Weatherizing 7 - Weatherstripping Weatherizing 7 - Weatherstripping

Margin of Error: Not applicable

Weatherstripping products are numerous. Some are quite specialized. All are designed to seal some gap or space where energy is leaking away most often around doors and windows. Modern materials and newer designs have resulted in a great number of effective, yet inexpensive, easy-to-install products. Since there are so many choices, I recommend the following for ease of installation and durability. First, however, there are a couple of things to keep in mind when applying weatherstripping to doors and windows. They must be applied to a clean, dry surface and in temperatures above 20 degrees F.


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If your door threshold (or saddle) is badly deteriorated, it may need to be completely removed and replaced before you add any new weatherizing effects to the doorway. A threshold seals the door at the bottom and is most effective when used in conjunction with a door shoe or door sweep gasket.

Wooden thresholds add warmth in appearance as well, but are a bit more costly than aluminum. Bronze and stainless steel are used but are considerably more expensive. Choose your threshold to match your floor. And take great care in measuring for a replacement. Both wood and aluminum are sold in different lengths for standard door widths.

Tip: When they are properly sized and placed, snug-fitting windows can save a significant amount on your heating and cooling bills.

Replacing a Wooden Threshold

1. Check the clearance between the door and the trim pieces (such as the door stop) and remove if necessary.

2. Swing the door open as far as it will go. If necessary, carefully pry the trim loose with a pry bar and a wooden wedge so as not to damage either the trim or the frame.

3. You may need to use a circular saw or chisel to cut through the threshold to remove it from the doorway. Take great care in this step that you don't cause damage to the interior floor and other trim.

4. Measure and cut the new wooden threshold to the proper length so that it will fit snugly.

5. Notch the threshold to fit properly around the stops.

6. After thoroughly cleaning the old material and dirt out of the doorway - this could mean scraping old caulk and even sanding the surface smooth - spread a generous amount of caulk on the bottom. This will assure an airtight seal in that joint between the floor and the threshold.

7. Tap the new threshold gently into place with your hammer.

8. Drill some pilot holes slightly smaller than the finishing nails you will use to secure the threshold. Then nail the threshold into its permanent position.

9. Countersink the nails with a nailset and fill the holes with wood dough. Sand lightly when dry.

10. Apply a stain if you prefer, and a water repellant finish, or two coats of a penetrating sealer.

Aluminum and metal thresholds. This requires the same installation steps as the wooden threshold. The exception would be the use of a hacksaw with a fine-toothed blade to cut it to length and a metal file to smooth out the roughness. Pre-drill the screw holes in the floor to avoid splitting the sill and to ease screw installation.

You may decide on a vinyl gasket-type threshold, called a thermal threshold. Here a convex vinyl ridge across the top of the threshold presses against the bottom of the door for a tight seal against drafts.

Interlocking thresholds. Another type, less often used and recommended in cold climates, is the interlocking threshold. Although very effective when in good condition, the interlocking elements are difficult to install and easily damaged. Special tools are required, and complicated adjustments are frequently necessary.

Half thresholds. You'll find a half threshold necessary where two floors of different height come together. Half saddles are available in metal or can be made by adapting a wooden saddle. You will need to know the difference in floor heights before purchasing this threshold.

Tip : Never paint the tubular or bulb vinyl weatherstripping. Paint stiffens the vinyl and diminishes its sealing ability.

Door Bottom Seals

These products are used to close the gaps between the threshold and the bottom of the door. Usually, removal of the door is not required for door sweeps. You'll find these to be easiest to apply and inexpensive, thus the most popular. Again, measure carefully. These are sized for standard doors also. Look for products that have clear instructions and, if attached by screws, slotted screw holes for periodic adjustment.



The entry door seal is adhesive backed for ease of application. It is applied to the bottom of the interior side of the inward-swinging door.

A storm/entry door seal can be used for both interior and exterior applications and requires a drill and screwdriver for application. First cut it to fit. Remove the liner from the adhesive back and press it against the bottom of the door, positioning it for maximum contact with the floor. Drill pilot holes and secure the seal with screws.

Door Shoes

Door shoes and automatic door bottoms will require removal of the door for application. For effectiveness, durability, and visibility, they rate about the same as the sweeps. If the clearance between door and threshold is between 1/2 and 3/16 of an inch, application should be no problem. If it's less than that, you'll need to trim some off the bottom of the door. If it's more than 1/2", you might as well look for another solution.

Installing the Door Shoe

  1. Measure the door length to determine if the door needs to be trimmed after you install the new threshold. The door shoe should come with instructions specifying proper clearance. Once the shoe is installed, the door must be able to open and close easily, yet still tightly against all the frame elements.
  2. Remove the door and lay it across a couple of sawhorses or on a sturdy worktable.
  3. Clamp a 2" x 4" or other straightedge to the door bottom to act as a cutting guide. Then saw or plane the door as required.
  4. Measure and cut the door shoe to the width of the door so that it clears the doorstops. For this you will need a hacksaw or a jigsaw with a hacksaw blade.
  5. Attach the shoe to the bottom of the door with the screws provided.
  6. Slip the vinyl bulb into place in the shoe and trim it to length with a utility knife.
  7. Finally, rehang the door and check the fit.

Automatic Door Bottoms

Automatic door bottoms work just the way they sound. When the door is closed, they automatically lower and when the door is opened they automatically raise up to clear the carpet or rug. These must be carefully installed so as not to cause too much tension on the spring mechanism.

