Bay-window seating is one of the most distinctively-London joinery briefs we get. The bay window is a feature of Victorian and Edwardian housing that’s almost universal in the period stock — every front room has one, sometimes the master bedroom has one too — and the seating brief comes up because the bay is a notoriously awkward bit of floor area to use otherwise.
Why the bay window is awkward without a seat
A typical Victorian / Edwardian front bay window has three planes — a centre section facing the street and two splayed returns angling out from the room. The geometry is around 30° on the returns. The floor area inside the bay is too small for a piece of standalone furniture (a sofa or even an armchair won’t fit comfortably against the splayed wall), too oddly-shaped for floor lamps or side tables to feel right, and usually has a radiator directly under the centre window.
The result, in most period homes, is a bay window that’s underused — empty floor space, or filled with a single chair facing inward awkwardly. Bay-window seating is the joinery solution that converts the dead floor area into useful storage and a place to sit.
Three sizing decisions
Depth. The single biggest variable. A 450mm-deep seat is OK for a quick perch but too shallow to read comfortably on. 500–550mm is the comfortable adult depth. Period bays vary in actual depth from 350mm to 900mm; deeper-than-550 isn’t useful for sitting (your knees are too far forward) so the excess depth becomes storage volume or a slim shelf at the back.
Return geometry. Square bays (rare in Victorian / Edwardian London) get a straight bench. Splayed bays (the common pattern) get a faceted three-section seat that follows the bay angles. Semi-circular bays (very rare; mostly seaside-town housing) get a curved bench — significantly more complex, ~30% premium over straight.
Sill height. Determines back-rest height. Most Victorian sills are 800–900mm above the floor. With a 400–450mm-tall seat structure, you’re left with 350–500mm of back-rest before the window glazing starts. Enough for comfortable seating with one or two cushions; not enough for fully-supported lounging.
Storage configuration
Three patterns. Pick based on what you’ll store:
| Pattern | Best for | Trade-offs |
|---|---|---|
| Lift-up lid (single void underneath) | Big bulky items — bedding, suitcases, Christmas decorations | Less accessible day-to-day; needs both hands to use |
| Two or three drawers across the seat front | Everyday small items — toys, kids’ shoes, hats, books | Less total volume; drawers don’t sit comfortably on the splayed sections of three-sided bays |
| Hybrid: drawers in centre, lift-up on the returns | Mixed-use rooms (kids’ toys + adult bedding) | More complex to design; slight premium |
Most clients pick drawers — they’re easier to live with day-to-day and look more architectural. About a third pick lift-up for the volume.
The radiator question
Almost every Victorian and Edwardian bay window has a radiator directly under the centre window. Three options:
1. Remove and relocate the radiator. Adjacent wall, often the wall opposite the bay. Plumber visit, ~£250-£400 for a short relocation in the same room. Cleanest design outcome.
2. Build the seat over the radiator with a grille. The seat front section above the radiator is replaced with a perforated brass or wooden grille. Heat output drops 15-25% through the grille (compared to direct convection), which matters in winter but is usually acceptable. No plumbing work needed.
3. Replace with a vertical radiator. Modern slim vertical radiator on an adjacent wall instead. Better heat output than the grille option, costs roughly £200-£350 for the new radiator plus plumber.
We see option 1 about 50% of the time, option 2 about 40%, option 3 about 10%.
Mouldings and finish
The detail that makes a bay seat read as original rather than added-on: the seat needs to scribe into the existing skirting and architrave, not replace them.
In a typical Victorian terrace, the skirting around the bay is part of a continuous run from the room’s main skirting line. The seat needs to either (a) sit on top of the existing skirting, with the skirting continuing under it, or (b) merge into the existing skirting at the corners, picking up the same profile. Removing the original skirting where the seat sits is the cheap option that always looks wrong afterwards.
Same for any architrave around the bay window itself — keep it visible, scribe to it.
Listed buildings and conservation areas
For Grade II (or higher) listed buildings, internal alterations technically need Listed Building Consent — but bespoke joinery that fixes only into the floor and not into any original mouldings or walls is usually fine without consent. Confirm with your conservation officer if in any doubt; we work alongside conservation officers regularly and can advise on what’s likely to be approved.
Conservation Areas don’t affect interior joinery at all — they’re an external-only constraint.
Cost (London 2026)
| Scope | Range |
|---|---|
| Single straight bench, 1.5–2m wide, two drawers | £1,400–£1,900 |
| Three-sided bay seat, faceted, with storage | £1,900–£2,900 |
| With integrated radiator cover | +£300–£500 |
| With built-in bookshelves up the window reveals | +£600–£900 |
| Bespoke upholstered cushion | £180–£320 depending on fabric |
For more on what we build for bay-window seating specifically, see the bay-window seating service page or get in touch for a free site survey.