The method
How a box sash comes apart, and goes back together.
Seven steps, in the order we do them. What each part costs is on the work and prices page.
The Survey
We look at every window from inside and out: the sill, the bottom rails, the putty, the cords, how each sash runs and what has been painted shut. A survey takes about forty minutes for an ordinary house. The quote comes by email within a week, window by window, so you can choose which ones to do now and which can wait.
Survey visits are free within Bath and £40 further out, taken off the work if you go ahead. How the day itself runs is on the visit page.
Taking the Sashes Out
The staff beads are eased off with a broad knife so they can go back on, not snapped and thrown away. The lower sash comes out first and its cords are cut and tied off, so the weights do not drop into the box. Then the parting beads come out, then the upper sash.
The pocket pieces at the foot of each pulley stile are opened to reach the weights. Inside there is usually a century of dust, sometimes a newspaper, now and then a child's marble. We put back whatever we find.
Repairs
Rot is cut back until the chisel finds sound timber. A new piece of matching timber is glued in, left a little proud and planed back to the profile of the old. Sills get the same treatment, or a new nosing if only the front edge has gone. Glazing bars that have snapped are rebuilt rather than patched. Filler is only ever for dents.
I will go on about glass for a moment, because it is the part people ask us to throw away. The panes in a Georgian or Victorian sash were made by spinning a disc of molten glass or by blowing and flattening a cylinder, and they are never quite flat, which is why the street outside wobbles a little as you walk past. That ripple cannot be bought new. When we reputty a sash we take the panes out whole wherever we can, number them, clean the rebates back to bare timber, prime them and bed the same glass back in linseed putty. If one breaks, and now and then one does, we replace it from a box of old panes saved from windows that could not be saved, so the new one wobbles like its neighbours. People ask whether slim double glazed units would be warmer. They would be a little warmer, but the sash would need to be thicker and heavier, the weights changed, the glazing bars made deeper, and the window would never look the same again from the street. For most houses in this city a well draught proofed sash and a good pair of curtains does nearly as well, and keeps the old glass, which I think is worth keeping.
Draught Proofing
A narrow slot is routed into the staff beads and the parting beads, and a brush pile seal is pressed into each. The meeting rails get a seal along their length, and the bottom rail a seal that meets the sill. Nothing is stuck on and nothing shows from outside.
Done properly the sash still slides with one hand. If a draught proofed sash fights you, the beads are too tight, and we set them again before we leave. The price for this, cords included, is on the work and prices page.
Cords and Weights
Waxed cotton cord, one length for each side of each sash, knotted into the weight and nailed into the groove in the sash stile. If the glass has changed, the weights change too: a sash with heavier glass needs heavier weights or it creeps down, and one with lighter glass creeps up.
Pulleys are freed, cleaned and oiled. A seized pulley that will not free is replaced with a plain one of the same size, set into the same mortice.
Putty and Paint
Loose and cracked putty is cut out and replaced with linseed putty. It needs about two weeks to skin over before it takes paint, so the first coat often comes on a second, shorter visit. Three coats of linseed paint in all, with the paint carried just onto the glass so rain runs off rather than into the joint.
Back In, and Balanced
The sashes are rehung and the beads refitted, with the old pins where they will take them. Each sash is tried at the top, the bottom and halfway. It should stay where it is left, slide with one hand and lock without a shove. If one creeps in the first year, we come back and set it at no charge.