That about covers the market for threshold treatments. Assess each doorway carefully and plan accordingly. Don't overlook those doors leading to unheated rooms, the basement, or the garage. They can drain off just as much energy as doors to the outside. If you heat your garage, even periodically, it will be worthwhile to install a seal on that door as well. Special sweeps and shoes are made to keep rain out in addition to sealing cold air gaps. If the weatherstripping does not come with its own fasteners, use galvanized shingle nails placed 3 inches apart.

Now let's get on with weatherstripping the gaps around those door and window frames. The best products for door treatments are of the V-seal variety or spring metal. Unlike windows, doors will be opened and closed frequently throughout the changing seasons. They require something sturdy enough to take constant use.

V-Seal

This self-adhesive, sticky-back type of weatherstripping is made of durable plastic. Easy to install as well as inexpensive, it will last a long time. V-seal should be installed in the seams around the door or window frame so that a tight seal is achieved when the door or window is closed.

Door application

  1. Use a steel tape measure to measure the length of your frame on both sides of the door and across the top.
  2. Cut the plastic V-seal to the appropriate length with scissors.
  3. Remove a couple of inches of the paper liner and position it into place at the top of the door frame so that the bottom of the V-shape will point inward toward the house.
  4. As you bring the plastic down, simultaneously pull off the paper backing and press it into place. If you get it slightly out of line, simply pull it back up. The V-seal will adhere again when you press it back into position.
  5. Run the V-seal all the way down to the bottom of the door frame. Do the same on the opposite side of the frame and at the top.
  6. Now fold the plastic strip along its pre-scored center so that the V will protrude into the space you are trying to seal. Do this all the way around the door.
  7. Be sure the door does not fit too tightly on the top or along the hinge side before installing the weatherstripping. You may need to plane and/or sand the surface a bit for a smoother fit.

Spring Metal

Although it is one of the more expensive weatherstripping materials, spring metal blends beautifully with the frame when the door is open and is virtually invisible when the door is closed. This one requires a bit more work to install, using a tack hammer and awl or screwdriver.

Spring Metal on Doors

  1. Spring metal weatherstripping is installed on the doorjamb next to the door stop. Measure along the sides and the top of the door jamb and cut the spring metal to the correct length with tinsnips.
  2. Begin with the hinge side of the doorway, then do the latch side above and below the latch plate. Install the top piece last miter-cutting the corners.
  3. Position the spring metal so that the edge does not quite contact the stop.
  4. Tack each strip at the ends to align it and stretch it flat against the jamb before nailing along its length.
  5. Some manufacturers provide a strip to fit behind the strike plate. You can also trim a piece to fit.
  6. When all the strips have been installed, run an awl or a screwdriver along the outside edge to spring the metal spring into position.

Now that we're ready to weatherstrip the windows, it is best to begin by discussing the different types of windows, in relation to the types of weatherstripping.

Double-Hung Windows

V-seal and spring metal weatherstripping are most effective and durable on this type of window. Manufacturers require different fastening techniques. Some are pressure sensitive; others require tacking. For durability, the spring metal is the best. But the plastic V-types run a very close second.

A double-hung window is probably the most complicated to weatherstrip. But once you've done one, you can handle the others easily.

Application of V-seal or spring metal

  1. As with any weatherstripping job, begin by cleaning the surfaces well of dirt, grease, and loose paint.
  2. Measure from the base of the inner channel to 2 inches above the top rail of the upper sash. Cut four strips to that length for the inner and outer vertical sash channels. Scissors will easily cut the plastic, but you will need tinsnips for the metal.
  3. Lower the top sash and slip the weatherstripping material down into the channel with the point of the 'V' facing toward the house, or the springy part of the metal toward the outside.
  4. Be sure you do not cover the pulleys and that the sash cords or chains can run free. This may require a bit of custom trimming.
  5. Place weatherstrips full length along the top of the upper sash rail and along the bottom of the lower sash rail.
  6. The mid-section of the window calls for some extra care. The strip for the bottom rail of the upper sash goes on the edge toward the lower sash top rail.

Keep in mind, if you are using spring metal, that the nail heads should be slightly countersunk so that they do not catch on the opposite rail when the window is opened.

Casement Windows and Awning Windows

These cannot normally be sealed by placing weatherstripping outside. The adhesive-backed foam weatherstripping works best on the interior frame where the sash makes contact. Self-adhesive foam rubber weatherstripping is easy to install, widely available, and quite inexpensive. Its major drawback is that it wears quickly and cannot be used where friction occurs, such as the sash channel of a double-hung window.

Sliding Windows

Weatherstripping for sliding metal windows is best installed by a professional glazier or weatherstripping contractor, since it is difficult to find anything on the market for home installation. Sliding wood windows are best insulated with V-seal or spring metal, but adhesive-backed foam or bulb vinyl can also be used effectively if you are closing windows down for the winter and do not plan to open them until warm weather returns. The tubular or bulb vinyl type is reusable season after season. This is especially good for sliding glass doors. Once you have cut it to the proper length, simply press the flanged protrusion into the gap to be sealed, either inside or out. Some types require nailing to secure it. Space the nails 4 to 6 inches apart. One thing the packages seldom tell you is that you should never paint the tubular or bulb vinyl weatherstripping. Because it is a highly visible choice, many people attempt to camouflage it with paint. Unfortunately, this stiffens the vinyl and diminishes its sealing ability.

If both sashes move, weatherstrip them as you would for a double-hung window. If only one sash is movable, use spring metal in the channel where the sash closes against the frame and bulb vinyl on the top, bottom, and where the sashes join.

Jalousie Windows

The design of these windows makes them nearly impossible to weatherstrip. A clear vinyl strip installed across the bottom of each pane is a partial solution, but these must be special ordered. I recommend a removable storm window.

Tip: During the winter wrap your window air conditioners in plastic and seal them with duct tape for better insulation.



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