Heritage & Planning
Listed building windows
We design, make and install timber windows for listed buildings across London and the Home Counties — built to satisfy listed building consent and conservation officers, with authentic profiles, true glazing bars and putty-line detailing. Every project begins with the planning rules for your specific property, not a standard product.
Replacing windows in a listed building is one of the most scrutinised changes you can make to a period home. The windows are among the most visible elements of a building's character, so conservation officers assess each application on its own merits — weighing the significance of the existing windows against the changes you propose.
Our role is to make that process straightforward. We survey the existing windows, document their profiles and sightlines, and produce drawings and a specification that support your listed building consent application. The result is a window that reads as authentic from the street while quietly improving comfort, draught-proofing and warmth.
Because every listed property is different, we never start from a catalogue. We match mouldings, glazing-bar widths, horns and meeting rails to what is already there — or to what historical evidence shows should be there.
Knowing and understanding the rules for your property should always be the first step — and it is where every project with us begins.
What matters
Designed around the rules for your home
Consent comes first
We help you approach your local planning authority with the right information from the outset — survey drawings, profiles and a clear like-for-like specification. Conservation teams assess case by case, and a well-evidenced application is far more likely to gain approval first time.
Glazing is the decisive detail
In historic settings the specification of glazing is often what makes a window acceptable or not. We offer single-glazed, slim double-glazed and vacuum options, hand-finished with a traditional putty line, so the appearance references the existing building precisely.
The right glazing bars for the look
Our 20mm timber-masked glazing bars are our most popular choice — manufactured from matching timber and factory-finished with the window, they replicate the appearance of traditional individual panes while incorporating modern insulated glazing. They give the classic aesthetic of Georgian, Victorian and Edwardian sash windows without compromising performance, and suit both conservation area and heritage projects. For the most stringent listed settings, we also make solid through 'true bars' up to 24mm.
A range matched to your property
Our Historic range is made specifically for listed and conservation properties, with traditional weights and cords and profiles suited to vacuum glazing and authentic glazing bars. Where consent allows, our Classic and Modern ranges offer the same heritage appearance with traditional counterweights or low-maintenance spiral balances.
Authentic profiles, modern performance
Engineered timber resists the twisting and warping of original softwood, while contemporary glazing — even single-glazed units — is warmer and quieter than original glass. Every window is factory spray-finished in your choice of RAL colour, and we colour-match heritage paint brands such as Little Greene and Farrow & Ball, so the finish suits the property exactly. You keep the appearance and gain the comfort.
Specification
The detail, documented
Specification options for listed building windows. Final specification is confirmed at survey and tailored to your property and conservation requirements.
Glazing options
| Single glazed | 6mm toughened glazing. Our Historic range includes a solid through 'true bar' 24mm wide with putty-imitation external beads — for the most stringent listed settings |
|---|---|
| Slim double glazed | 12mm unit (4–4–4, argon, low-E) giving a whole-window U-value of 1.9–2.2; or 14mm unit (4–6–4, argon, low-E) giving 1.6–1.8 |
| Vacuum glazed | 7.8mm high-spec vacuum glazing giving a whole-window U-value of 0.8–1.0 — the slimmest sightline with the highest performance |
| Timber-masked glazing bars (20mm) | Our most popular bar. Slim 20mm bars in matching timber, factory-finished with the window, replicating individual panes while using modern insulated glazing — ideal for Georgian, Victorian and Edwardian properties |
| True glazing bars (up to 24mm) | Solid through 'true bars' up to 24mm wide (not stick-on), with putty-line finish — for the most stringent listed settings |
Timber species
| Engineered redwood pine | With hardwood sill — our most popular option, chosen for stability and value |
|---|---|
| Full hardwood meranti | A durable hardwood throughout |
| Accoya® | Modified timber with exceptional stability and longevity |
