Normally I don't get too excited about insulation. I don't suppose you do
either. But it's a key factor in making a structure into a complete
and comfortable energy-efficient home. Properly installed, insulation
with the R-value required by the building code helps keep a home warm
in the winter and cool in the summer. Of course, that helps keep those
utility bills down. Perhaps that's why some customers do get excited
What about housewrap? Does it increase the R-value? Is it better than
the 15-pound felt that we're all used to? Building paper helped make
a structure weathered-in (waterproof from wind-driven rain) before the
siding was installed. It also increased the effectiveness of the insulation
and reduced drafts from the outside. Air infiltration and moisture buildup
are major problems common to many homes, especially older ones.
Today, modern housewraps act as a weather barrier, yet they're permeable
to release moisture vapor trapped within wall cavities. These materials
actually allow a home to breathe, letting moisture vapor escape before
it leads to condensation and eventually mildew and rot. Housewrap still
stops penetration by wind-driven rain, as well as air or wind penetration
through seams, cracks, or directly through a wall cavity. Temperature
changes within the walls mean more energy to heat homes because the
walls are lower in temperature. And in warm climates (or during summer),
warm air moving inside a wall cavity means that more energy is required
to cool the house.
To create a high-performance insulating system, first apply caulk
or foam sealant to fill all seams, cracks, openings around the top of
the foundation, and around any water or electrical lines that pass through
exterior walls, floor, and ceiling areas. Then install the insulation.
This creates a tighter building envelope and prevents air and wind penetration.
It may cut down air infiltration by 50 percent compared to homes where
these sealants haven't been applied.