Top Timber Sash Window Companies in London + FAQ

Timber sash windows typically cost between £800 and £2,500 per window depending on size, timber type (softwood, hardwood, or Accoya), glazing specification, and the supplier. A full house with 8–12 windows can range from £8,000 to £25,000+. We offer an online price calculator so you can get an instant ballpark figure before speaking to anyone.

In most cases, like-for-like timber sash window replacement does not require planning permission. It falls under Permitted Development rights. However, if your property is in a conservation area or is a listed building, you should check with your local planning authority. FENSA-registered installers (like us) can self-certify building regulations compliance, which simplifies the process significantly.

A well-maintained timber sash window can last 60–100+ years, depending on the timber type chosen. Accoya windows can last well over 100 years with minimal maintenance. Hardwood (Sapele, Meranti) typically lasts 60–80+ years. Engineered softwood requires more frequent attention but still outlasts PVC by decades. Georgian sash windows from the 1700s still exist in London with their original box frames. The key is periodic maintenance — modern microporous paint systems need recoating every 8–12 years. Compare this to PVC (20–25 years) or aluminium (25–30 years before seal failure).

Accoya is widely considered the best — it's modified pine that is rot-proof, dimensionally stable, and carries a 50-year guarantee. Hardwoods like Sapele and Meranti offer excellent performance at a lower price point. Engineered softwood (redwood) is the most affordable option but requires more frequent maintenance. We use premium hardwood as our standard and offer Accoya as an upgrade.

Yes. Modern slimline double glazing units (typically 12–16mm total thickness) fit into traditional sash profiles without changing the appearance. This achieves U-values of around 1.2–1.4 W/m²K. With Passive Glass technology, we can achieve U-values as low as 0.8 W/m²K — exceeding most new-build window specifications while maintaining traditional proportions. We also offer triple glazing for projects requiring maximum thermal performance — you can explore all glazing options in our 3D Configurator.

Modern timber sash windows with double glazing and draught-proofing are highly energy efficient. They meet and can exceed current Building Regulations Part L requirements. The natural ventilation capability of sash windows (opening top and bottom simultaneously) also reduces the need for mechanical ventilation, contributing to overall building energy performance.

A conservation area is a zone designated by the local council to protect the character and appearance of a neighbourhood. In London, there are over 1,000 conservation areas. If you live in one, you are generally required to maintain the existing character of your property — which usually means timber sash windows. PVC replacements are routinely rejected. Timber double-glazed sash windows that match the original design are almost always approved.

Typically 1–2 windows per day for a full box frame replacement. A standard terraced house with 6–8 windows takes about a week. Production lead time is usually 8–12 weeks from survey to installation. We work neatly, use dust sheets, and clean up at the end of each day.

If the box frame is structurally sound and the sashes aren't warped beyond repair, refurbishment with draught-proofing can be a cost-effective option. If there is significant rot in the frame, failed joints, or you want double glazing, full replacement is usually the better investment. We always assess honestly and will recommend repair when it makes sense — we'd rather keep your money in your pocket than sell you something you don't need.

We provide a 10-year warranty on windows as standard, a 3-year warranty on the paint finish (excluding mechanical damage), and for Accoya timber a 50-year warranty on the wood itself. After installation, every customer receives a written guarantee document. Our warranties are insurance-backed through our FENSA registration. As members of The Joinery Network and part of the Skylon Group, your guarantee is backed by an established business — not a sole trader who might disappear.

Yes. We offer free site surveys within 25 miles of London. We'll measure your windows, assess the condition of existing frames, discuss your requirements, and provide a detailed quote — no obligation, no pressure. You can also get an instant online estimate using our 3D configurator before booking a survey.

Yes — when properly specified. All our windows can be fitted with PAS24 certified security hardware, which is the police-recognised standard for enhanced security. This includes multi-point locking systems, reinforced meeting rails, and the option of laminated safety glass. PAS24 certification is required for new builds and is increasingly requested on renovation projects. Our 3D configurator lets you add PAS24 security as an option and see exactly what hardware is included.

Absolutely. Dual-colour is one of our most popular options. You might want a traditional white or Elephant's Breath on the exterior to match your street, and a darker shade — Railings, Off-Black, or a bold accent colour — on the interior to complement your décor. Every element of the window is painted separately, so the colour split is clean and precise. You can preview dual-colour options in our 3D configurator before committing.

We offer over 55 Farrow & Ball colours, the full RAL colour chart (57+ options grouped by family), and custom colour matching on request. White is our standard finish at no extra cost. Any other colour carries a small surcharge. Our spray finishing system — immersed in preprimer, primed twice, and topped with a finish coat using Sikkens or Teknos products — ensures a flawless, long-lasting result regardless of the colour you choose.

Yes. Listed buildings have stricter requirements than conservation areas — any alterations to the fabric of a listed building require Listed Building Consent from the local authority. We have extensive experience working on Grade I and Grade II listed properties across London. We can replicate original profiles, mouldings, and glazing bar patterns to satisfy heritage officers. Where required, we can produce single-glazed windows for the strictest heritage projects or slim-profile double glazing that is virtually indistinguishable from original glass.

Step 1: Design your windows online using our 3D configurator — choose dimensions, timber, glazing, colour, and ironmongery. Get an instant price estimate. Step 2: Book a free site survey — we visit your property, take precise measurements, and discuss your requirements face to face. Step 3: You receive a detailed quote based on the actual survey measurements. Step 4: Upon acceptance, your windows go into production in our workshop — typically 8–12 weeks. Step 5: Our FENSA-certified team installs your windows with minimal disruption. Step 6: You receive your written guarantee and a FENSA certificate confirming Building Regulations compliance.