DO-IT-YOURSELF : No Pane, No Gain--It’s Simple to Replace a Broken Window

Replacing a broken window pane is relatively simple. Here’s how to do it:

Double-Hung Windows

* The first step is to remove the damaged glass without cutting yourself. If the pane is only cracked, glue newspaper to both sides of the glass.

When dry, remove the putty and the pane will come out without splintering. Or crisscross the pane on both sides with duct or masking tape, then gently tap the inside edges with an eight-ounce hammer until the pane breaks free. Peel off the tape to remove any shards. Wear heavy gloves and safety goggles when removing broken glass.

* Pull out the old glazier’s points with needle-nose pliers.

* Take out the old glazing compound or putty, softening it with a hair dryer if necessary. Using a chisel or putty knife, scrape it out carefully to avoid gouging the groove. Then run a screwdriver around the frame to remove any remaining shards of glass.

* Sand the sash and paint the raw wood with linseed oil or thinned oil-base paint to prevent absorption of oil from the glazing compound.

* Measure the opening for the new pane and deduct one-eighth inch from both dimensions. The new glass should be as thick as the original.

* A glass supplier, hardware store or home center will cut a pane to your specifications. However, you can cut glass to size yourself. Wear work gloves and safety goggles. Measure carefully. Place the glass on a firm surface, well-padded with newspaper. Use kerosene or turpentine to wipe the line to be cut, then score with a glass cutter in a single stroke along a non-skid metal straightedge. Place the scored line over a nail, pencil or thin dowel. Press down firmly to break the glass. Or grasp the glass on both sides of the line and sharply snap it apart. Practice on scrap glass until you get a feel for it.

* Rub a piece of glazing compound between your palms to make a one-eighth inch thick rope. Working outside, press this rope around the opening.

* Set the new pane in place and press it gently against the compound, flattening the rope. The excess compound should squeeze out around the glass edge.

* Install glazier’s points every four to six inches. (The push type with tiny projection “ears” is easier to install than the traditional diamond-shaped points.)

Be sure the points are snug against the pane. Use an old screwdriver or stiff-bladed putty knife to push them halfway into the wood.

* Make a slightly thicker rope (about three-eighths inch) of compound. Press this rope over the glazier’s points and against the pane.

* Hold the putty knife at an angle and draw it across the compound to form a smooth triangular bead. Scrape away any excess that oozed onto the interior pane.

* When the compound has cured (check the label for curing time), paint it to match the window frame. Overlap the glass with the paint by about one-sixteenth inch to seal out moisture.

Casement Windows

Replacing a pane of glass in a casement window is much the same as for double-hung windows except that the pane is held by spring clips instead of glazier points.

* Remove the broken glass, spring clips and old glazing compound. Then paint the metal frame to prevent rusting.

* Apply a thin bed of glazing compound to the frame and press the glass gently against it.

* Insert the spring clips in the holes provided for them in the sash and press them into position.

* Apply more compound to the edges of the glass and frame. Draw the putty knife over the compound at an angle to form a triangular bead.

The glass in some aluminum storm windows is held in place by a gasket that must be pulled from under the retaining lip.

* Wearing gloves, remove the damaged glass from the frame. Run a screwdriver around the frame to clear away small bits of glass.

* Have new glass cut about one-thirty-second inch smaller than the frame. Lay the new glass in the frame carefully. Wear gloves.

* Replace the plastic gasket by pressing it under the frame lip with your thumb.

Start at the corner and work along the frame.