Caulking and Weatherstripping


Caulk forms a flexible seal for cracks, gaps, or joints less than 1-quarter-inch wide. You can use a caulking compound to seal air leaks in a variety of places throughout your home, including around windows and door frames.

In addition to sealing air leaks, caulking can also prevent water damage inside and outside of the home when applied around faucets, ceiling fixtures, water pipes, drains, bathtubs and other plumbing fixtures.


Most caulking compounds come in disposable cartridges that fit in half-barrel caulking guns (if possible, purchase one with an automatic release). Some pressurized cartridges do not require caulking guns. When deciding how much caulking to purchase, consider that you'll probably need a half-cartridge per window or door and four cartridges for the foundation sill. Caulking compounds can also be found in aerosol cans, squeeze tubes, and ropes for small jobs or special applications.

Caulking compounds vary in strength, properties, and prices. Water-based caulk can be cleaned with water, while solvent-based compounds require a solvent for cleanup. Table 1 provides information about the types of common caulking compounds.

Table 1: Common Caulking Compounds
Caulking Compound Recommended Uses Cleanup Shrinkage Adhesion Cost Comments
Silicone: Household Seals joints between bath and kitchen fixtures and tile. Forms adhesive for tiles and metal fixtures. Seals metal joints as in plumbing and gutters. Dry cloth if immediate; mineral spirits or naphtha. Little or none. Good to excellent. High Flexible: cured silicone allows stretch of joints up to three times normal width or compression to one-half the width.
Silicone: Construction Seals most dissimilar building materials such as wood and stone, metal flashing, and brick. Dry cloth if immediate; mineral spirits or naphtha. Little or none. Good to excellent. High Permits joints to stretch or compress. Silicones will stick to painted surfaces, but paint will not adhere to most cured silicones.
Polyurethane, expandable spray foam Expands when curing; good for larger cracks indoors or outdoors. Use in nonfriction areas, as rubber becomes dry and powdery over time. Solvent such as lacquer thinner, if immediate. None; expands quite a bit. Good to excellent. Moderate to high. Spray-foam quickly expands to fit larger, irregular-shaped gaps. Flexible. Can be applied at variable temperatures. Must be painted for exterior use to protect from ultraviolet radiation. Manufacturing process produces greenhouse gases.
Water-based foam sealant Around window and door frames in new construction; smaller cracks. Water. None; expands only 25%. Good to excellent. High. Takes 24 hours to cure. Cures to soft consistency. Water-based foam production does not produce greenhouse gases. Will not over-expand to bend windows (new construction). Must be exposed to air to dry. Not useful for larger gaps, as curing becomes difficult.
Butyl rubber Seals most dissimilar materials (glass, metal, plastic, wood, and concrete.) Seals around windows and flashing, bonds loose shingles. Mineral spirits or naphtha. From 5% to 30%. Good. Moderate to high. Durable 10 or more years; resilient, not brittle. Can be painted after one week curing. Variable shrinkage; may require two applications. Does not adhere well to painted surfaces. Toxic; follow label precautions.
Latex Seals joints around tub and shower. Fills cracks in tile, plaster, glass, and plastic; fills nail holes. Water. From 5% to 10%. Good to excellent. Moderate. Easy to use. Seams can be trimmed or smoothed with moist finger or tool. Water resistant when dry. Can be sanded and painted. Less elastic than above materials. Varied durability, 2–10 years. Will not adhere to metal. Little flexibility once cured. Needs to be painted when used on exteriors.
Oil or resin-based Seals exterior seams and joints on building materials. Mineral spirits or naphtha. From 10% to 20%. Good. Low. Readily available. Least expensive of the four types. Rope and tube form available. Oils dry out and cause material to harden and fall out. Low durability, 1–4 years. Poor adhesion to porous surfaces like masonry. Should be painted. Can be toxic (check label). Limited temperature range.


Although not a high-tech operation, caulking can be tricky. Read and follow the instructions on the compound cartridge. Save yourself some trouble by remembering a few important tips:

  • For good adhesion, clean all areas to be caulked. Remove any old caulk and paint, using a putty knife or a large screwdriver. Make sure the area is dry so you won't seal in moisture.

