Seal up pipe penetrations
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Photo 1: Clean out the old seal
Pry out old putty and caulk from
around the pipes and wires.
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Photo 2: Trim the rubber boot
Cut the rubber plumbing boot to
fit on top of the siding and around
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Photo 3: Mount the boot
Fit the plumbing boot over the
pipes, then glue it to the siding
with 100 percent silicone caulk.
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Photo 4: Foam the inside
After the caulk dries, squirt a
small amount of minimal-expanding
foam into the opening.
Look behind any air conditioner
compressor or heat exchanger and
you'll find at least one large hole
for plumbing and wiring. It's usually bigger
than it needs to be and sometimes
only partially plugged with a large wad of
electrician's putty, making it a good spot
for heat to get out and mice to get in.
Make these holes more weathertight
and less unsightly with a 1-1/2-in. rubber
plumbing boot (available for about $4 in the
roofing section in home centers).
Gently work out the putty (Photo 1) to
avoid damaging the pipes or wiring.
Replace torn or missing pipe insulation.
Using scissors or a razor knife, cut the
roof boot to fit around the hole and to
match the width of the piece of siding
(Photo 2). Cut a slit in the bottom edge
so the plumbing boot will fit around the
Spread silicone on all four sides of the
hole and at the slit at the bottom to
completely seal the edges (Photo 3).
You may need to tape the rubber to the
siding temporarily until the caulk dries.
Let the caulk dry overnight, then partially
fill the boot with foam; seal the
hole from the inside as well. Use minimal-expanding foam to avoid opening
the slit in the rubber boot, and push the
tip several inches in so the foam
expands into the hole instead of out the
top of the boot (Photo 4).