Sash window replacement

Our replacement heritage sash windows are made to match the original as closely as the eye and the record allow. Before any timber is cut, we survey the existing window, take off its sightlines and moulding profiles, and note the depth of the box, the meeting rail, the horns and the glazing bars. These details are what give a Georgian or Victorian sash its proportion, and getting them right is the difference between a window that disappears into the facade and one that announces itself as new.

Each sash is built using traditional haunched mortise and tenon joints, pinned and drawn tight for strength that will outlast modern comb‑jointed alternatives. We work in joinery‑grade softwood, Douglas fir or mahogany depending on the building, the exposure and the finish the owner wants. Timber is selected for straight, close grain so the finished window holds its shape through London's damp winters and warm summers, and every component is primed on all faces before assembly so no surface is left unprotected.

Modern performance is engineered in without disturbing the historic appearance. Concealed draught‑proofing runs in the staff and parting beads, so the rattle and cold draughts associated with old sashes are gone while the window still slides freely on its cords or spiral balances. High‑performance ironmongery, discreet security stops and quiet, balanced operation are specified as standard. Where a property sits in a conservation area, we can supply single glazing with traditional putty lines to preserve the reflective quality of the original glass, or slim double‑glazed units where the planning position allows a warmer, quieter home.

Because the windows are made by hand in London rather than pulled from a catalogue, there is no standard size and no compromise on the awkward openings that period buildings are full of. Splayed reveals, cambered heads, curved sashes and non‑standard bar layouts are all part of ordinary work for us. Every window is hand‑painted rather than sprayed, building up a finish that sits into the grain and can be maintained in place for decades rather than needing to be stripped back.

Like‑for‑like matching is the heart of a good heritage window replacement. A window that copies the original glass area but ignores the moulding profile, the horn shape or the meeting‑rail depth will always look subtly wrong, and on a listed building or in a conservation area it will often fail to gain consent. Our process is built around removing that risk before manufacture begins.

We start by recording the existing windows in detail. We take physical templates of the mouldings, measure the sections, and photograph the horns, cills and glazing bars so that the replacement reproduces not just the size of the opening but the character of the joinery. Where original windows have already been lost or crudely replaced, we draw on surviving examples elsewhere on the building or on comparable properties of the same date to reconstruct an appropriate profile.

Glazing bars are a common failure point in cheaper replacements. True divided bars, with individual panes and putty lines, read very differently from applied bars stuck onto a single sheet of glass. We advise on the right approach for the building and the planning context, whether that is genuine single glazing, slim double‑glazed units with true bars, or a bonded bar arrangement that satisfies both the conservation officer and the desire for a warmer home. The aim is always that the finished window casts the same shadow lines and reflections as the one it replaces.

This discipline extends to the finish. We match paint colours to the existing scheme or to a specified heritage palette, and we hand‑paint every window so the coats flow into the corners and mouldings rather than sitting on the surface. For owners of listed and period buildings, this like‑for‑like approach is what allows a modern, draught‑proofed, secure window to sit invisibly within a historic elevation. It is also why our work tends to satisfy planners first time, saving the delay and expense of revised applications.