BB-01Popular
45° three-facet bay
A wide front facet with angled sides set at 45°.
Quote this layout: 45° three-facet bayWindows
Bay & bow windows
A bay window projects from the wall in angled facets, usually three. A bow uses four or more shallower facets to form a gentle curve. Both add light and a little floor space, and both need careful surveying, because the old frames often carry part of the structure above.
See all 5 layoutsIn many older homes the original timber bay is load-bearing. It may support a bay roof, a bedroom bay or brickwork above. uPVC frames are not designed to carry that weight, so where it is needed we fit bay support poles inside the corner couplings to take the load down to the cill or brickwork below. They go in before the old frames come out. Skipping this step leads to cracked frames, sagging heads and sashes that will not close.
Each facet can be a casement, flush casement or sash, matched to the rest of the house. The angles are measured on site with a bay template rather than assumed, because older bays are rarely perfectly square or symmetrical.
Look at the roof and cill while you are planning. A leaking lead or tiled bay roof, or a cracked concrete cill, is best dealt with while the windows are out. Any extra work is listed separately on your quote.
5 standard layouts
The layouts we fit most in UK homes. Every one is made to measure, and you choose the opening side, colour and glass. Need something different? Tell us and we’ll draw it for you.
BB-02
30° three-facet bay
A shallower bay with sides set at 30°.
Quote this layout: 30° three-facet bayBB-03
Box bay (90°)
A square bay with sides at right angles to the front.
Quote this layout: Box bay (90°)Drawings are viewed from outside and are not to scale. Dashed lines meet at the hinge side. Sizes are typical starting points; we measure every opening at survey.
Why choose bay & bow windows
01
Structural check
We check whether the existing bay carries load before we quote.
02
Bay support poles
Fitted inside the corner couplings where the bay is load-bearing.
03
Any style per facet
Casement, flush casement or sash, matched to the rest of the house.
04
Measured angles
Facet angles templated on site for a tight, square fit.
At a glance
Exact figures depend on the system and options you choose. We confirm them on your written quote.
| Configurations | 3-facet bays (typically 45° or 30°); 4-, 5- and 6-facet bows |
|---|---|
| Glazing | Double glazed as standard. Triple glazing available on request |
| Energy | Meets Building Regulations Part L for replacement windows (U-value 1.4 W/m²K or better, or WER band B or above). A-rated options available |
| Ventilation | Trickle vents fitted where Part F requires them, including wherever the old windows had them |
| Safety glass | Toughened or laminated glass in critical locations, including any pane within 800 mm of the floor (Part K) |
| Colours | White, cream, woodgrain foils and solid colours including anthracite grey (RAL 7016), black and Chartwell green |
| Structure | Bay support poles where the bay is load-bearing; new cill or roof flashing if required |
About bay & bow windows
How do I know if my bay is load-bearing?
If there is a room, a roof or brickwork directly above the bay, assume it may be. We check on site and include support poles in the quote when they are needed.
Do you replace the bay roof as well?
We can replace or re-flash small lead or tiled bay roofs as part of the job where needed. Roof work is priced as a separate line on your quote.
What is the difference between a bay and a bow window?
A bay usually has three facets set at a sharper angle, which gives a squarer projection. A bow has four or more narrower facets set at shallow angles, so it reads as a curve. Curved bows are common on 1930s semis.
Similar styles
Suits most homes
Casement windows
Hinged and fixed panes in almost any layout. The standard window for most UK houses.
- 34 layouts
- Side-hung
- Top-hung
- Fixed lights
Victorian & Georgian
Sash windows
Vertical sliders in the proportions of a box sash. No rattles, cords or repainting.
- 6 layouts
- Vertical slider
- Tilt-in cleaning
Timber look
Flush casement windows
Sashes sit level with the frame, like timber joinery. Woodgrain and heritage colours.
- 6 layouts
- Sits flush
- Heritage colours
- Woodgrain
Free survey · written quote · no obligation
Get a price for bay & bow windows.
Send rough sizes and a few photos for an estimate. Or book a free survey and we’ll measure everything ourselves.