Sash Window Repairs in London: Cords, Rot, Glass and Draughts

Four faults account for almost every sash window we are called to: a snapped cord, so the sash crashes down or will not stay up; paint and swelling, so it will not budge at all; soft or rotten timber, usually in the bottom rail or the sill; and draughts around the meeting rail. All four are repairs, not replacements. We work sash by sash, keep the original timber and glass wherever it is sound, and leave the window opening and closing the way it was built to.

• New sash cords, weights re-balanced, pulleys serviced or replaced
• Rot repaired with resin or timber splices rather than full replacement
• Perimeter brush and blade draught-proofing systems fitted
• Cracked and misted panes replaced with matching glass
• Sensitive to conservation area and listed building requirements

A sash that jams or crashes down is almost always a snapped cord. We take the sash out, dress the box and pulleys, fit new pre-stretched cords and re-balance the weights so the window glides again. On heritage windows we keep as much of the original timber as possible.

Draughts are the other big complaint. A properly fitted brush-seal system stops the whistle around the meeting rail and along the sides without changing the look of the window from either side. Combined with cord repair it can bring a 100-year-old window back to feeling almost new.

Rot is far more localised than it looks. Water collects where end grain sits in a puddle, which in practice means the bottom rail of the lower sash, the joints at its corners and the front edge of the sill. The timber a few inches away is usually dry and perfectly good, so cutting out the soft section and splicing in matching timber, or filling smaller losses with a two part resin, keeps the original window and the original glass. A window is only genuinely beyond repair when the joints have opened up along the whole rail.

Sashes that will not move are most often painted shut rather than mechanically broken. Decades of coats build up in the rebate and across the parting bead, and one careless redecoration seals the lot. Freeing the sash, cleaning the rebate back and easing the beads is a controlled job rather than a forceful one: the glass in an old sash is thin and often original crown or drawn glass, and it does not survive being levered against.

Two things people ask about that we will always be straight on. Slim double glazed units can be fitted into deeper sashes and make a real difference, but they add weight, so the cast iron weights have to be changed to match or the window will not balance. And in a conservation area or on a listed building the profile, glazing bar widths and glass type can be controlled, so a like for like repair is usually both the correct route and the cheaper one.

How the repair works

1. 1. Survey We inspect the box, sash, cords, pulleys and glass. You get an honest assessment of what needs doing.
2. 2. Bench work For heavier repairs the sash comes out and is worked on before being refitted so your room isn't open all day.
3. 3. Rebalance & seal Weights matched to sash weight, cords stretched and tied off, draught seals fitted and painted in.

Useful guides

• Single vs Double Glazing Repairs

Call Mark on 07535 916982 or request a callback.