by Steve
Easley
These days, it's not an exaggeration to say that almost all
homeowners expect their homes to be durable, energy efficient,
safe, and comfortable. But this is especially true in coastal
markets that cater to high-end clients who demand supreme quality
and impeccable performance from their homes. Even in today's
markets, which are euphemistically described as "relaxing," there
seems to be no shortage of wealthy home buyers snapping up
second-home properties along the coveted coast. If you build in
this market, it's this kind of discriminating home buyer who will
most expect you to get things right.
In more than 25 years of consulting with builders on ways to reduce
callbacks, I've spent most of my time solving problems related to
heat and moisture transfer through buildings, because this is often
where builders — even very good builders who deliver
well-appointed homes to the coastal elite — get things wrong.
Most of the serious (read "expensive") performance failures are
moisture related, and a good number of these are closely tied to
the thermal performance of the home. Yet I am surprised how often
the insulation is installed without much thought or understanding
about how it works. Consequently, very little attention gets paid
to the details that really matter. Typically, fiberglass —
selected as the least expensive option up front — is jammed
in the walls and stuffed around electrical wires, plumbing pipes,
and HVAC ducts, then covered up as soon as the municipality allows.
The result is gaps, compression, and hollow voids that compromise
occupant comfort and increase the building's energy loads. A sloppy
insulation job can also lead to moisture problems by creating
thermal conditions in walls and ceilings that promote condensation,
wetting, mold growth, and rot.
Batt insulation works best when it is fully lofted, not jammed
into the tight spaces (above). Compression of the batt reduces the
number of air pockets that provide the material's insulation value.
It also leaves a hollow between the insulation and the drywall,
creating areas where air can circulate. These voids can siphon off
energy and may create conditions for condensation and moisture
problems.
Bright Star
The updated Energy Star label for homes provides a quality standard
that can guide builders away from these problems. New program
requirements have raised the level of quality in the program,
making it a label that savvy home buyers will more likely be
looking for. As of January 1, 2007, a home that qualifies for an
Energy Star label must pass a "thermal bypass inspection": a
rigorous assessment of a home's air barrier. The bypass inspection
requires builders to follow the EPA's Thermal Bypass Inspection
Checklist — a 25-point list of details aimed at stopping the
movement of heat around or through the insulation. Thermal bypasses
— the defects that most commonly reduce the energy
performance and comfort of homes — typically result from
missing or compressed insulation, missing air barriers, and gaps
between the air barrier and the insulation.
The Energy Star Thermal Bypass Inspection Checklist must be
completed by a certified home energy rater. However, in order for a
home to qualify for the Energy Star label, up to six items may be
verified by the builder to minimize required field trips by the
rater.
In my opinion, this checklist is one of the best guidelines to come
out of the EPA's Energy Star program, and I think it substantially
raises the bar for thermal and moisture performance of building
envelopes. Of particular value to builders, the 86-page Thermal
Bypass Checklist Guide (available free online at www.energystar.gov;
search "Thermal Bypass Guide") provides a very practical and
comprehensive look at reducing air infiltration. It should be
required reading for anyone who's serious about building a quality
home in any climate, but especially in demanding coastal
climes.
The issues are easily solved with ccSPF, which sticks to the bottom
of the subfloor so insulation and air barrier are always in
contact. The foam also stops air infiltration. It is a good idea to
wrap any plumbing with a thin layer of fiberglass insulation before
spraying foam over it to make servicing the plumbing easier.
An Insulation for All Reasons
I've included in this article a short catalog of some of the
problem areas addressed on the Thermal Bypass Inspection Checklist
that I find are frequently missed.
What stands out about all of these problem points is that they can
be difficult to get right with inexpensive fiberglass insulation
unless a builder is working with an experienced and service-minded
insulation crew. However, these problems are easily avoided when
using closed-cell spray foam (ccSPF) insulation. This alone
provides a strong argument for always using ccSPF, but it's
certainly not the only reason.
There are many reasons why ccSPF makes particularly good sense in a
coastal home:
• It has a high R-value of 6.5 to 7 per inch.
• It absorbs a negligible amount of water. It can even be used
as an effective secondary rain barrier and is the only
FEMA-approved insulation for flood-resistant construction.
• It does a good job of controlling diffusion.
• It has good air barrier qualities to reduce airflow into and
out of wall cavities.
• It expands to fill voids in hard-to-
insulate areas.
• It provides some structural integrity to the frame (see "The
Structural Properties of Foam," page 26).
Steve Easleyis principal of Steve Easley
Associates, a company based in Danville, Calif., that provides
building-science training and quality assurance for builders
nationwide. All photos by the author.