Family Run Business
Made In Britain
Remote Quotation
10 Year Guarantee
Alitherm 400


Combining outstanding value and quality, with class-leading performance and security, the new Alitherm 400 system provides a range of stylish casement windows and single and double doors.

The system is perfect for a wide variety of projects, including both new build and refurbishment, residential and light commercial applications and is proudly made in Britain by Smart. Alitherm 400’s design incorporates Smart’s innovative polyamide thermal break technology, which creates a barrier between the cold air outside and warm air inside, significantly reducing thermal transmittance and enhancing the system’s overall U-value. The system is also fully compliant with changes to Document L of the Building Regulations, is rigorously tested to PAS 24:2016 as standard and exceeds the requirements for weather resistance and security performance.


The Alitherm 400 window is the first thermally broken aluminium system to feature Smart’s pioneering coextruded glazing gasket. This means the beads are supplied with the glazing gasket post-extruded into the profile. This enables the Quick-Glaze beads to be simply tapped in on site, significantly reducing fabrication and installation time.

Available with a flush or chamfered profile, the slim lines of Alitherm 400 provide excellent weather and thermal performance, as well as the security assurance provided by PAS24 accreditation. While the flush, flat face option is suitable for off-set, face-mounted espagnolette locks, the chamfered design features a eurogroove, to enable in-line espagnolette locking mechanisms to be used.

  • Fully compliant with changes to Document L of the building Regulations
  • Smart Quick-Glaze Beads featuring integrated gasket and ‘tap-in’ design for easier fabrication and faster installation

  • PAS 24:2016 Approved – enhanced security for aluminium windows and doors

  • Unrivalled Choice of Colour

  • Suitable for Residential and Light Commercial Properties