Flush CasementVersatile, Secure & Energy Efficient
Our flush casement windows deliver timeless heritage style with contemporary performance. Unlike lipped casement with storm-proof overlap, our flush sash sits level with the outer frame for a seamless, authentic flush finish. Available exclusively in low-maintenance uPVC & thermally-broken aluminium, with side-hung, top-hung and French flush configurations. Heritage-approved for conservation areas, with U-values as low as 0.27, multi-point locking and authentic butt-hinge & monkey-tail handle options
Flush Casement Windows Explained
A flush casement window is the heritage choice in the UK. It is defined by its sash sitting completely level with the outer frame known as a flush sash which creates a flat, seamless façade with authentic timber-look proportions.
The sash is hinged on the side (side-hung) or top (top-hung / awning) and opens outward.
Unlike a standard lipped casement window where the sash overlaps the frame for a storm-proof seal, a flush casement’s sash closes flush into the frame. This heritage design delivers a clean, authentic flat finish while maintaining superior weathertightness through triple EPDM compression seals, making it the most authentic, conservation-approved and characterful option for British homes.
At Win-Doors INT LTD we offer flush casement windows in uPVC and thermally-broken aluminium only, with configurations including French flush casement (no centre mullion), fixed + flush combos, and bay & bow flush casements. All are A-rated, PAS 24 secure and made-to-measure in London.
TheFlush Casement Advantage
Heritage flush finish with A-rated efficiency, PAS 24 security and 25-year finish in uPVC & aluminium.
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 Timeless Flush Finish.
Built for the British climate. Choose low-maintenance uPVC for classic warmth, or aluminium for ultra-slim, architectural minimalism. Both Secured by Design and made-to-measure in the UK.
HERITAGE FLUSH CASEMENTuPVC Flush Casement Windows
- A+ Energy Rated
- Multi-point Security
- Zero Maintenance
- 20+ Colours & Dual Colour
- 10 Year Guarantee
- Cost Effective
ALUMINIUM FLUSH CASEMENTAluminium Flush Casement Windows
- Ultra-Slim 54mm Sightlines
- Thermally Broken
- 45+ Year Lifespan
- Powder-Coated RAL Colours
- 100% Recyclable
- Architectural Strength
Built for Britain. Backed by 20+ Years of Flush Craftsmanship.
We don't just fit flush windows. We manufacture premium, UK-made flush casement systems built for British weather, precision-installed and guaranteed for 10 years.
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.
Perfect for HeritageHomes & Modern Builds Alike
From heritage homes to modern offices, our flush casement windows adapt to any architecture. The flush sash design, 90° opening and precision engineering deliver light, ventilation and thermal 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
Designed 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
Customisation at Every Step
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.