Double Glazed Timber Windows

Many people assume double glazing means plastic. It does not. Timber windows have carried sealed double glazed units for decades, and today's engineered hardwood frames pair warmth and character with thermal performance that meets building regulations.

This page explains what goes into a double glazed timber window, how the glass differs between a modern house and a listed one, and what it costs to have them made and fitted in the South West.

Frame: engineered hardwood

We specify engineered timber, built up from laminated sections so the grain runs in different directions. That resists the twisting and splitting that plagued solid softwood windows fitted in the nineteen seventies. Engineered European Redwood is our standard choice, with factory applied microporous finishes that let the wood breathe while shedding water.

Glass: two different jobs

On an unlisted house, a timber frame takes the same A rated argon filled units as any modern window, with warm edge spacers to reduce cold edges and condensation. On a listed or conservation area property, slim units of around 14mm overall let glazing bars stay narrow so the window still looks right from the street.

• Standard units for the best thermal figures on modern homes
• Slim heritage units where sightlines matter
• Acoustic or toughened glass on specific openings
• Obscure glass for bathrooms and landings

Cost

Engineered hardwood double glazed casements typically cost around £1,200 to £2,000 per opening fitted, and timber sliding sashes made to measure sit around £1,800 to £3,000. The figures include survey, manufacture, fitting and making good.

Looking after them

Factory finishing gives a long first cycle before redecoration, and after that an inspection and touch up keeps the frame protected. Most timber failures we see come from neglected sills and bottom rails where water sits, not from the timber itself.

Timber double glazing vs uPVC

uPVC is cheaper and needs almost no upkeep. Timber costs more and needs repainting, but it can be repaired, refinished in any colour and will look correct on a period building for generations. Where planning requires timber, the choice is made for you.

Where double glazed timber suits best

Timber is the natural fit for cottages, farmhouses, Victorian and Edwardian houses and barn conversions, where the frames are part of the character of the building. It is also the expected material in many conservation areas and on listed homes. Because timber can be planed, spliced and repainted, a well made frame can be kept going far longer than a plastic one, and it can change colour with the house over the decades. Owners who want the lowest possible maintenance, or who are fitting windows to a rental, usually get better value from uPVC, and we will quote both side by side so the difference in price and upkeep is plain.

Questions people ask