Sealing & Weatherization

More about Sealing & Weatherization

Caulking

Caulk is a standard solution to seal cracks, gaps, and joints that are less than ¼’’ wide. Though typically considered with respect to plumbing, caulking can also seal areas around windows and door frames.  The compounds used for caulking are available in varying quantities, strengths, properties, and prices. Proper application is essential for effective sealing, and may be performed with caulking guns (which require disposable cartridges), pressurized cartridges, aerosol cans, squeeze tubes, or pre-fabricated ropes.

Regardless of type, here are some general guidelines to maximize the lifespan and effectiveness of your caulking:

1. Make sure the target area is both clean and dry before you begin
2. When caulking around window frames, apply the caulk to both the window frame joints and the seam between the wall and the frame.
3. Maintain a consistent angle with the gun (or tube) when applying. The caulk should immediately fill the crack upon application. Make sure that the caulk adheres to both sides of the seam to ensure an effective seal.
4. Try to be as smooth as possible when applying the caulk. Stopping and starting will create ridges in the caulking. If extra caulking oozes beyond the seam, use a putty knife to push it back into place.
5. Try and do your sealing on a dry day when the temperature is above 45°F. This will allow the caulk to set and stick to the surfaces.

The caulking most appropriate for retrofitting and air sealing is described below:

1. Silicone construction ($$$): This type of caulking is excellent for creating a seal between different types of materials, such as brick and wood. It hardly shrinks and is very adhesive. Additionally, it allows the sealed joints to stretch and compress.
2. Polyurethane, expandable spray foam ($$-$$$): This type of caulking expands upon application and can be applied at a wide range of temperatures, making it excellent for sealing large cracks, both indoors and outdoors. It can become powdery over time, a therefore should be used in areas that will not be subject to frequent contact.
3. Butyl rubber ($$-$$$): Butyl rubber is also good at creating a seal between different materials, though it does not adhere well to already-painted surfaces. With proper application, it can last for ten or more years without becoming brittle. Caution: this caulking is toxic—observe packaging instructions!
4. Oil or resin-based ($): This least-expensive option is often used for sealing exterior seams and joints. It tends to dry out after 1-4 years, making it the least durable. Additionally, it does not adhere well to porous surfaces and is only useful in a limited temperature range. It too can be toxic.

Weatherstripping

Weatherstripping can be used in conjunction with caulking to provide a relatively inexpensive solution for air leakage. It is intended for use around movable joints, such as windows or doors. In deciding on the proper type, consider the particular area and its level of use and exposure to weather and temperature. Also, the material (felt, vinyl, or metal) should be contrasted for durability, ease of application, and price.

When applying weatherstripping, remember these tips:

1. Make sure that the stripping is measured correctly and is placed to meet snugly in the corners.
2. As with caulking, make sure that the stripping is applied to clean, dry surfaces at temperatures above 20°F.
3. The thickness of the weatherstripping should allow the door or window to close easily, but also compress upon closure.
4. Do not use pieces of stripping. Apply one continuous strip to each side of a seal.

The weatherstripping most appropriate for retrofitting and air sealing is described below:

1. Tension-seal: This type of weatherstripping is usually either self-stick vinyl or a metal strip that is folded in half length-wise to form a bridge over a gap. They are generally placed inside of the track of a double-hung or sliding window, or along the sides and top of a door. The durability, invisibility, and ease of installation (especially of the vinyl style) make these strips a popular choice. The metal varieties must be nailed into place. Both styles can make opening or closing the door or window slightly more difficult.
2. Felt: Felt is easy to install and inexpensive, but it also the least durable and effective. It must be applied with staples, glue, or tacks, and is generally very visible. It should not be used in areas exposed to moisture or friction.
3. Reinforced foam: This foam is reinforced with metal or wood strips, providing a rigidity that is useful for stopping wind. It must be sawed, nailed, and painted before being used door and window stops, for the bottom of a door, or the top of a window. It is relatively inexpensive.
4. Tape: Non-porous, closed-cell, or open cell foam, as well as EDPM rubber can be applied to the top and bottom of window sashes, to attic hatches and unused windows.  These varieties of tape are very easy to install and are inexpensive. Tape is a good solution for low-use areas, as its durability is not particularly high and it is visible.
5. Rolled or reinforced vinyl: Like reinforced foam, reinforced vinyl is relatively inexpensive, easy to install, and visible (though it comes in varying colors). It can be used in door or window stops, on the top or bottom of a window sash, or attached to the bottom of a door.
6. Door sweep: Door sweeps are comprised of a metal strip attached to a brush of vinyl, sponge, or felt and hung on the bottom of a swinging door. They are available in many different styles and are relatively easy to install. High visibility and potentially damaging effects on carpet reduce their appeal, though automatically-retracting sweeps are now available.
7. Magnetic: These relatively expensive air sealers work with technology akin to that of your refrigerator. They are extremely effective on the top and sides of doors and in double-hung and sliding windows.
8. Tubular rubber and vinyl: These tubes are staples or tacked into place around a door to form a seal. The self-sticking types are sometimes difficult to install and the price can range from moderate to expensive.
9. Reinforced silicone: These tubular gaskets can be applied to a doorjamb or window stop to form a good seal. They are also moderately expensive and sometimes difficult to install due to the metal reinforcement.
10. Door shoe: Door shoes are used to seal the space beneath a door. They are relatively durable and shed water on the door’s exterior. Relatively expensive, their installation can also be somewhat difficult.
11. Bulb threshold: These combination threshold and weatherstrips are relatively expensive and can wear out with repeated foot traffic. They are available in both vinyl and aluminum and in different heights, making them very versatile.
12. “Frost-brake” threshold: This effective solution utilizes metal on the exterior of the door, wood on the interior, and replaces the door-seam to fit a vinyl threshold. They are sometimes difficult to install because of the replacement of the threshold, and are moderately expensive.
13. Fin seal: These pile weatherstrips with a Mylar fin can be challenging to install but are very durable for sliding windows and glass doors.
14. Interlocking metal channels: These excellent door seals must be installed by a professional, and thus are expensive. However, they very effectively block air and are invisible when installed.