How To Fix A Broken Window Pane In A Wooden Frame


A broken window is not only a security risk; it is also dangerous particularly if there are small children around. The answer is to mend it as quickly as possible.

When re-glazing, the new glass has to be fitted from outside. This presents no problem if you are working on a ground floor window; but if the broken pane is on an upper floor, it is usually easier to remove the window from its frame.

How To Fix A Broken Window Pane In A Wooden FrameYou can simply unscrew the hinges of a casement window, but if you have a sash window you will need to remove the beading and prise out the nails holding the sash cord.

1. Start by carefully working loose the large fragments of pane, then tap out the smaller pieces. If you work with the window lying flat on several large pieces of newspaper, clearing the broken glass once you have finished will be a lot easier and safer.

2. If the smaller, edge pieces prove difficult to remove, cover the window with a cloth to prevent the glass flying about then smash the fragments down to the facing putty.

3. Remove the cloth, then chop out the putty with the glass embedded in it. The proper tool for this job is a glazier’s hacking knife, but you can do it with a hammer and old wood chisel. Remove the bedding layer of putty, taking care not to damage the wood in the process.

4. Pull out the sprigs — triangular, headless nails that hold the glass in place — with a pair of pincers and clean out the rebate with a stiff brush. Once you have determined the size of the new glass, you will need to paint the rebate with primer —this could take 45 hours to dry, so don’t start the job too late in the day.

Measure the opening for the new pane. Check both the height and the width at at least three points in case the frame is not square. Subtract 3mm from the height and width to allow sufficient clearance — 6mm if the frame is slightly warped. And if the frame is an irregular shape, or if you are in any doubt, make a paper template to take along to your glass merchant.

TIP: When giving measurements to a glass merchant, it is usual to give the height before the width. This way, you can ensure that the pattern is the correct way up (vertical), if you are buying frosted or patterned glass for your window.

Once the rebate has dried, you can begin to press a thin, bedding layer of linseed oil putty into the rebate angle. The putty will need to be of the right consistency — pliable but not sticky — if it is to hold the glass in place and form a watertight seal. Work it in your hands to warm it, which will make it easier to use. If it is too wet or sticky. Knead it gently between the palms of your hands or place it between folds of newspaper to remove any excess moisture and oil. If it’s too dry, add linseed oil. Roll it out in your hand to form a thin sausage, and press a layer about 4mm thick into the rebate.

5. Once you have applied the bedding layer of putty, put the glass in position. Lean it in from the bottom, then push around the outside of the frame, not the centre, with a pad of cloth to protect you from any glass slivers which may be left in the frame. As you do this. The putty will ooze out gently.

6. Next, tap in the new sprigs with the side of an old chisel.

Slide the chisel along the glass to reduce the impact and avoid any damage to the new pane. The sprigs will be buried by the facing putty when the glazing is finally completed.

7. Apply the facing putty in a sausage using the heel of your hand or thumb to press it into position. Trim it off to 45° by drawing the blade of your putty knife (or scraper) along it. The finished height of the facing putty must be no higher than the inside level of the frame, so that it is invisible from the inside. For a neat finish, mitre the two lines of putty at corners.

Leave the putty to mature for about four weeks before painting.

Carry the paint layer just beyond the edges of the putty, onto the glass. This will provide a waterproof seal and prevent the putty from shrinking or cracking in the future.


In some wooden frames, the glass is not held in by putty, but by wooden beading pinned to the frame.

To remove the old glass, knock out the larger pieces, then prise off the beading with an old chisel, starting at the centre of each strip. Pull out any remaining pins with pliers.

Chop out the pieces of broken glass and putty. Prime any exposed wood and leave to dry.

Apply a thin layer of bedding putty to the rebate, and press the pane into place. Then apply a thin layer of facing putty to seal the gap under the beading.

Fit the beading strips into place — do the top and bottom ones first — and pin with small

oval nails or panel pins at 100mm intervals. If the old strips were damaged, cut new lengths.

Scrape off any surplus putty with the point of a knife. Paint the beading to protect it.

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