The Hidden Heroes of Period Sash Windows – The Wedges and Pins That Keep Old Windows Honest
Folding wedges – the ancient solution that keeps old timber windows square. They are often invisible; buried deep within the joints of the frame of a sash window, holding it all together. Some old timber windows have massive timber sections and no screws or adhesives hold them together. Others are held by small folding wedges of wood – two wedges of wood that are pushed together to make a thicker and taller section of wood. When a joiner shows you how to use a pair of folding wedges, it suddenly makes perfect sense.
Folding wedges are a clever way of filling a space, and old joiners were particularly pleased with their use for closing gaps in corner joints. Essentially a pair of wedges, one pushed against the other from opposite ends, the greater the pressure on them the taller they become. So by pushing a pair of folding wedges into a corner of a sash frame a considerable space can be filled with a single block of timber, all without having to cut and join a new piece. Joiners appreciate that hardwoods are prone to seasonal growth and shrinkage, and for years they have found that folding wedges are the perfect way to accommodate these changes without having to try and combat them.
In addition to the use of wedges, the bead system fulfils a similar role in the sash window. The staff bead and parting bead are the small sliver of timber that run along the sash box of the window, within which the sashes of the window are able to travel up and down. The staff bead is pinned at regular intervals to the linings with small brads or pegs of wood, as are the ends of the parting bead. This bead system has a number of functions, including to stop the sashes from rattling within their sash box, and to stop them from twisting out of square under their own weight. If one of the beads is lost, the sash below will start to drop slightly, allowing draughts to enter, and for the latches of the window to no longer meet in the correct position. There is a useful background explanation of Historic England’s guidance on historic glazing repairs.
What is particularly pleasing about these two aspects of the sash window is that they have not changed. Joiners still use the same methods to make folding wedges and to pin the beads as were used centuries ago. The logic behind the method is the same and Historic England’s guidance on historic glazing repairs is written with the assumption that the traditional methods will be used for repairs to period frames. If you want Sash Window Repair, contact www.sashwindowpreservation.co.uk/services/sash-window-repair
The humble wedge, a simple triangle of wood, has always been a dull thing to look at but it has been holding sash windows square for hundreds of years. A simple pair of folding wedges are all that is needed to keep a heavy timber frame square, and if properly used, they will continue to do so for another hundred years.