Casement WindowsVersatile, Secure & Energy Efficient
At Win-Doors INT LTD, our casement windows offer classic style with modern performance. Side-hung, top-hung, French casement options in uPVC, aluminium & timber. The UK’s most popular window with storm-proof overlap for superior weather sealing.
What is a Casement Window?
A casement window is the most popular window style in the UK. It is defined by its sash overlapping the outer frame – known as a lipped or storm casement – which creates an extra weather seal and superior storm-proofing. The sash is hinged on the side (side-hung) or top (top-hung / awning) and opens outward.
Unlike a flush casement window where the sash sits completely level with the frame for a flat heritage façade, a standard casement’s overlapping lip presses tightly against the frame when closed. This double-seal design makes it the most weathertight, cost-effective and versatile option for British homes.
At Win-Doors INT LTD we offer casement windows in uPVC, aluminium and engineered timber, with configurations including French casement (no centre mullion), fixed + casement combos, and bay & bow casements. All are A-rated, PAS 24 secure and made-to-measure in London.
KeyFeatures
Thermal Break Frame
45mm aluminium + 22mm polyamide barrier stops heat transfer
Multi-Point Locking
3-5 concealed points, Secured by Design certified
Concealed Crank Handle
Smooth stainless crank, 90° outward swing, one-hand
Low-E Double Glazing
24mm double / 36mm triple, Argon filled, warm-edge
100% Full Ventilation
Full sash opening vs 50% slider, maximum cross-breeze
EPDM Triple Seal
Triple compression gaskets, airtight & water-tight
Acoustic Insulation
Up to 38dB reduction, laminated acoustic glass option
Powder-Coat Finish
25yr warranty, teal & gold custom, UV & low maintenance
Two Materials.
One Perfect Fit.
Built for the British climate. Choose low-maintenance warmth or architectural minimalism both Secured by Design and made to measure in the UK.
MOST POPULARuPVC Casement Windows - Profile 22
- A+ Energy Rated
- Multi-point Security
- Zero Maintenance
- 20+ Colours & Dual Colour
- 10 Year Guarantee
- Cost Effective
PREMIUM SLIMLINEAluminium Casement Windows
- Ultra-Slim 54mm Sightlines
- Thermally Broken
- 45+ Year Lifespan
- Powder-Coated RAL Colours
- 100% Recyclable
- Architectural Strength
Windows Built For British Homes, Backed By 20+ Years Of Expertise
We don't just fit windows we manufacture premium casement systems designed for the UK climate, installed with precision, and guaranteed for a decade.
Made to Measure in the UK
Every window manufactured to your exact size, not off-the-shelf. Perfect fit, zero compromise.
Profile 22 System
UK's most trusted 70mm system for thermal & weather performance. Engineered for British weather.
A+ Energy Efficient
Keep heat in, bills down, EPC ratings improved. Argon-filled double glazing as standard.
Secured By Design
Multi-point locking, internal glazing, police-approved security. Your peace of mind built-in.
10 Year Guarantee
Full guarantee on frames, hardware & installation. No quibble, no small print.
Made to Last, Zero Maintenance
Never rots, warps or needs painting. A quick wipe keeps them pristine for decades.
Where Are Casement Windows Used?
From heritage villas to high-performance offices, casement windows adapt to any architecture. Their 90° outward swing, full ventilation, and thermal precision make them the architect's choice for spaces that demand light, air, and control.
01 • ApplicationResidential Homes & Villas
Elevate façades with clean lines and expansive glass. Perfect for modern villas where indoor-outdoor flow matters.
- Floor-to-ceiling ventilation
- Heritage + modern compatibility
02 • ApplicationKitchens & Living Areas
Invite light and cross-breeze where family gathers. Easy crank operation even over counters and sinks.
- One-hand crank operation
- Unblocked view while cooking
03 • ApplicationCommercial & Office Spaces
High-performance thermal break aluminum meets corporate aesthetics and all-day comfort.
- Acoustic insulation up to 38dB
- Low-E for energy compliance
04 • ApplicationBedrooms & Bathrooms
Privacy, ventilation and condensation control. Ideal for intimate spaces needing fresh air without compromise.
