Michigan
State University Extension
Home Maintenance And Repair
06/24/03
Energy Tips - Weatherstripping
Insulation
is not the whole story for energy conservation! Even if your home is
well insulated, energy may be wasted through air infiltration. Air can
leak around doors and windows, foundations, chimneys, and exterior
plumbing. In the winter, air heated by your furnace is lost to the
outside; in summer, hot outdoor air puts an extra load on your air
conditioner. If your home is typical, one-half to three-quarters of
your fuel bill is the result of air infiltration. Weatherizing your
home by caulking and weatherstripping can effectively reduce energy
waste. In fact, the cost of caulking and weatherstripping can usually
be paid back in energy savings in less than one year. This makes
weatherizing one of your best investments in energy conservation. Even
better, it is something that you, the homeowner, can do. Caulking seals
cracks and joints in the house. Weatherstripping reduces air
infiltration around moving parts of the house such as doors and windows
and it has the added benefit of helping to stop dust, dirt, and insects
from entering the house.
There are many types of weatherstripping on the market, each designed
for a different type of application.
Some factors to consider are:
• Resistance to wear by abrasion or friction. For example, the
bottom of a door will receive more wear than the bottom of a window
sash.
• Exposure to weather. Some types of weatherstripping will deteriorate
when exposed to moisture and are best for interior use.
• Material to be weatherstripped. Will a self-adhesive weatherstripping
work, or must it be nailed in place?
• The size of the gap. Some types of weatherstripping are not
suitable for large gaps.
• Evenness of the gap. Will you need a type of weatherstripping that
will adapt to uneven gaps?
• Appearance. Some types of weatherstripping are hidden after
installation; other types may look "added on.''
• Durability. A more expensive type of weatherstripping that will last
can be the most economical choice.
• Ease of installation. Are special tools required?
Buying and Installing Weatherstripping
Weatherstripping is sold by the linear foot. Measure around the
door or window to be weatherstripped to determine the total length
needed. It is also advisable to measure the width and depth of the gap.
Some types of weatherstripping come in different widths and thickness.
If the weatherstripping is too thick, it may interfere with the latch
or locking mechanism on the door or window. If it is too narrow, it
will not be effective. Most weatherstripping is easy to install.
Self-adhesive weatherstripping requires a clean, dry surface. Other
types are held in place by tacks, nails, or screws. These fasteners are
sometimes included with the package of weatherstripping. The
weatherstripping may also have pre-punched holes for easier
application. Some types of weatherstripping are attached to the frame,
while others are attached to the door or window sash. Follow the
manufacturer's directions for the correct location.
Factory-applied weatherstripping on doors is only a recent innovation.
As a result, the exterior doors in thousands of homes throughout the
nation have little or no weatherstripping. Most doors are installed
with a space between the bottom of the door and the floor or threshold.
Sometimes this space can be 1/4 inch or more. If weatherstripping is
not used, this crack allows large amounts of air to flow in and
out of the house.This is known as infiltration.
On a typical 36-inch entry door, this small crack equals a
9-square-inch hole through a wall of your home. To put things in
perspective, this is approximately equal in size to a standard duplex
receptacle or the familiar switch plate.
Door bottom weatherstripping
Several types of door bottom weatherstripping are available.
While easy to apply, these products can interfere with door swing and
require a reasonably level threshold beneath the door. Simple hand
tools are all that are required to install these door bottoms. After
cutting to size with a hacksaw or tin snips, the door bottom is surface
mounted to the inside of the door using wood screws normally provided
by the manufacturer.
A fairly new innovation in weatherstripping is the mechanically
operated, "automatic" door bottom. In this model, a vinyl seal is
automatically lowered against the floor when the door is shut. The seal
retracts when the door is opened.
Thresholds
Thresholds are a more attractive method of windproofing the
bottom of a door. While most are very effective at cutting down
infiltration, the average homeowner may find them difficult to install.
A popular threshold is an aluminum model with the flexible vinyl
"bubble." When new, this threshold is effective, but under constant use
the bubble soon collapses leaving a sizable crack beneath the door. In
most cases the vinyl is replaceable provided a dealer selling that
particular model can be located. Though difficult to install, the
combination vinyl door bottom and aluminum threshold is longwearing and
provides effective weatherproofing. Since the vinyl is mounted in an
aluminum extrusion fastened to the door, the aluminum threshold
receives most of the wear. The only disadvantage in that interior frost
may accumulate on the threshold during extremely cold weather.
Windows
The biggest energy-wasters in any home are the windows and doors
(46% of annual heat loss is through and around glazed areas in windows
and doors). The first step to weatherproofing your home is to check the
windows. If you have double-hung wooden casement windows, begin by
looking at the sash lock. Make sure each lock is fastened securely to
the sash (wooden frame around the glass) and is in working order.
Adjust locks so that the upper and lower sash draw together as you
tighten the lock.
