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Energy-efficient and fully weatherproof aluminium casement windows

Fitted with an extended polyamide thermal break, Alitherm windows are an excellent choice for projects requiring an excellent thermal performance. They can achieve U-values of 1.4 W/m²k, far exceeding the minimum requirements of Approved Document L.

With their BS6375-1:2009 accreditation, you’re guaranteed a weathertight installation everytime too, ensuring any properties they’re fitted to remain draught and weather-free.

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Coloured aluminium casements to suit a huge range of projects

We have an extensive selection of bespoke colours and any RAL colour available for the finish, ensuring you can adapt their appearance to meet even the most demanding project requires. You can find a number of popular colour options below, although the full colour range is available via the link here.

  • Specifications
  • Performance
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  • Specifications

    Brand Alitherm
    Material Aluminium Polyamide
    Dual Colour Yes
    Thermally Broken Yes
    NBS Available Yes


    WER Rating B
    U Value 1.4 W/m2K
    Document L Compliant Yes
    Kitemark Yes
    BS 6375-1:2009 Yes


    Side Hung Max Width (mm) 700mm
    Side Hung Max Height (mm) 1400mm
    Top Hung Max Width (mm) 1400mm
    Top Hung Max Height (mm) 1400mm
    Glazing (mm) 24mm & 28mm
    Frame Depth (mm) 59.5mm
    Typical Sightlines (mm) 63.5mm


    Alitherm Frame

    Ultra-stylish, robust & secure

    They boast of a clean, minimalistic look, ensuring for an attractive finish wherever they’re located. And with sightlines of just 63.5mm, they allow huge amounts of natural light to flow inside.

    They are also PAS24:2012 accredited, so they do not compromise on security either. As we have security hardware from security specialists Yale at our disposal, we can also enhance security performance to suit the application.

    Contact us

    Get in touch today for a free quote

    Simply fill out our online quotation form providing your specifications and a member of our team will be in touch with a quote.

    Get a trade quote

    Free Delivery Nationwide

    Our fast and efficient workforce will deliver anywhere in the UK at no extra cost within 10 working days of ordering.


    High Quality Guaranteed

    Our factory is equipped with the latest machinery ensuring high quality performance & maximum productivity, bringing you a swift turnaround at a competitive price.


    Technical Expertise

    As well as manufacturing, our team of technical experts and specialised installers can offer guidance and assistance to meet your needs.

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