Bespoke Timber Casement Windows

Timber Casement Windows

Casement windows are the most versatile window type in British architecture. The sash is hinged at the side and swings outward (or inward), providing excellent ventilation and unobstructed views when open. At Prime Sash Windows, we manufacture bespoke timber casement windows in flush casement and stormproof designs — built to your exact dimensions from engineered hardwood.

Based in London? Our casement windows London page covers conservation areas, typical London house types and local installation. For prices by size, use the casement window price calculator; to compare with sash, read sash vs casement windows.

Casement windows suit a wide range of property styles, from Arts and Crafts cottages and 1930s semis to modern new-builds and extensions. They are also the go-to choice where sash windows are not appropriate — for instance, in properties where the original windows were casements, or where wider openings are needed.

Flush Casement vs Stormproof

• Flush casement — the sash sits flush with the outer frame when closed. Clean, minimal sightlines. The traditional choice for period properties, cottages, and Conservation Areas. Often required by planning officers as the historically correct design.
• Stormproof casement — the sash overlaps the outer frame, creating a deeper weatherseal. Slightly more robust against driving rain. Common on 1930s–1960s properties and modern builds.

Both types are available in our 3D configurator. Choose side-hung, top-hung (awning), or fixed panes in any combination.

Specification

• Timber — engineered Accoya (50-year guarantee) or premium hardwood.
• Glazing — double glazed 4/16/4 (U-value 1.4) or triple glazed (U-value 0.8). Part L compliant.
• Security — PAS24 multi-point espagnolette locking. Secured by Design option.
• Opening — side-hung, top-hung, or fixed. Multi-pane configurations available.
• Colour — any of 2,000+ RAL colours, full Farrow & Ball range. Dual colour available.
• Hardware — monkey tail, pear drop, or contemporary handles. Friction stays or traditional stays.
• Finish — factory spray-finished with Sikkens coatings.
• FENSA registered — Building Regulations self-certification on completion.

Guide Pricing

Prices include double glazing, white finish, and standard hardware. Use our 3D configurator for an exact quote.

Casement Windows for Every Property

Timber casement windows have been used in British homes since the medieval period. The flush casement design, with its clean face and minimal frame, is the historically correct window for cottages, farmhouses, Arts and Crafts properties, and many rural conservation areas. Stormproof casements became standard from the 1930s onward and remain the default for modern domestic construction.

Both designs accept glazing bars — cottage bars (horizontal only), Georgian bars (grid pattern), or plain glass. We also manufacture shaped casements with arched, gothic, or segmental heads for feature windows.

How It Works

• 1. Design online — Use our 3D configurator to design and price your casement windows.
• 2. Free survey — We visit your property, measure precisely, and confirm the specification.
• 3. Manufacture — Built in our workshop. Typical lead time 6–8 weeks.
• 4. Installation — FENSA-certified fitting team. Minimal disruption.

Frequently Asked Questions

Flush casement or stormproof casement?

Flush casements sit level with the frame and suit period and conservation-area properties; stormproof casements overlap the frame for extra weather protection and suit most later houses. We make both; our comparison guide explains the difference.

How much does a timber casement window cost?

Guide prices start at about £610 for a 1000 × 1200 mm single opening casement (supply only, excluding VAT and installation; standard specification from our online configurator, October 2026). The first square metre is £500 and each further square metre £300, plus mullions, transoms and opening sashes. The casement price calculator gives the figure for your layout.

How many casement layouts can you make?

20 standard layouts, from a single light to multi-light windows with fanlights and transoms, each with its own bar pattern and hinge side, plus custom middle-section widths.

Can I design a casement window online?

Yes. The online configurator shows the window in 3D with the chosen layout, opening sashes, bars, colours and glazing, and updates the price as you change it.

Areas We Cover

We manufacture and install bespoke timber casement windows across London, Hertfordshire, and the Home Counties. Free site surveys within 25 miles of London. We also deliver nationwide for supply-only orders. See our casement windows London page for London-specific information.