Sash window refurbishment
across London.

We refurbish sash windows on-site, in period properties across London and the Home Counties. Refurbishment, the way we work, means the original window stays — its frame, its glazing bars, its horns, its line — and only what's failed gets replaced. The thermal envelope changes; the look does not.

Most projects combine several of the services below. Almost every original sash can be brought back to running order; once it is, vacuum double glazing and draught-proofing handle the performance side. Listed-building work follows the same approach with an added round of conservation-officer engagement.

Frame refurbishment

Almost every original sash window can be brought back. Restoration starts with a visit to the property and a written quotation. From there, the principle is to save what we can and replace only what has failed.

The most common failure is rot at the bottom of the sash and at the cill — the parts of the assembly that catch rain. The fix is hand-splicing: cutting out the decayed timber, letting in new oak or matched softwood, epoxy-bonded and pinned, then planed flush.

Beyond rot, restoration covers the joinery and the box. Failed parting beads and staff beads are renewed in matched profile; loose mortice-and-tenon joints are wedged or re-glued; glazing bars are repaired in situ rather than swapped out. Where the box frame itself has lost its plumb — usually from settlement at the lintel or a softened cill — we reset and pack rather than replace. Stuck sashes are eased: paint build-up planed back from the meeting rail and parting bead, swollen timber relieved, the runs waxed.

Where pieces are missing or beyond economic repair, we match the original profile rather than swap to a stock substitute. Ironmongery is reused; where pieces are missing, period-appropriate hardware is sourced from specialist heritage suppliers — sash lifts, finger pulls, fitch fasteners, weights. Cracked panes are replaced; original crown or cylinder glass is retained wherever it survives.

The end result is a sash that closes properly, holds its position, and looks like itself again — the proportions of the original unchanged, the line of the building untouched. Full overview of our restoration service →

Cords, weights and pulleys

Sash cords stretch and eventually snap. Replacing them means dismantling the box, fishing out the broken cord and the weight, and rerunning new high-strength cord. The pulleys themselves rarely need replacement — most we encounter are still running cleanly after a century. We service them: oil the spindle, check the wheel, refit.

Where a sash has been weighed incorrectly — heavy sash, light weights, or vice versa — we re-weight it so it holds at any position without props. More on cord and weight replacement →

Vacuum double glazing for sash windows

The single biggest performance change available to a period window is vacuum-insulating glass. Two thin panes separated by a 0.3mm vacuum gap, sealed at the edges, supported by tiny invisible pillars across the surface. The whole unit is around 6mm thick — lighter than a single-glazed sash — and slots into the original rebate with minor frame adjustment.

U-values come out at 0.7–1.1 W/m²K — in line with new-build standards, often better than the masonry wall around the window. The line of the original glass is preserved; the glazing bars stay; the sash horns stay. From the street, the building looks the same. From the inside, the window stops being cold to the touch. Full detail on the retrofit →

Draught-proofing

The other half of thermal performance is air infiltration. An untreated sash leaks air around the meeting rail, the parting bead, and at the perimeter — easy to feel on a windy day. The seals are invisible from outside, don't change the way the sash slides, and cut air leakage substantially.

Draught-proofing is commonly specified on its own — a sensible first step for clients not yet ready to retrofit glazing — or as part of a fuller restoration. More on draught-proofing →

Listed buildings and conservation areas

For Grade II and Grade II* listed buildings, the conservation officer is the audience as much as the homeowner. The starting position is always retention: the original window stays unless it's structurally beyond economic repair. Where re-glazing is permitted, the modification has to be reversible — the original frame survives, with the work capable of being undone without damaging the underlying joinery. Vacuum-insulating glass fits this criterion; replacement of the frame does not.

In conservation areas, re-glazing is generally permitted. The frame stays; only the glazing changes.

Painting and finishing

Finishing comes in two scopes. The simpler is prime only — bare timber sealed with a multi-coat primer, with the topcoat left to you or your decorator. The fuller takes the exterior all the way through — primer, undercoat, topcoat — using mid-sheen, oil-modified water-based paints suited to period joinery. Either way, glazing is bedded and pointed in a matched scheme so the finished window reads as a single object rather than a recently-disturbed assembly.

Where the building sits in a conservation area, paint colours follow the wider street palette or the officer's recommendation.

Where we work

We work across a roughly 90-minute travel radius from north London — Cambridgeshire's market towns, Hertfordshire's Edwardian suburbs, the Buckinghamshire villages along the Chilterns, and across north and west London. The buildings span 250 years — late Georgian houses, mid-Victorian terraces, Edwardian Metroland semis, occasional Arts & Crafts cottages. The work is essentially the same on each: assess what survives, replace only what's failed, retain everything else.

The frame stays. The glazing bars stay. The line of the window stays. What changes is the performance.

View recent projects →