Window Repairs: Reglazing Windows

Reglazing a broken window-pane is a simple job for the home handyman. If the window is on a lower floor and can be easily reached from the outside, the reglazing can be done with the window in position in the framework. If the damaged pane is in an upper-floor window it will be found safest to remove the window to replace the damaged pane.

Sash windows may be removed as explained in ’Replacing a Sash Cord’. Wooden casement windows may be removed by releasing the screws securing the hinges to the framework. Metal casement windows may be found difficult to remove, in which case the reglazing of upper floor windows will have to be done from a ladder.

The first job is to remove all the broken pieces of glass. This should be done carefully, using several thicknesses of cloth to hold the broken pieces of glass. For safety’s sake it will be found best to get rid of the broken glass by placing it in a dustbin immediately it is removed, but one small piece should be retained for deciding the weight of the glass when purchasing the new pane. It should here be explained that glass is sold by weight and the description of the glass is governed by the weight in ounces per square foot; as glass is obtainable in a variety of thicknesses for different purposes it is necessary to give the weight of the glass when buying a new piece. In most cases window-panes are of 21-oz. glass, but if a piece of the old pane is produced when purchasing a new pane, this will enable the supplier to check on the weight.

To replace the damaged pane it will be necessary to remove all the old putty. This may be done in one of two ways : The putty may be cut from the recess in the frame by using a hammer and a hacking knife, but this is rather a laborious method of doing a simple job and it will be found much easier to remove the putty, with less risk of damage to the frame, by softening it. Hardened putty may be softened by the application of heat. In the case of a window-frame the method of heating and softening the old putty may be by an electrically-heated soldering iron. Every piece of the old putty should be removed, also any old nails or sprigs securing the old pane of glass inside the rabbet.


The replacement materials consist of a piece of glass of the correct weight, which should be a in. smaller all round than the inside dimensions of the rabbet. Also required is some glazier’s putty (this is best purchased in tins) and some glazing sprigs (as described in Nails and Screws and Their Uses). The tools consist of a light hammer, chisel, putty knife and a pair of pliers. The pliers are used to take off a small piece at each of the four corners of the glass before fitting it into the frame. The corner should be gently nibbled between the jaws of the pliers, and it is only necessary to remove a very small amount of glass. This is done to minimize the risk of breakage when replacing the glass. The glass should be dry and is best handled by folding several layers of newspaper over the sharp edges. The inside edges of the rabbet should be treated before fixing the glass in position. Treatment consists of painting to preserve the woodwork; this may be done with a quick-drying aluminium priming paint, or the preservative coat may be ‘knotting’ which is used for sealing knots in new wood before painting it.

reglazing windowsThe next part of the job consists of placing a layer of putty on the face of the rabbet which meets the inside with the glass (see image right). To do this, work the putty between the hands until it is quite soft and spread a layer of the soft putty on the newly painted rabbet with a putty knife. With this done the glass should be placed on this cushion of putty and gently, but firmly, pressed down at the edges on the putty cushion until the cushion shows a flat surface through the glass all round the pane. The layer of putty in this cushion need only be very thin.

The next job is to drive in the glazing sprigs. The best tool for this is a very light hammer, or the flat side of a chisel. Care must be taken when driving in the sprigs not to assert too much pressure on the glass or it may crack. The first sprigs positioned should be one at each of the four sides of the glass, but these should not be placed exactly opposite each other or the glass may crack. After this, more sprigs should be driven in at a distance of about 4 in. to 6 in. apart. When the nailing has been completed the putty should again be softened by working it between the fingers and a thickness of putty should then be pressed into the remaining part of the rabbet (see above image).

Finally, shaping of this thickness to a bevel is done with a putty knife and this may require several attempts before attaining perfection. The blade of the putty knife should rest on the top edge of the rabbet and the knife be drawn downwards to make a neat bevel. If the putty tends to stick to the knife this may be overcome by wetting the blade. A final finish is attained by gently brushing the putty bevel with a clean paint-brush. With the bevel finished, the knife should be used inside the window to trim away any surplus putty exuded from the thin cushion under the glass. The putty should be left for several days to harden before painting it. When reglazing metal windows, sprigs of course are not used and a special metal window glazing putty is used.

Reglazing Leaded Windows:

The panes of glass in leaded windows are held in position by thin strips of lead and not by putty or nails. The damaged glass should be removed by pressing from the inside to force the pieces outwards and the hands should be protected by several layers of thick cloth. The pieces are pushed outwards to spread and bend the edges of the lead strip. A piece of the old glass should be produced when buying a new pane to obtain a piece of the correct weight. It may be necessary to lever the edges of the lead strip gently forward to insert the new piece of glass. When this is done the edges of the lead should be pressed against the replaced glass with the fingers, final pressing should be done by rubbing the edge all round with a piece of soft wood.

Any corners of the lead strip which have split should be repaired with a soldering iron. Care should be taken not to overheat and melt the lead of the main strips.

06. July 2011 by admin
Categories: Internal Repairs, Windows | Tags: , | Comments Off on Window Repairs: Reglazing Windows


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