| European oak | A premium, characterful hardwood |
| Certification | FSC® certified timber |
Joinery & sash mechanism
| Construction | Traditionally mortise-and-tenon jointed, manufactured to order |
|---|---|
| Modern range | Spiral-balanced mechanism with concealed balances — smooth operation, minimal maintenance |
| Classic range | Traditional weights and cords with steel or lead counterweights, for authentic period operation |
| Historic range | Traditional weights and cords, designed for listed and conservation properties — suitable for vacuum glazing and traditional glazing-bar profiles |
Finish
| Paint system | Factory spray-finished before delivery; microporous system that lets the timber breathe |
|---|---|
| Colours | Single or dual colour, with a wide choice of RAL colours. We can also colour-match heritage brands such as Little Greene and Farrow & Ball |
| Coating warranty | 3 years on the factory-applied paint finish, subject to the recommended maintenance; recoating intervals depend on exposure and location |
Performance & hardware
| Whole-window U-value | From 0.8 W/m²K with vacuum glazing; 1.6–2.2 with slim double glazing, depending on unit |
|---|---|
| Ironmongery | Polished brass, antique brass, polished chrome or satin chrome as standard; other finishes available on request |
Guarantee
| Component | Warranty |
|---|---|
| Timber frame | 8 years |
| Glass & sealed units | 3 years |
| Hardware & ironmongery | 5 years |
| Paint finish | 3 years |
| Conditions | Timber and paint guarantees are subject to the recommended maintenance schedule. Guarantees cover manufacturing defects, not damage, neglect or normal wear. |
How it works
From first survey to aftercare
- 01
Initial quotation
We provide an initial quotation within 1–3 days of your enquiry.
- 02
Site survey
Within 1–2 weeks we measure and document the existing windows on site, recording profiles, sightlines and the property's conservation status.
- 03
Drawings & approval
We produce production drawings and a specification to support your listed building consent application — typically within 1–2 weeks.
- 04
Manufacture
Once your specification and any required consent are approved, each window is crafted to your approved specification. Typical manufacture time is 5–8 weeks; larger projects and bespoke conservation work take 7–12 weeks.
- 05
Installation
Our fitting teams install with minimal disruption — typically 1–5 days depending on project size — working to conservation requirements throughout.
Questions
Listed building windows: your questions answered
Do I need listed building consent to replace windows?
In most cases, yes. Altering or replacing windows in a listed building usually requires listed building consent, even for like-for-like work, because the windows contribute to the building's special interest. We recommend approaching your local planning authority early, and we provide the survey drawings and specification to support your application. This is general guidance, not formal planning advice — your local authority makes the final decision.
Can I have double glazing in a listed building?
Often, yes — but it depends on your property and your conservation officer. Our slim double-glazed units (from a 12mm argon-filled, low-E build-up) and high-spec vacuum glazing achieve whole-window U-values as low as 0.8 W/m²K while keeping true glazing bars and a putty-line finish, so the appearance meets stringent conservation requirements. In the most sensitive cases, single-glazed units with solid 24mm true bars may be specified instead. We advise on the most likely acceptable option for your property.
Will the new windows look like the originals?
That is the aim. We match mouldings, glazing-bar widths, horns, meeting rails and sightlines to the existing windows so the replacements read as authentic. The visible difference is usually improved operation, draught-proofing and warmth — not appearance.
How long does the process take?
As a guide: an initial quotation within 1–3 days, a site survey within 1–2 weeks, and production drawings within 1–2 weeks. Once your specification and any required consent are approved, manufacture takes 5–8 weeks for most projects, or 7–12 weeks for larger or bespoke conservation work. Installation is typically 1–5 days depending on project size. Listed building consent timelines are set separately by your local authority.
Which areas do you cover?
We work across London and the Home Counties, including Surrey, Kent, Essex, Hertfordshire and Buckinghamshire. If your property is listed or in a conservation area, we are happy to discuss it.
Related
Explore further
Discuss your project
Tell us about your property and we’ll advise on the most appropriate, consent-ready specification.
01527 590 776