In short: a timber frame insulates better than an aluminium one and suits a character home, while aluminium is stronger, slimmer and needs far less upkeep. Which matters most depends on the house, the size of the openings and how much maintenance you are prepared to do. Here is how the two compare on the things people ask us about.
Warmth
On the frame alone, timber has the edge. Wood is a natural insulator and aluminium conducts heat, and BRANZ's guidance on glazing and glazing units says that timber frames provide better thermal insulation than aluminium ones.
Two things put that in proportion. The first is that the glass is most of the area of a window, so the glazing matters in any frame, and Low E glass is available in ours.
The second is that an aluminium frame can be thermally broken: made in two halves with a strip of insulating material between them, which is how aluminium narrows the gap. We offer thermally broken joinery across the range for anyone who wants it. In practice our standard aluminium joinery is still our biggest seller, and a lot of people decide a thermal break is more than they need. We quote both, so the choice is yours.
Upkeep
Timber is the demanding one. It needs regular repainting, and if the paint is left to fail the timber takes up water and rots. Many of the windows we replace are timber sashes that were lovely once and were not painted in time.
Powder coated aluminium needs washing a few times a year and nothing else. It does not rot, swell, warp or need painting, and our guide to cleaning aluminium windows and doors covers the whole routine. On upkeep, aluminium is well ahead.
Strength and Slim Frames
Aluminium is far stronger for its size than timber, so the frames can be narrower and still carry large, heavy panes of glass. That shows most on big openings: wide sliding and stacker doors, bifolds and tall fixed windows, where a slim aluminium frame leaves more glass and less frame in the view. Timber needs a heavier section to do the same job.
Looks
This one is taste. Timber has a warmth and a detail that suits a villa or a bungalow, and on a heritage house it may be what the council or the street expects. Aluminium is crisp and modern. Ours comes in the full Dulux Duralloy +Plus Solid Range as standard colours, with colours from other ranges available on request and anodised finishes as well, and it can be made to echo the sash layout of an older house where that matters.
Condensation
Neither material settles this one. Condensation is a ventilation issue rather than a window issue, and new windows of any kind still get it. Our guide to condensation on aluminium windows explains where the moisture comes from and what to do about it.
Lifespan and the End of Its Life
Both last decades when they are looked after. Aluminium's advantage is that it tolerates neglect: a frame that has not been washed for years can usually be cleaned and polished back, where neglected timber may be beyond saving. At the end of its life aluminium is recycled, and the old aluminium joinery we remove goes for recycling.
Which Should You Choose?
- Timber if the character of the house depends on it and you are willing to keep up the painting.
- Standard aluminium if you want slim frames, large openings and low upkeep. It is still our biggest seller.
- Thermally broken aluminium if you want the same slim frames with extra insulation in the frame. A lot of people decide it is more than they need, which is why we quote the two side by side.
If you are replacing timber windows and wondering whether aluminium can suit the house, our window replacement page explains how we match the look of the old layout, and the aluminium windows page shows the styles.
Contact Us
Tell us about the house and which rooms matter most, and we will quote standard and thermally broken frames side by side so you can see the difference. Call 09 278 4089 or use the form below for a free measure and quote.
