Duotherm Composite Windows

The industry’s best kept secret!

For many years Smarts have supplied the industry with Duotherm profiles market and for many years we’ve manufactured the Duotherm range of windows (and doors) for projects where people have required the benefits of strong slim aluminium profiles outside and warm contoured PVC-U profiles on the inside – the best of both worlds!
We’ve often found Duotherm to be the ideal solution for people who love the look and proportions of a traditional moulded timber window but are put off by the maintenance and performance issues that go with wood.




  • Duotherm is ideal for dual colour applications where white internal finish is required.  The external aluminium profiles can be painted any standard RAL and British Standard paint finish as well as being available in silver anodised finish.
  • The Duotherm ‘Elite’range of main profiles feature full ovolo mouldings typically found on traditional timber windows and with a 70mm frame depth are an ideal replacement for softwood or hardwood windows.




  • The full range of profiles caters for all styles of fixed lights and casement windows including stone mullion replacement windows with 51mm equal or odd leg frames giving very slim sightlines.
  • Duotherm windows and doors  are also available in either light oak or full mahogany woodgrain finish either both sides of profiles or woodgrain out / white PVC-U in.


light oak wood grain

A Full range of Duotherm single and double doors is also available