[Greenbuilding] Code Compliance Floor floating on Foam

John Salmen terrain at shaw.ca
Wed Apr 2 11:07:15 MDT 2014

I'm not familiar with the current IBC but wood is typically allowed based on
thickness - so typically a total wood floor thickness of 1.5" (subfloor plus
finished wood floor) would meet the fire assembly rating. Or in the case of
tile there would be an intermediate layer of cement board that would
qualify. Gypsum board is also allowed... so not sure what the issue is.


Get an eng. to sign it off the detail - that is generally the only
workaround for a recalcitrant inspector for a detail not specifically
referenced in the code.


From: Greenbuilding [mailto:greenbuilding-bounces at lists.bioenergylists.org]
On Behalf Of Dan Johnson
Sent: April-02-14 9:35 AM
To: Green Building
Subject: Re: [Greenbuilding] Code Compliance Floor floating on Foam


The 2013 California Building Code is also based on IBC but contains this

2603.4.1.14 Floors. The thermal barrier specified in
Section 2603.4 is not required to be installed on the
walking surface of a structural floor system that contains
foam plastic insulation when the foam plastic is
covered by a minimum nominal 1/2-inch-thick (12.7
mm) wood structural panel or approved equivalent. The
thermal barrier specified in Section 2603.4 is required
on the underside of the structural floor system that contains
foam plastic insulation when the underside of the
structural floor system is exposed to the interior of the

Dan Johnson | Design and Energy | 510.325.5672

Assoc. AIA, ASHRAE, LEED AP, CEPE, CPHC | 5500 Kales Ave. Oakland California


On Wed, Apr 2, 2014 at 8:15 AM, <conservationarchitect at rockbridge.net>

Thanks for reply on EPS sealants suggestions.

I am having difficulty with a code official that believes unless an assembly
is referenced in the code, it is not allowed.  At issue is my proposal to
float  2 layers of 7/16"osb over EPS foam.  The osb will have staggered
joints and be fastened to each other with screws.  The 09 Virginia Building
Code which is the same as the International Building Code states in 2603.4
Thermal Barrier over foam can be achieved with 1/2"gwb or equivalent per
test protocol.   So I propose to add 1/2 gwb above foam below osb.  Because
he has not seen that assembly before, he is threatening to block it because
I can not find a code that explicitly describes my assembly.  With him
disputing the explicit remedy describe in the code, what are my chances?
$@!#^& Peace, Love

Have other list participants faced similar issues with code officials
regarding the thermal barrier cover over foam.

Otherwise, I am interested in hearing stories of challenges we have
experienced creating innovation in a code limited paradigm.


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