, only habitable spaces require the thermal barrier and crawl spaces are defined as not habitable so they don't require a thermal barrier.

Be careful though, local code requirements may vary.

bnc_skc,

I don't have this book in my library, but I would disagree with your assessment that a thermal barrier is not needed. The book you cite, in my jurisdictions, is not recognized as having any authority for the governance of construction. Although the verbiage is almost word for word out of the IRC what it is missing is the context that it is being sited.

My understanding of conditioned spaces is that if you put any heat producing device or appliance in the space then you will have to cover the walls and this come out of the IRC and the old UBC. Depending on where you are building these codes my not apply. The IRC gives you a list of approved coverings and they cite what testing proceedure a covering must meet to be applicable.

ICF Contractor

Question for debate, I agree that the space is unihabitable that drywall is not required, if it were my house, I would drywall it as inexpensive insurance, it acts as an air barrier and realistically that air barrier helps maintain the temperature fluctuations, meaning that in theory the equipment does not need to go through extreme temperature variations. For the debate, which we can all try to interprit, if you live in the southern area of the US, it is common practice to install HVAC equipment in the attic, other than the required clearances from combustables nothing is covered, wood roof rafters, pink insulation, all this wonderful stuff that burns nicely. So looking at that I would say without having a code book in front of me the crawl space does not require drywall. In previous experiences, I have had inspectors require basements be drywalled and taped, some just required drywall no tape, and others not even care if the ICF wall was even covered. The local inspector is not always right, but has the final say.

Chris