An occasional cracked or broken window is not uncommon in most homes and is a typical Home Repair item. It can be easily and safely repaired in most cases. Small, easy-to-get-to panes of glass can usually be replaced from the outside without the extra effort of removing the entire sash. If the window is larger or, not at ground level, it is advisable to remove the entire sash to work on it.
Place a dropcloth of some sort on the ground to catch the broken shards of glass as they are removed to avoid them getting on the ground where they’ll be more difficult to find. As a safety precaution, don your Personal Protective Equipment (PPE) -leather gloves and safety glasses or goggles are recommended.
Carefully remove the old glass and glazing material. Hard-to-remove pieces can be gently gripped with pliers for extra leverage. Scrape out all the old glazing material from the wooden frame. A heat gun (or, hair dryer) and putty knife or chisel may be used to get the hardened pieces. Be careful not to damage the wood frame.When all the old material has been removed, clean out the frame. If the wood from where the glazing material was removed is bare, apply a sealer to prevent absorption of the glazing material oils into the wood and premature drying out.
Measure the opening for the proper dimension of the replacement pane. Double check all measurements and don’t measure too tight. Most hardware stores will cut a piece of glass to your measurements. Set the replacement glass into the sash frame to confirm the fit. Remove the glass and apply a small bed of glazing material prior to re-inserting the glass.
Place the glass pane into position and secure it using glazing points. Push the glazing points into place using the edge of a putty knife or a screw driver. For large panes, place a glazing point every six inches around the perimeter. For smaller panes, two per side is sufficient. Avoid applying direct pressure to the glass itself to avoid breakage.
Apply a bead of glazier’s putty around the perimeter of the pane and pres into place. Apply a large enough bead and trim it by running the putty knife along each side at an angle. Long steady strokes of moderate pressure will result in a smooth, uniform glazing seal. Any excess material can be easily removed with a putty knife. Remove any excess from the interior side. After the specified curing time, the putty should be painted. Extend the coat of paint slightly onto the glass for a complete seal. Any putty left unpainted will rapidly dry out.
A double glazed insulated unit should be replaced by a professional. The space between the panes is filled with nitrogen to replace the air and the moisture that comes with it to prevent fogging.
Generally, any door glass or in high traffic areas must be tempered or, safety glass. If it is not, that might be a good candidate for your next Home Improvement project.
Further information from respected sources: