Roxul ComfortBatt - Manual (Page 20)

20
Better | Best
Thermal insulation systems
for crawl spaces.
Many home and cottage owners can enjoy additional
benefits by insulating their crawl spaces. In some
cases, the most difficult aspect of insulating a crawl
space is having enough room to work around to
properly install the insulation. If the crawl space area
is easy to get at, the installation of ROXUL
® insulation is
quite simple.
Typically, there are two types of crawl spaces – they
are defined by either being vented or non-vented.
The difference in how the two crawl space types are
insulated is defined by either applying insulation to
the exterior wall, or to the ceiling/floor between the
heated living space and the crawl space.
Non-Vented Crawl Spaces (page 21)
A non-vented crawl space is defined as having a
heating or cooling source, or some other source that
conditions the air within the crawl space. Conditioning
the room helps to manage the relative humidity
in the space, and helps to avoid the growth of mold.
We would treat insulating a non-vented crawl space
in the same manner we do a conditioned basement.
The exterior foundation would be framed in with
studs and then insulation would be installed
between the studs.
Vented crawl spaces (page 22)
Vented simply refers to the space having air vents,
typically more than one, and are generally located
across from one another at the upper part of the
foundation wall. The vents allow for air movement,
helping to eliminate dry rot, moisture build up, and
other conditions that can develop in these enclosed
spaces. This type of venting would be very common
in a lot of older homes.
With a vented crawl space, it would be treated in the
same manner as a cantilever, or insulating a room
of your house where the underside is exposed to the
elements. The underside of the floor would then be
insulated by adding batt insulation between the
floor joists.
ROXUL Insulation: a two-tiered solution
to insulating crawl spaces
ROXUL has two thermal insulation products
for interior crawl space wall assemblies:
ROXUL COMFORTBOARd
™ IS (Insulation Sheathing)
and ROXUL COMFORTBATT ® . When used in tandem
within the 2 x 4 stud wall cavity, these two products
help create a more comfortable space.
A vented crawl space can be notorious for dampness,
but ROXUL insulation is water repellent, moisture
resistant yet vapor permeable. The permeance of
ROXUL products allows moisture vapor to pass
through the insulation without being trapped. In the
unfortunate event of a flooded basement where the
insulation becomes wet, ROXUL insulation quickly
dries out and maintains its R-value. Unlike other
insulations, ROXUL won’t absorb water and is not
susceptible to mold growth.
COMFORTBOARD ™ IS and the effects of
thermal bridging
Before recommending the Better I Best R-values for
the crawl space wall assembly, we need to understand
thermal bridging – the process that describes a
material’s capacity to conduct heat or cold from
one material to another.
In a typical crawl space, thermal energy transfers
from the wood studs and interior of the concrete
foundation into the exterior foundation and
surrounding soil. The studs perform as the conduit
or “thermal bridge”, lowering the effective R-value
of the wall assembly. Insulated sheathing like
COMFORTBOARd IS reduces this thermal bridging
by acting as a thermal buffer between the concrete
and the studs.