192It’s technically challenging
to increase wall insulation in
older homes, but the results are
usually worth it. That’s because
most walls were not insulated to
any significant level in the first
place. Many walls are hollow,
while others are simply stuffed
with wood shavings, rags or old
newspapers.
When it comes to increasing
wall insulation, you’ve got three
options.- Boost exterior R-values
This makes the most sense when
you’re already planning to replace
exterior siding. The old siding
comes off, rigid insulation sheets
go on the wall sheathing, then new
siding goes over that.
Pros: Very effective insulation
boost when using 5 cm (2 inch)
thick insulation board.
Cons:Only practical when you’re
replacing siding. Also, window
and door frames need to be
extended in a weatherproof way.- Boost interior R-values
This makes sense if you’ve got
ugly interior wall surfaces that
you want to improve with new
drywall. Rigid insulation sheets
go on the interior faces of exterior
walls, then new drywall goes on
top. Longer-than-usual screws
go through the new drywall,
through the foam, through the old
finished wall surface, then into
the underlying wood frame.
Pros: Very effective insulation
boost. No need to create
weatherproof door and window
frame extensions.
Cons: Only practical when
you’re renovating interior walls.
Reduces room size slightly and
Strategy No. 2: Boost wall insulation
HOME & DESIGN: OLD-HOUSE ENERGY UPGRADES