Timber sash windows are the original — and for most London period properties, still the best — solution for vertical sliding windows. The design has been in use across London’s housing stock for over two hundred years, and the reason it hasn’t been replaced is simple: it works. A well-made timber sash window slides smoothly, seals properly, looks right on a Victorian or Georgian terrace and can last for generations with basic maintenance.
At International Windows Group we manufacture timber sash windows in our own workshop and install them across Greater London. Every window is built to the exact dimensions of your opening, with the profile, glazing bar configuration and finish matched to your property.
See completed installations in our timber windows portfolio or read more on our About Us page.
Why Timber and Not uPVC?
It’s the first question most people ask, and it’s worth answering honestly. uPVC sash windows are cheaper upfront and require less maintenance — for some properties and some budgets, that’s the right answer and we supply them. See our uPVC sash windows page.
But for the majority of London period properties, timber is the better long-term choice for three reasons. First, timber can be repaired — a rotted section can be spliced, a broken sash cord replaced, a failing joint re-glued and re-pinned. uPVC frames cannot be repaired in the same way; when they fail, they’re replaced entirely. Second, timber is the only material permitted in many conservation areas and on listed buildings, where planners require replacements to match originals in profile and material. Third, a properly maintained timber sash window will outlast a uPVC frame by decades.
For a detailed comparison, see our guide to bespoke timber windows in London — before you buy.
Our Timber Sash Windows — What We Offer
Made-to-Measure Replacement Windows
We manufacture new timber sash windows to match your existing profile, sightline width and glazing bar layout. The window is built to the exact dimensions of your opening — not to a standard size that’s then trimmed to fit. Full specification details are on our timber sash windows page, and you can review construction details in our technical drawings.
Double Glazed Timber Sash Windows
Modern slimline double glazing units fit within traditional timber sash frames without significantly altering the sightlines or external appearance. Thermal performance improves substantially. For properties in conservation areas, we advise on specifications acceptable to local planning authorities. Our guide to double vs triple glazing in London covers the real-world performance difference.
Acoustic Timber Sash Windows
For properties near busy roads, railways or under flight paths, acoustic glazing units make a meaningful difference to interior noise levels. We can specify the appropriate unit for your noise environment. Read our guide to acoustic glazing in London for detail on how this works.
Conservation & Heritage Specification
For listed buildings and conservation areas, we produce timber sash windows with slim sightlines, authentic glazing bar profiles and traditional putty or bead glazing details. We provide documentation to support planning applications and have experience working with conservation officers across London boroughs. See our conservation windows and heritage windows pages.
Timber Sash Windows Across London
We install timber sash windows across all London boroughs. Our most active areas include North London, West London, North West London and Central London — wherever London’s Victorian and Georgian housing stock is concentrated.
We’ve put together detailed area guides for the locations where we work most frequently:
Sash windows in North London — Hampstead, Highgate, Islington, Camden, Archway, Finsbury Park and surrounding areas. Includes guidance on conservation area requirements specific to these boroughs.
Bespoke timber sash windows in North London — a more detailed look at the specification process for period properties in North London.
Sash windows in Wembley — restoration and replacement guide for the area’s Edwardian and interwar housing stock.
Wooden windows in Ealing — Bedford Park, Ealing Broadway, Hanwell and the surrounding area.
Outside these areas? Contact us — we cover the full Greater London area.
Victorian & Georgian Sash Windows
The sash windows found across London’s Victorian and Georgian housing stock were built to specific proportions — the ratio of sash height to width, the width of the glazing bars, the depth of the box frame. These proportions matter both aesthetically and in terms of planning compliance for listed and conservation-area properties.
We manufacture windows that respect these proportions. Our profiles are drawn from original examples, and we can match existing glazing bar widths precisely. For more on the history and character of these windows, read our guide to Victorian sash windows in London.
How Much Do Timber Sash Windows Cost?
Cost depends on window size, number of panes, glazing bar configuration, timber species and glazing specification. There’s no honest single-figure answer, but we’ve built a detailed cost guide based on real London projects: How Much Do Timber Sash Windows Cost in London? (2026).
For a quick estimate, use our sash windows cost calculator. For North London pricing specifically, see the North London cost breakdown.
The Process
Free Consultation
We discuss your property, the window style, any planning restrictions and your timeline. No obligation. Arrange yours here.
Precise Measurement
Our team visits to take exact measurements of every opening. Included at no cost with every order. You can review our technical drawings in advance to understand the specification.
Manufacture
Your windows are built in our workshop to the agreed specification — timber species, finish, glazing unit and furniture all confirmed before production starts. Download our product brochures for a full overview of available options.
Professional Installation
Our own teams handle removal of old frames and fitting of new windows. We make good around every opening and leave the site clean. Compliance standards are on our certificates page. Completed work in our portfolio.
Frequently Asked Questions
What timber species do you use?
We work with a range of hardwood and softwood species depending on the application, budget and client preference. Accoya, Meranti and Sapele are commonly used for their durability and stability. We’ll advise on the right choice for your property at the consultation stage.
Can you match my existing windows exactly?
Yes. We take measurements from your existing windows and manufacture to match — including glazing bar width, sash proportions and frame profile. Where we’re replacing only some windows in a property, this matching process is particularly important and we take it seriously.
How long will timber sash windows last?
A well-made and properly maintained timber sash window will last 50 to 80 years or more. The original sash windows in many London Victorian terraces are still in service after 140 years — the ones that have failed have usually done so due to neglect rather than any fundamental problem with the design or material.
Do you offer a warranty?
Yes. We stand behind our work — speak to us at the consultation stage for current warranty terms on manufacture and installation.
Get in Touch
Call us on +44 20 3375 5535 or visit our contact page to arrange a free consultation. We’ll visit your property, assess what’s needed and give you a clear quote — no obligation. You can also download our technical documentation or browse the brochures before we speak.