AJO Aluminium Windows & Doors
Aluminium sash windows on a period-style building
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Aluminium Windows

Aluminium Sliding Sash Windows

Combine the classic proportions of a traditional vertical sliding sash window with the strength, slim sightlines and thermal performance of modern aluminium. Our aluminium sash windows are the ideal choice for period property refurbishments, conservation areas and new builds where a traditional aesthetic is required.

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Vertical sliding

Spring or weight-balanced vertical sliding action — both sashes move independently for flexible ventilation control.

Thermal performance

Thermally broken aluminium profile with argon-filled DGU or TGU — U-values from 1.2 to 0.7 W/m²K.

Secure locking

Secure sash locks and restrictors as standard — meeting current building regulation requirements.

Bespoke sizing

Bespoke to your exact opening dimensions — any RAL colour including heritage shades for period properties.

In situ

Sash windows in different environments

Sash windows on a traditional period property townhouse
Sash windows on a Victorian terrace house exterior in London
Sliding sash window in an elegant interior room

Product overview

Traditional sash aesthetics with modern aluminium performance

Aluminium vertical sliding sash windows replicate the elegant proportions of traditional timber sash windows whilst delivering the superior thermal performance, low maintenance and longevity of thermally broken aluminium. The slim aluminium profiles maintain authentic sightlines without the warping, rotting or repainting associated with timber.

The thermally broken profile system incorporates a polyamide break to reduce cold bridging and condensation. Argon-filled double or triple glazed units achieve U-values as low as 0.7 W/m²K. Spring-balanced or weight-balanced operation ensures smooth, effortless sliding action on both sashes.

All frames are finished in T5 powder coat in any RAL colour — including heritage shades to match existing joinery. Supplied bespoke to your exact dimensions with an 8–10 week lead time. We supply to homeowners, architects, heritage consultants and developers across London, Essex and the South East.

Vertical slidingGlazing barsConservationPeriod propertiesNew buildRefurbishment

Technical Specifications

System typeVertical sliding sash
Frame depth70mm system
Thermal break34mm polyamide
U-value (DGU)1.2 W/m²K
U-value (TGU)0.7 W/m²K
Max sash widthUp to 1200mm
Max frame heightUp to 2400mm
OpeningUpper, lower or both sashes
Standard coloursMetal grey, Black crystal, Coffee, Porcelain black, Silver grey, Sunlight rock black
Custom coloursAny RAL colour available
CE markingEN 14351-1 compliant
Lead time8–10 weeks

Typical applications

Period property refurbishment
Conservation area projects
Listed building works
Residential new build
London townhouses & terraces
Apartments & flats

Aluminium sash window FAQs

Are aluminium sash windows suitable for conservation areas?

Yes. Our aluminium sash windows can be specified with slim sightlines and heritage RAL colours that closely replicate traditional timber sash windows. We recommend consulting your local planning authority, but aluminium sash windows are increasingly accepted in conservation areas across London and Essex.

How do aluminium sash windows compare to timber?

Aluminium sash windows offer the same elegant proportions as timber but with significantly better thermal performance, zero maintenance requirements and a much longer service life. They will not warp, rot, swell or require repainting.

Can aluminium sash windows be double or triple glazed?

Yes. Both double glazed (DGU, U-value 1.2 W/m²K) and triple glazed (TGU, U-value 0.7 W/m²K) options are available. Triple glazing is particularly popular for properties in noisy urban areas such as London.

What is the lead time for aluminium sash windows?

8–10 weeks from order confirmation. We provide CAD design drawings for approval before manufacture.

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