Bay & Bow Windows — London & the Home Counties
The window that gave the Victorian terrace its silhouette — and still the single most transformative replacement we fit. Structural corner posts, lead-lined roofs, cast-iron style detailing and A+ modern glass — a full bay swap in a day.
The structural corner post
Every bay we replace uses a steel-reinforced corner post at each fold — necessary to carry the load above on 45° splayed bays and any bay supporting first-floor masonry. The load transfer is designed before we survey the sash sizes.
Overview
A closer look at what makes the bay & bow windows range distinctive — the specification, the styles, the process, and the answers to the questions we get asked most.
Six-chamber uPVC or aluminium bay profile · steel-reinforced structural corner posts · lead-lined or GRP roof · argon-filled A+ glazing · Georgian bar & astragal options
Structural Corner Posts
Steel-reinforced bay posts carry the load above — essential for 45° splayed bays and box bays that support first-floor masonry.
3-, 4- & 5-Facet
Splayed bays for Victorian terraces, box bays for Edwardian semis and shallow bows for cottages — all built to your survey template.
Lead-Lined Roofs
Traditional lead-flashed or GRP roofs matched to the existing bay, with proper flashing back to the brickwork and stepped over the parapet where required.
Replacement in a Day
In most cases we remove the tired 60s or 70s bay and refit the replacement inside a single working day — no exposed brickwork overnight.
Heritage or Modern
Traditional splayed bays with astragal bars and dummy sashes, or clean contemporary square bays in aluminium — matched to the age of the property.
Kerb Appeal
The single most valuable retrofit for a Victorian or Edwardian terrace — a restored bay adds visible property value and lifts the entire façade.
Three material ranges, one configuration.
The bay & bow configuration is available across every one of our window ranges — the material choice is yours.
Engineered to the millimetre.
Every frame we install is made to your survey sizes with the following performance envelope as standard.
- U-value (whole window)
- 0.9 – 1.4 W/m²K
- Configurations
- 3-, 4- & 5-facet · splayed · box · bow (5- and 7-light)
- Structural posts
- Steel-reinforced uPVC or aluminium corner posts
- Roof options
- Lead-lined · GRP · pitched tile to match
- Max span
- 3.6 m front-to-front on a supported bay
- Install time
- Typical bay replaced in one working day
Bay & Bow Windows across London
and the Home Counties.
We install bay & bow windows across six counties — every project surveyed, made and fitted by our in-house team. Choose your county to read local knowledge, planning notes and recent work.
See all areas coveredBay & Bow Windows — installed.
A selection of recent installations across London and the Home Counties, photographed on site.
Practical answers.
Everything homeowners ask us about bay & bow windows — survey, lead times, guarantees and coverage.
Do I need Building Regs approval for a bay replacement?+
A like-for-like replacement on an existing bay is covered under CERTASS. If we're modifying the structural opening or replacing the roof, we may need to notify Building Control — we handle the paperwork either way.
Will the bay stay up while you replace it?+
Yes — we prop the load above with acrow supports before removing the original frame, then install the new structural posts and transfer the load. The brickwork above is never unsupported.
Can I keep the original lead roof?+
Usually yes if it's in good condition. Where the lead has failed or corroded we replace it with new milled lead in Code 4 or Code 5, or with a modern GRP roof for a longer service life.
What's the difference between a bay and a bow?+
A bay window has three, four or five flat facets meeting at angles (usually 45°). A bow window is a shallow curved projection made of five or seven narrow lights. Both are supported the same way.
What affects a bay window replacement?+
The number of facets, frame material, roof condition, structural supports and surrounding masonry all affect the specification. We survey the load path and existing roof before manufacture.
Enquire about
Bay & Bow Windows.
Speak with our design team, book a home survey, and receive a fixed written quotation — all with no obligation.
Call · 020 3633 0405