Replace a broken window pane

There is no need to call a specialist when a window pane breaks. It is quicker and much cheaper to replace it yourself.

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Before you start
When buying glass, tell the supplier the size of the panes and where they are situated. He will advise on the thickness and type of glass that should be used to conform to the relevant standards (AS 1288/NZ 4223). As a general guide, the smaller the panes, the thinner the glass. However, the position and use of the pane may be such that safety glass is called for. It is very important, as a matter of safety for yourself, your family and your visitors, that you ensure that any new glass you install meets the proper standard.

For wooden windows use linseed oil, universal or acrylic putty; for metal windows use metal casement, universal or acrylic putty. You will need about 1kg of putty for 3.5m of frame. Brown putty is available for windows that are to be finished with preservative stain. Broken glass in doors is replaced in the same way as for wooden windows, unless the door has been glazed with beads which are replaced as for square-edged double glazing units.

STEP 1
Mould the putty in your hands to get it soft and pliable. If it sticks to your hands, try wetting them, or take some of the oil out by rolling the putty on kitchen paper.

STEP 2
Hold the pliable putty in the palm of your hand and squeeze it out between the thumb and forefinger to form a layer about 3mm thick in the rebate all the way round the window.

STEP 3
Press the glass carefully into the rebate so it is well bedded on the putty. Press it round the edges only, taking care not to push too hard in one place – and never in the middle of the glass. It could break and cause serious injury.

STEP 4
Fix the glass in place with glazing sprigs inserted into the window about 250mm apart. Knock them in with the edge of the chisel or with the back of the hacking knife, sliding it along the face of the glass. The heads of the sprigs should protrude about 5mm from the frame. Trim off excess bedding putty on the inside of the pane.

STEP 5
Apply more putty to the front of the glass to fill the rebate, and smooth it off with a putty knife to form a neat triangular line of putty that covers the heads of the sprigs and lines up with the putty on the inside edge. Make neat mitres at corners.

STEP 6
Leave the putty for about two weeks to harden slightly before painting it. When you paint it, allow the paint to spread onto the glass by 3mm to keep out the rain.