white alitherm windows

Alitherm 500 flush casement windows

21st Century windows in a seamless flush style

Alitherm 500 flush casement windows provide all the style of classic windows, with all the advantages of latest-generation aluminium.

Part of our range of premium and luxurious PVCu flush casement windows, Alitherm  500 are seamless, elegant and picture-perfect.  The ideal window to replicate traditional windows and just as effective in a modern home or new extension.

  • Premium, quality aluminium windows
  • Internally beaded for improved security.
  • Excellent thermal performance
  • Traditional or contemporary window handles

Design and Performance

Elegant looks with superb design

Great design with unique looks promises to add real style in your home with excellent energy efficiency and weather protection.

Alitherm 500 flush casement windows come with the latest in profile insulation, combined with our high performance glass for optimum interior comfort and saving you money on your energy bills.

Alitherm 500 flush casement windows in a cream colour and cottage style

Alitherm 500 flush casement windows for traditional homes or new extensions

Available as fixed, side hung or top hung outward opening casements, Alitherm 500 flush casement windows provide all manner of solutions. Perfect for replacing your dated windows or adding the 21st-Century aluminium windows technology in your new extension. The design of this window collection recreates the look of flush timber windows with a flat appearance lining through with the frame.  Uninterrupted lines also provide equal glass and sightline proportions for a neater, better look. Alitherm windows also give you the latest in security and performance thanks to advanced insulation, engineering and product quality.

Made to Measure

Bespoke crafted aluminium windows

Alitherm 500 flush casement windows come made-to-order to your precise designs, sizes and specifications.

Alitherm 500 flush casement windows in modern grey colour to a kitchen
Choose your frame style then select your colour.  Contemporary black or grey, classic white or anything in between. We also provide a different colour inside and out and the latest ultra-modern textured powder-coated finishes. The classic or modern adaptability of these advanced aluminium windows also extends to the hardware. Modern striking window handles in many colours or the traditional styles including monkey-tail, peg stays in pewter and other heritage colours.


High performance aluminium windows

Innovative thermal technology, quality glass and extensive weather protection protect and help insulate your home

alitherm 500 flush casement windows close up detail of bottom of window
These high specification windows deliver the best in thermal efficiency, performance, security and low maintenance. As standard comes a ‘B’ Window Energy Rating,  a U-value of up to 1.4 W/m²K, or upgraded to ‘A+’ with higher performance glass. There's also compliance to British Kitemarks and PAS 24 security credentials. For your new extension, Alitherm 500 flush casement windows meet the requirements of Document L of the Building Regulations too.  Windows come with high security multi-point locking systems, secure locking handles and internal glazing beads, preventing removal of the glass from the outside. A full range of profile styles creates standard bay or bow windows as well as special shapes.

Premium quality materials at affordable prices

The leading aluminium system in the UK

The ideal replacement for your old wood windows or a contemporary look with flexible designs and enormous colour choices.

steel-replacement windows


Alitherm 500 flush casement windows come from one of the UK’s best brands and let you choose the look. Traditional windows come with authentic design features.  Monkey Tail or Bulb End espagnolette handles accessorised with peg stays in black or pewter colours or stainless steel. You can also choose art-deco styles in antique brass, satin nickel or stainless steel. With opening window sizes up to 700mm wide and 1400mm high, enjoy slim frames, more glass and enhanced light into your home. Bay or bow windows, five different window cill options, corner posts and a choice of astragal bars complete the collection.

Case Studies