  • Apply caulk to all joints in a window frame and the joint between the frame and the wall.

  • Hold the gun at a consistent angle. Forty-five degrees is best for getting deep into the crack. You know you've got the right angle when the caulk is immediately forced into the crack as it comes out of the tube.

  • Caulk in one straight continuous stream, if possible. Avoid stops and starts.

  • Send caulk to the bottom of an opening to avoid bubbles.

  • Make sure the caulk sticks to both sides of a crack or seam.

  • Release the trigger before pulling the gun away to avoid applying too much caulking compound. A caulking gun with an automatic release makes this so much easier.

  • If caulk oozes out of a crack, use a putty knife to push it back in.

  • Don't skimp. If the caulk shrinks, reapply it to form a smooth bead that will seal the crack completely.

Before applying new caulk, remove old caulk or paint residue remaining around a window using a putty knife, stiff brush, or special solvent. After old caulk is removed, new caulk can then be applied to all joints in the window frame and the joint between the frame and the wall. The best time to apply caulk is during dry weather when the outdoor temperature is above 45°F (7.2°C). Low humidity is important during application to prevent cracks from swelling with moisture. Warm temperatures are also necessary so the caulk will set properly and adhere to the surface.


You can use weatherstripping in your home to seal air leaks around movable joints, such as windows or doors.

To determine how much weatherstripping you will need, add the perimeters of all windows and doors to be weatherstripped, then add 5%–10% to accommodate any waste. Also consider that weatherstripping comes in varying depths and widths.


Choose a type of weatherstripping that will withstand the friction, weather, temperature changes, and wear and tear associated with its location. For example, when applied to a door bottom or threshold, weatherstripping could drag on carpet or erode as a result of foot traffic. Weatherstripping in a window sash must accommodate the sliding of panes—up and down, sideways, or out. The weatherstripping you choose should seal well when the door or window is closed while allowing it to open freely.

Choose a product for each specific location. Felt and open-cell foams tend to be inexpensive, susceptible to weather, visible, and inefficient at blocking airflow. However, the ease of applying these materials may make them valuable in low-traffic areas. Vinyl, which is slightly more expensive, holds up well and resists moisture. Metals (bronze, copper, stainless steel, and aluminum) last for years and are affordable. Metal weatherstripping can also provide a nice touch to older homes where vinyl might seem out of place.

You can use more than one type of weatherstripping to seal an irregularly shaped space. Also take durability into account when comparing costs. Table 1 below contains information about the common types of weatherstripping.

