Weatherstripping
Weatherstripping
which blocks drafts around doors and windows won't save much energy. Recent
studies have shown that such drafts actually contribute little to overall
heat loss. Still, weatherstripping will do a lot to make the house feel more comfortable. That may save some energy indirectly, since you may
not need to turn up the thermostat as much if the room isn't drafty.
Weatherstripping
comes in a wide variety of designs and materials: foam or rubber tapes,
plain or reinforced with a strip of wood; a tubular plastic gasket, plain
or reinforced; felt, plain or reinforced; and springy strips of plastic
or metal. You should buy weatherstripping by type, not by brand. It should
be easy to cut and form to the proper size and shape, and easy to secure
to a flat surface. It should be resilient enough to seal even after it's
been crushed or rubbed thousands of times. It must be able to survive
extremes of heat, cold, and humidity. It also should interfere as little
as possible with the movement of a door or window.
Air leakage
This is a key test;
the ability to impede airflow in the equivalent of a 50-mph wind. Two
types work well--closed-cell foam with rubber tapes, and strips with a
tight-sealing, rigid gasket. Reinforced felt and open-cell foam tape are
much less effective. Inch for inch, reinforced felt allows more than 250
times as much air to leak through as closed-cell foam.
Aging
Most types of stripping
held up well enough through 600 hours of test. Plastic and bronze tension
seals, felts, and silicone gaskets hold up well. The worst, open-cell
foam tape, becomes dry, brittle, and powdery. Whatever material it is
made of, weatherstripping works by plugging and sealing a gap between
moving surfaces. Some types work well on both doors and windows, while
others are more limited. Here is a rundown on the types you'll see in
the stores:
Tape - EPDM (ethylene-propylenediene monomer) rubber, non-porous, closed-cell
foam, open-cell foam, and sponge rubber. You can buy rolls of tape in
various widths and thicknesses. The tape is self-adhesive and thus extremely
easy to install. The tape is cut to length with scissors; the backing
peeled away and stuck in place.
Best uses: Along
a doorjamb or at the top and bottom of a window sash. It is not well suited
for a window jamb, although some manufacturers' literature list this usage.
Tape's size and flexibility make it well suited for blocking an irregular
crack. Tape that is rectangular in cross-section is well suited for sealing
corners. Tape works best when it is compressed.
Reinforced
foam - Closed-cell foam tape attached to a strip of wood
molding.
Best uses: Nailed
in place around a window or doorjamb. Reinforced foam can be a bother
to install because it must be sawed, nailed, and painted.
Tension
seal - A self-stick strip of plastic that is folded along
its length to form a V, or a springy bronze strip that is shaped to bridge
the gap between, for example, a window sash and its frame. The shape of
the material creates a seal by pressing against the sides of a crack to
block drafts.
Best uses: Inside
the track of a double-hung window or between a door and its jamb. Plastic
V strips are easier to install than bronze; the latter must be nailed
and formed in place. Either type of tension seal can be difficult to install
in a corner since the strips must be mitered so they will join tightly.
One variant design we encountered, which combined a V-shaped gasket of
vinyl-clad foam and wood reinforcement, sealed well enough but was fairly
difficult to install.
Felt. - Plain or reinforced with a flexible metal strip; sold in rolls that
must be cut to length and stapled or tacked into place. Felt seals best
if the staples are positioned parallel to the length of the strip.
Best uses: Plain
felt can be fitted in a doorjamb so that the door presses against it.
Reinforced felt can seal around a door or a window.
Pile - A narrow strip of furry, carpetlike material with a rigid back. Some
versions come with an adhesive backing.
Best uses: Fitted
in recessed slots around the perimeter of a window sash, storm door, or
sliding glass patio door.
Tubular
rubber and vinyl - Tubes of sponge rubber or vinyl with
a flange along their length that is stapled or tacked into place. These
gaskets work when a door or window presses against them to form a seal.
They are not as easy to install as self-stick types.
Best uses: Around
a door.
Reinforced
silicone - A tubular gasket attached to a metal strip
similar in appearance to reinforced tubular vinyl. It seals well, but
it can be hard to install. You must hacksaw the metal strip to size. Also,
butting two pieces tightly in a corner can be tricky. (This product may
be easier to find in a contractors' supply store than in a hardware store.)
Best uses: On a doorjamb
or window stop.
Door
seals - Vinyl door seals with multiple sealing edges
of equal length are better than felt and brush seals.
Best uses: To seal
the space beneath a door.
Recommedations
No single type of
weatherstripping works well everywhere. You will probably need one type
for doors, another for windows. The descriptions on the preceding pages
can help you decide which type is best to use for each specific purpose.
Product packaging also gives recommendations for use.
Self-stick tapes
probably have the widest range of uses. They are also the easiest type
to install and provide the best seal. However, they do not last very long.
To block drafts around double-hung windows, use a plastic V-strip or a
bronze tension seal in the space between the window sash and the frame.
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