In the chilly months of winter, cold air tries to come through the cracks of your house and push out the warm air inside. This process is called infiltration. From 15-35% of winter heat loss is caused by infiltration of cold air into a "leaky house". The majority of these cracks are around windows and doors. A 1/16 inch crack around a doorframe is equal to a hole the size of your fist, and the effect of all such leaks in even a well insulated house is about the same as if you left a double-hung window open all winter. Sealing those cracks can result in big savings on your heating bills.
To test for infiltration, choose a cold windy day. Move your hand around the edges of doors and windows. If you feel a draft, you know the original caulking or weather stripping is no longer doing its job. Even in a relatively new house, if the building contractor used an oil or resin caulk, it may have pulled loose in as little as one year, depending on the expansion and contraction caused by weather extremes. It doesn't take a professional to replace caulking or weather stripping because it is easy enough to do it yourself.
CAULKING
Caulking is required wherever two different materials or parts of the house meet, such as around outside doorframes, windows, foundation sills, and electrical boxes. Acrylic latex caulk is the best general-purpose type of caulk and is excellent for plugging gaps in wood, plaster, and drywall. It sticks to damp surfaces, can be cleaned up with water and should last up to ten years. The more durable, flexible and costly silicone or polysulfide caulk is a clear, colorless caulk which cannot be painted but is nearly invisible in a seam. It should be used where there is movement between two surfaces because of stress (eg. a slamming door). Caulking compound also comes in rope form (Simply, unwind it and force it into cracks with your fingers).
To apply the standard caulking you will need an inexpensive caulking gun, caulk in cartridges, filler materials, a putty knife or large screwdriver, and a ladder. The number of cartridges required will vary with the size of the house and number and size of cracks to be filled. Two windows or doors can usually be caulked with one cartridge. Caulking should not be applied in very cold weather. Make sure the outside temperature is warmer than 40 F.
Before applying caulking compound, clean the surface of paint build up, dirt, or deteriorated caulk with a putty knife or large screwdriver. On bare wood, caulking compound adheres better if the surfaces are primed with linseed oil or paint. Cut the tip on the caulking cartridge straight across, break the inner seal and inset cartridge into the caulking gun. Hold the caulking gun at a 45-degree angle and move along the crack as you squeeze out a bead of compound. Force the caulking compound into the crack or opening deeply enough so that you are certain it adheres completely to both sides for a tight seal. Smooth the surface either by hand or with a putty knife. On extra wide cracks like those at the sills (where the house meets the foundation), first fill with fiberglass insulation strips or other insulating material. Then finish the job with caulk.
WEATHER STRIPPING
Do not use caulk in a moving joint around a door hinge or where a window slides open. This require some kind of weather stripping material. There are several common types of weather stripping that can be installed with a minimum of tools and skills.
FOR WINDOWS AND DOORS:
Thin spring metal weather strips. These are hardly visible when installed and are extremely durable and long lasting. They are cut to length with tin snips and tacked in place. Lift the outer edge of the strip with a screwdriver after tacking for a better seal.
Rolled vinyl weather strips. Durable and easy to cut with tin snips, they are nailed against door and window casings,
Adhesive backed foam tape. Hardly visible after installation but not very durable. It is most effective on doors. It may be applied on window frames where there is no friction.
FOR DOORS ONLY:
Sweeps. Useful for flat thresholds, although they may drag on a carpet or rug. Cut the sweep to fit 1/16 of an inch from the edges of the door. Some sweeps are installed inside and some on the outside.
Door Shoes. These are good for wood thresholds that are not worn. The door must be removed and then trimmed along the bottom to allow sufficient clearance. Cut the door to width. Install by sliding vinyl and fastening with screws.
Vinyl bulb thresholds. If there is no threshold, or the wood is worn, use vinyl bulbs. The vinyl will eventually wear out, but replacements are available. Remove the door: trim the bottom. Make a 1/8-inch bevel to seal the vinyl, cutting in the right direction for opening.
INSTALLATION TIP: For best results, properly weather stripped doors and windows should fit flush against the stripping when closed.
Special thanks to the New Mexico Energy and Natural Resources Department for their contribution to this article.