Table 1: Common Weatherstripping
Weatherstripping Best Uses Cost Advantages Disadvantages
Tension seal:
Self-stick plastic (vinyl) folded along length in a V-shape or a springy bronze strip (also copper, aluminum, and stainless steel) shaped to bridge a gap. The shape of the material creates a seal by pressing against the sides of a crack to block drafts.
Inside the track of a double-hung or sliding window, top and sides of door. Moderate; varies with material used. Durable. Invisible when in place. Very effective. Vinyl is fairly easy to install. Look of bronze works well for older homes. Surfaces must be flat and smooth for vinyl. Can be difficult to install, as corners must be snug. Bronze must be nailed in place (every three inches or so) so as not to bend or wrinkle. Can increase resistance in opening/closing doors or windows. Self-adhesive vinyl available. Some manufacturers include extra strip for door striker plate.
Plain or reinforced with a flexible metal strip; sold in rolls. Must be stapled, glued, or tacked into place. Seals best if staples are parallel to length of the strip.
Around a door or window (reinforced felt); fitted into a door jamb so the door presses against it. Low Easy to install, inexpensive. Low durability; least effective preventing airflow. Do not use where exposed to moisture or where there is friction or abrasion. All-wool felt is more durable and more expensive. Very visible.
Reinforced foam:
Closed-cell foam attached to wood or metal strips.
Door or window stops; bottom or top of window sash; bottom of door. Moderately low Closed-cell foam an effective sealer; scored well in wind tests. Rigid. Can be difficult to install; must be sawed, nailed, and painted. Very visible. Manufacturing process produces greenhouse gas emissions.
Nonporous, closed-cell foam, open-cell foam, or EDPM (Ethylene Propylene Diene Monomer) rubber.
Top and bottom of window sash; door frames; attic hatches and inoperable windows. Good for blocking corners and irregular cracks. Low. Extremely easy to install. Works well when compressed. Inexpensive. Can be reinforced with staples. Durability varies with material used, but not especially high for all; use where little wear is expected; visible.
Rolled or reinforced vinyl:
Pliable or rigid strip gasket (attached to wood or metal strips.)
Door or window stops; top or bottom of window sash; bottom of a door (rigid strip only). Low to moderate. Easy installation. Low to moderate cost. Self-adhesive on pliable vinyl may not adhere to metal; some types of rigid strip gaskets provide slot holes to adjust height, increasing durability. Comes in varying colors to help with visibility. Visible.
Door sweep:
Aluminum or stainless steel with brush of plastic, vinyl, sponge, or felt.
Bottom of interior side of in-swinging door; bottom of exterior side of exterior-swinging door. Moderate to high. Relatively easy to install; many types are adjustable for uneven threshold. Automatically retracting seeps also available, which reduce drag on carpet and increase durability. Visible. Can drag on carpet. Automatic sweeps are more expensive and can require a small pause once door is unlatched before retracting.
Works similarly to refrigerator gaskets.
Top and sides of doors, double-hung and sliding window channels. High Very effective air sealer.  
Tubular rubber and vinyl:
Vinyl or sponge rubber tubes with a flange along length to staple or tack into place. Door or window presses against them to form a seal.
Around a door. Moderate to high. Effective air barrier. Self-stick versions challenging to install.
Reinforced silicone:
Tubular gasket attached to a metal strip that resembles reinforced tubular vinyl
On a doorjamb or a window stop. Moderate to high. Seals well. Installation can be tricky. Hacksaw required to cut metal; butting corners pose a challenge.
Door shoe:
Aluminum face attachment with vinyl C-shaped insert to protect under the door.
To seal space beneath door. Moderate to high. On the exterior, product sheds rain. Durable. Can be used with uneven opening. Some door shoes have replaceable vinyl inserts. Fairly expensive; installation moderately difficult. Door bottom planning possibly required.
Bulb threshold:
Vinyl and aluminum
Door thresholds Moderate to high. Combination threshold and weatherstrip; available in different heights. Wears from foot traffic; relatively expensive.
"Frost-brake" threshold:
Aluminum or other metal on exterior, wood on interior, with door-bottom seam and vinyl threshold replacement.
To seal beneath a door. Moderate to high. The use of different materials means less cold transfer. Effective. Moderately difficult to install, involves threshold replacement.
Fin seal:
Pile weatherstrip with plastic Mylar fin centered in pile.
For aluminum sliding windows and sliding glass doors. Moderate to high. Very durable. Can be difficult to install.
Interlocking metal channels:
Enables sash to engage one another when closed
Around door perimeters. High. Exceptional weather seal. Very difficult to install as alignment is critical. To be installed by a professional only.


Weatherstripping supplies and techniques range from simple to the technical. Consult the instructions on the weatherstripping package. Here are a few basic guidelines:

  • Weatherstripping should be applied to clean, dry surfaces in temperatures above 20°F (-7° C).
  • Measure the area to be weatherstripped twice before you cut anything.
  • Apply weatherstripping snugly against both surfaces. The material should compress when the window or door is shut.

When weatherstripping doors:

  • Choose the appropriate door sweeps and thresholds for the bottom of the doors.
  • Weatherstrip the entire door jamb.
  • Apply one continuous strip along each side.
  • Make sure the weatherstripping meets tightly at the corners.
  • Use a thickness that causes the weatherstripping to tightly press between the door and the door jamb when the door closes, without making it difficult to shut.

For air sealing windows, apply weatherstripping between the sash and the frame. The weatherstripping shouldn't interfere with the operation of the window.

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