When weatherproofing a steel casement window, again, begin with the
lock. Make sure it is tight (if adjustable) and in working order. The
easiest and best method of weatherstripping steel casement windows is
closed-cell pressure sensitive foam tape. Clean the flanges around the
edge of the sash and press on a thin strip of the tape.
A relative of the steel casement window is the metal basement
window. Most newer homes with basements have several of these units (of
either steel or aluminum) that are cast in place when the basement wall
is poured. Though small in size, infiltration and heat loss through
windows of this type can be extreme. Closed-cell pressure-sensitive
foam tape or transparent weatherstripping tape works well as a method
of weatherproofing these windows.
Studies show that tightly fitting storm windows will cut conduction and
infiltration losses by 50%. Selfstoring, double-or triple-track
aluminum storm windows have traditionally been used, but you can use
inexpensive plastic window and door kits with comparable results. These
kits, usually made of thin plastic sheeting, are practical for
temporary use.
To increase the stability of a plastic sheet storm window, substitute
strips of thin plywood, paneling, or even yardsticks for the cardboard
strips usually supplied with the kit.
Cut the plastic a little larger than the actual window size.
Wrap the top edge of the plastic once or twice around the nailing strip
(the plywood, paneling, etc.) and fasten the strip to the top exterior
of the window casing. Next, wrap the plastic around a second nailing
strip, stretch tightly, and nail to the windowsill. Follow the same
procedure for attaching the sheet to each side of the window.
Polyethylene sheeting is difficult to see through. When clarity is
required, you may want to use a clear acetate or vinyl material that is
also on the market. Sometimes it is difficult to install the sheeting
on the outside of the window. In this case, the easiest method is to
secure the plastic to an interior window casing using transparent
weatherstripping tape. Before installing the sheeting, seal the window
joints with tape or rope caulk.
One of the newer items on the market is a plastic storm window unit
designed for installation on the inside of the house. It is cut to
size, made of clear sheet vinyl, and consists of a system of
interlocking plastic side strips (not unlike the plastic freezer bag).
This storm window installs in minutes and is easily removed from the
inside for cleaning or ventilation. This window works particularly well
when used over casement, basement, or jalousie windows.
Storm doors
For aesthetic reasons, many new homes are built with exposed
single- or double-entry doors. While attractive, this practice must be
questioned because of the heat loss or gain. By covering an exterior
door with a storm door, conduction loss and infiltration through that
door can easily be reduced by 50%.
Many people dislike the appearance of the traditional aluminum storm
door. Manufacturers now offer a full-length glass storm door
particularly designed for homes with exposed-entry doors. To be sure,
these doors are potentially hazardous. However, some states now require
tempered safety glazing in such doors, and attractive decals and
appliqués can be attached at eye level to make sure the glass
door is noticed.
Garage doors
Another large source of infiltration can be found around almost
any overhead garage door. A 1/8-inch crack around the average single
garage door yields almost 50 square inches of area - enough to be
concerned about, especially if the garage is attached to the house.
To begin winterizing a garage door, first purchase a "garage door
bottom." Usually available in rubber or vinyl, the bottom is simply cut
to measure and nailed to the bottom edge of the door with
rust-resistant nails. The final step should be the installation of an
overhead garage door weatherstrip kit. One brand uses a vinyl leaf that
fastens into an aluminum frame. Installation requires only a hammer and
hacksaw and is accomplished by nailing the aluminum strip to the face
of the doorstop, allowing the vinyl leaf to "float" against the face of
the garage door.
Tape products
One of the most effective and economical methods of
weatherstripping is pressure-sensitive vinyl foam tape. When
purchasing, look for a closed-cell vinyl; it is a better insulator than
its rival, the open cell, because the tape's pores are adjacent rather
than connected to each other. Neoprene sponge or vinyl foam is more
durable than sponge rubber or polyurethane foam. Pressure-sensitive
sponge rubber is also available. However, due to its rather low
compressibility, this material is not recommended for use as door
weatherstripping. The vinyl foam tape has better insulating,
compressibility, and adhesive characteristics.
When using any form of pressure-sensitive or stickon weatherstripping,
clean surfaces are necessary. Any exterior doorjamb is sure to have a
film of dust that must be removed prior to application of the product.
A cleaning rag dampened with fast drying lacquer thinner or denatured
alcohol will take off this film.
Nail-on products
Spring metal products have long been used to weatherstrip doors
and windows. However, these materials are harder to install and often
not as effective as the closed-cell vinyl tape.
Three types of coiled tubing are most often used for weatherstripping.
Installation is simple, requiring only a hammer, nails, and a pair of
shears or tin snips. For doors, the tubing is pressed against the
closed door and nailed to the face of the doorstop. Other products
similar
to the tubing have a pre-formed body made of white pine and they are
applied in the same manner.
References
Energy Tips - Weatherstripping, Michigan State University Extension
E2794
GH4881, Weatherstripping Doors, University of Missouri Extension
GH4882 - Reprint Home Energy Management: Weatherstripping Your Windows,
University of Missouri Extension
HEG82-158-A Weatherizing Your Home-Weatherstripping, University of
Nebraska Extension
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