Timber Bay & Bow Windows

What Is a Bay Window?

A bay window is not a single window — it is an assembly of three or more windows set at angles to project outward from the wall of a building. The angled side windows (called cheeks) are typically set at 30°, 45°, or 90° to the front window. This creates a wider opening, floods the room with light from three directions, and adds usable floor space inside.

Bay windows became the signature feature of Victorian terraced houses from the 1850s onward. By the Edwardian period, they were standard on almost every new-build house in London. Today, they remain one of the most desirable architectural features in British residential property — and one of the most complex to replace correctly.

Bay vs Bow

• Bay window — flat panels joined at defined angles (typically 3 panels at 30° or 45°). Sharp, geometric projection. The most common type in Victorian and Edwardian houses.
• Bow window — curved panels forming a gentle arc. More common on Georgian and Regency properties. Requires individually angled frames to approximate the curve.

Both types can use sash windows or casement windows depending on the period and style of the property.

Sash Bays vs Casement Bays

The choice between sash and casement for your bay depends on the property.

• Sash bay — the historically correct choice for Victorian homes (1840s–1900s). Sliding sash windows in the front and both cheeks, with matching horns, glazing bars, and profiles. This is what conservation officers expect to see on a Victorian terrace.
• Casement bay — appropriate for Edwardian, 1920s–1930s, and modern properties. Opening casements in the front, fixed or opening cheeks. Simpler, wider sightlines.
• Mixed — some bays combine sash or casement opening panels with fixed picture panels. The cheeks might be fixed while the front window opens, for example.

Why a Site Survey Is Essential

Bay windows are the one product where we strongly recommend a site survey before ordering. Here is why:

• Nothing is square — after 100+ years, Victorian bay structures settle, twist, and lean. The three openings are rarely the same size. We template each opening individually.
• Structural assessment — the bay is supported by a cantilevered floor structure or corbelled brickwork. If the support has deteriorated, the bay may need structural work before new windows go in. We identify this during the survey.
• Matching the original — the moulding profiles, horn style, glazing bar proportions, and sill details must match the original if you are in a listed building or conservation area. We take detailed measurements and photographs of the existing windows.

Surveys are free within the M25 and Home Counties. Book yours here.

Specification

• Timber — engineered Accoya or premium hardwood. Consistent profiles across all windows in the bay.
• Glazing — double or triple glazed. Slim double glazing available for heritage applications.
• Security — PAS24 multi-point locking. Ground-floor bays are a common burglary point — proper security hardware matters.
• Colour — any RAL colour, full Farrow & Ball range. Dual colour available. All windows in the bay colour-matched from a single factory batch.
• Bars — Georgian bars, cottage bars, or plain glass. Consistent bar pattern across all windows in the bay.
• Finish — factory spray-finished with Sikkens coatings. 5-year paint warranty.
• Warranty — 10-year comprehensive warranty on timber and sealed glass units.

Guide Pricing

Bay window pricing depends on the number of windows, their individual sizes, and the specification. The most accurate way to price a bay is to configure each window individually in our 3D configurator, or book a free survey and we will provide a detailed quotation.

Areas We Specialise In

Victorian and Edwardian bay windows are our core business. We work extensively across London's bay window streets — from the grand stucco bays of Kensington and Chelsea to the classic red-brick bays of Clapham, Fulham, and Wandsworth. We also cover Hertfordshire, including St Albans and Harpenden.

For supply-only orders outside London, see our trade supply page. We deliver nationwide.