- Trickle vents for night cooling
- Frosted & tempered glazing options
05 • ApplicationHotels & Apartments
Durable, secure, and uniform across floors. Multi-point locking meets hospitality-grade maintenance.
- 90° egress for cleaning access
- Consistent sightlines across façade
06 • ApplicationSchools & Institutions
Safe, controllable ventilation for classrooms and labs. Tested for high-cycle daily use.
- Restrictor stays for child safety
- Reinforced hinges for heavy use
Engineered For Every Space
Maximum Ventilation
100% sash opening, 90° outward swing for cross-air flow.
Energy Efficiency
Compression seal + thermal break, U-factor ≤0.28
Unobstructed Views
Slim sightlines, no mid-rail, more daylight
Enhanced Security
Multi-point locking, concealed hinges
Colours to inspire
Aludec and Woodec deliver a step change in the application of PVCu colour finishing options.
Inspired by nature
Woodec
Woodec illustrates the appearance of real wood with a unique character combined with all the advantages of our excellent product range. This is what the new Woodec decorative foils offer. Not only is it difficult to distinguish visually from the natural material, but the Woodec foil also recreates wood very realistically to the touch, thanks in part to deep embossing and a matte top layer.
Inspired by style
Aludec
The attractive surface of Aludec decorative foils, distinguished by a unique fine-grained, matt surface with a similar finish to powder-coated aluminium, is a fabulous option that suits contemporary modern minimalist designs.
The new Aludec foils follow this trend, offered in seven attractive shades ranging from whites and greys, brown, jet black, anthracite, and a metallic finish.
Feature colours
Standard foil colours
All aluplast coloured foil finishes feature innovative technology which improves performance characteristics, providing a much longer life cycle of the surface finish.
Custom foil colours
Our Completed Projects
Flush Casement Windows FAQs
Answers to the questions homeowners ask us most about uPVC, aluminium and heritage flush casements.
What is the casement window?
A casement window is the most popular window style in the UK. It’s a window where the sash overlaps the outer frame (known as a lipped or storm casement) creating an extra weather seal. The sash is hinged on the side (side-hung) or top (top-hung/awning) and opens outward up to 90 degrees for maximum ventilation. Unlike a flush casement which sits level with the frame, a standard casement’s overlapping lip provides superior storm-proofing and is more cost-effective.
What is the difference between a casement window and sash window?
Casement windows are hinged and open outward like a door, offering full 90-degree opening and excellent ventilation. Sash windows slide vertically (box sash) with two sashes moving up and down, common in Georgian and Victorian properties. Casements are more energy-efficient, more secure with multi-point locking, cheaper, and easier to clean. Sash windows are chosen for authentic period aesthetics. We offer both at Win-Doors INT LTD.
Are casement windows energy efficient?
Yes – all our casement windows are A-rated as standard with U-values as low as 1.2 W/m²K double glazed and 0.8 W/m²K triple glazed. The overlapping storm-proof design actually improves weather sealing – the sash presses tight against double Q-Lon gaskets when closed. With warm-edge spacer bars, argon-filled units, and low-E glass, they easily meet Part L Building Regulations and can cut heating bills by up to 25% versus old single-glazed windows.
What is the difference between a casement window and flush casement window?
The key difference is the profile: a standard casement (storm/lipped casement) has a sash that overlaps and sits proud of the outer frame, creating a lipped, storm-proof seal that is excellent for weather performance and is the most popular, cost-effective option. A flush casement sits completely level with the frame for a flat, heritage look and costs 10-15% more. Both can be A-rated and PAS 24 secure. Choose casement for best value, ventilation and weatherproofing; choose flush for authentic heritage flat façade in conservation areas.
How much do casement windows cost in Lodon?
At Win-Doors INT LTD, uPVC casement windows start from £450 per window installed – our most popular and cost-effective option. Aluminium casement windows start from £750 with slim 60mm sightlines and modern powder-coated finishes. Engineered timber casement windows start from £1,100. Pricing depends on size, configuration (side-hung, French, bay), glazing, and colour. All include survey, FENSA installation, and 10-year guarantee. Free quote within 24 hours.
Elevate Your Home with Windows & Doors
Get a free, no-obligation quote for casement windows in London. Made-to-measure, FENSA installed, A-rated & PAS 24 secure. Side-hung, French & bay options in uPVC, aluminium.