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How to Make Old Windows More Energy-Efficient (page 1 of 2)

Learn how to complete a variety of window maintenance projects, including replacing wooden beads, installing double-glazed units and removing broken glass.

Excerpted from Do It Yourself Home Improvement

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Window maintenance is an often overlooked part of home improvement. Replacing older windows with energy efficient windows is a popular DIY project. But not all older windows need to be replaced when you encounter problems, and some historic districts have very strict guidelines. Some windows may need glass replaced, paint removed, caulk to seal the air leaks or ropes replaced. Older windows are hung on ropes and need to be properly balanced to open and close properly. If you have older windows, you may want to invest time and money in restoring them. Newer windows may be more difficult to update and repair, as they often available only as units.

Using Putty

Clean the rabbet before you start. Cut some putty from its container with a putty knife. If it is particularly sticky, spread a small amount of powder filler on your hands, and coat the putty itself with more filler to make it easier to handle. Work it in the palms of your hands so that you achieve a malleable, smooth consistency before you begin.

Work from the outside. Roll the putty into strips about 3/8 inch in diameter. Press the strips into the rabbet (Image 1).

Maneuver the glass into the rabbet. Press gently around the edges of the pane (Image 2).

Hammer glazing pins into the rabbet, not quite touching the glass. Their heads will be hidden by the finished putty. Use cardboard to protect the glass (Image 3).

Press more strips of putty into the junction created by the glass and the rabbet using your thumb (Image 4).

Use a putty knife to trim excess putty from behind the glass, then draw the knife along the external putty to create a smooth seal. Miter the corners neatly (Image 5).

Remove smears from the glass with mineral spirit. Before painting, let the putty dry until a hard skin has formed on its surface (Image 6).

View photo gallery instructions for this project

Replacing Wooden Beads

Wooden glazing beads are attached to the exterior of the frame to secure panes of glass. They can be used to glaze a window that was previously puttied. A snug fit is essential to ensure that the glass is secure and weatherproof. Glazing silicone is used to seal the joint.

Apply window caulk around the rabbet to one-third of its depth. Press the pane gently into position to create a seal (Image 1).

Nail each bead in place on the silicone, using at least two glazing pins for each bead. The inner edge of each bead should sit flush against the glass. Wipe off any excess silicone (Image 2).

Installing Double-Glazed Units

Double-glazed windows have two layers of glass separated by air space, which creates nearly twice the insulation as single glazed units. Glass does not provide insulation value. It is the air between the layers of glass that creates the insulation of an air pocket. Some types of double-glazed windows also use a plastic film as an inner glazing layer. While you can achieve a similar result with a storm window, it is not as effective as there is heat loss along the frame of the storm window.

If you add a third or fourth layer of glass, the insulation value of your window will increase. Each layer of glass traps some of the heat that passes through, increasing the window’s resistance to heat loss. When double glazing windows are manufactured, the air between the glass is dried and then the space is sealed airtight. This eliminates possible condensation problems later. Some double-glazed windows are made with a reflective coating, which helps the insulation value.

Place two packers along the bottom of the glazing rabbet. Vinyl glazing systems vary, so follow guidelines specific to your system. Further packers may be required around the edge of the unit to ensure that it is positioned centrally and securely within the frame (Image 1).

Position the unit on the packers and push it into the rabbet. Take care not to crease the waterproof seal or gasket as you push (Image 2).

Clip the glazing beads and gaskets into position to hold the unit securely (Image 3).

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Excerpted from Do It Yourself Home Improvement

© Dorling Kindersley Limited 2009

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