Page 10 - CodeWatcher Spring 2017 Issue

Energy Code Minute

“I Don’t Wanna!”

Easy solutions to diffuse the “Crawlspace Fit.”

Y kids as they pitched a fit, especially if it the floor decking, yet “don’t wanna” use a thermal barrier
BY STEPHEN CARR For those installers who want to spray closed cell foam under

OU HAVE HEARD this line from your

under the joists, you can apply the ignition barrier under the
had to do with a task that added a delay
SPF as long as the crawlspace has limited access and is not
to play time. Or, for those of you with
occupied. (See Figure 316.5.3)
teenagers, delayed gaming, hanging
In crawlspaces where the joist headers (rim joist) and sill
out with friends, or just plain being
lazy teens.
Spoiler alert! Even though we are not
requirements to consider (see Figure 316.5.11):
kids anymore, we all still say “I don’t wanna” (or at least are going to be spray foamed, there are some additional
think it) when it comes to adding extra time and money on R316.5.11 Sill plates and headers. Foam plastic shall be
our projects. permitted to be spray applied to sill plates and headers or
In my world over the past few months, the popular pitched installed in the perimeter joist space without the thermal
fit has been: “I don’t wanna install a thermal barrier in this barrier specified in Section R316.4 subject to all of the
crawlspace over my spray foam.” following:
Let’s take a time out and think about what we are stomping 1. The thickness of the foam plastic shall be not more than
our feet at. It comes down to “occupancy” and “storage” in 3 1/4 inches (83 mm).
the crawlspace. I am using 2015 IRC Section R316 Foam 2. The density of the foam plastic shall be in the range of
Plastic to illustrate. 0.5 to 2.0 pounds per cubic foot (8 to 32 kg/m3).
If the crawlspace is readily accessible and you can or are 3. The foam plastic shall have a flame spread index of 25or
planning on storing “stuff” in that space, then you will need less and an accompanying smoke-developed index of 450 or
to install a thermal barrier on the spray foam (SPF) or on the less when tested in accordance with ASTM E84 or UL 723.
interior of the assembly.
If you are not occupying or storing anything, then the Number 1 is where many builders have an issue. If the install-
following sections are your guide: er exceeds 3-¼ inches then he must apply a thermal barrier.
Otherwise under this depth, it’s common for installers to use
R316.5.4 Crawl spaces. The thermal barrier specified in Sec- the SPF density mentioned here and having the flame spread
tion R316.4 is not required where all of the following apply: requirements met while allowing an ignition barrier only.
1. Crawl space access is required by Section R408.4. Since the thermal barrier is required between the SPF and
2. Entry is made only for purposes of repairs or mainte- the conditioned space (R316.4), simply limit the access and
nance. do not store “stuff” in the crawlspace.
3. The foam plastic insulation has been tested in accor- The code also allows for SPF material having Specific
dance with Section R316.6 or the foam plastic insulation is Approval (R316.6) where it has already gone through testing
protected against ignition using one of the following ignition verifying it does not need an ignition barrier. So know your
barrier materials: products and look up the ICC-ES Report or Third Party
■ 3.1. 11/2-inch-thick (38 mm) mineral fiber insulation; Testing reports to identify material characteristics as the
■
■ 3.2. 1/4-inch-thick (6.4 mm) wood structural panels; material itself may save you a fit.
■
■ 3.3. 3/8-inch (9.5 mm) particleboard; I hope this time out resolved your crawlspace fit. Now go
■
■ 3.4. 1/4-inch (6.4 mm) hardboard;
■ play nice with your industry friends. CW
■ 3.5. 3/8-inch (9.5 mm) gypsum board; or
■
■ 3.6. Corrosion-resistant steel having a base metal thick- Stephen Carr is Regional Building Science Manager for TopBuild Home
■
ness of 0.016 inch (0.406 mm). Services. Have questions? Email him at stephen.carr@topbuild.com.
10 CodeWatcher / Spring 2017 www.codewatcher.us