Thermawood Otago retrofits double glazing into existing timber windows and doors, giving you a warmer, quieter and more comfortable home without replacing good timber joinery.
Retrofit double glazing means replacing the single glass in your existing windows with sealed double-glazed units, while keeping the original window frames in place. It's a straightforward way to upgrade your windows without the cost and disruption of getting all new window frames.
If you're considering double glazing, give Thermawood Otago a call. We can come and take a look and explain what can be achieved with retrofit double glazing. You might be surprised by just how much we can do with the windows you've already got.
Retrofit double glazing with
the Thermawood system
The Thermawood system has been specifically developed to retrofit double glazing into existing timber windows and doors. Your old glass is removed, the timber is carefully prepared and the new double-glazed units are fitted using Thermawood's patented dry-glazing system.
We'll assess the condition of your windows first. If repairs are needed before we retrofit them, we can take care of these through our timber window restoration service.
Why keep your timber windows?
Timber is naturally insulating - its cellular structure contains tiny air pockets that help slow the transfer of heat and cold, while also helping to dampen sound and vibration.
Retrofitting allows you to keep the warmth, appearance and character of your existing timber joinery. You're also keeping a quality building material that's already part of your home rather than removing it simply because the glass needs upgrading.
What types of Wood windows can be retrofit double glazed?
Thermawood Otago can retrofit glazing in a wide range of window styles, including casement, awning, sliding, sash and double-hung windows, bay windows, bi-fold and sliding doors and other timber windows and doors.
We can also work with original leadlight and stained-glass windows for heritage buildings or villas.
Choose the right glass for your home
Double glazing isn't necessarily one-size-fits-all. We'll talk to you about what you'd like to improve and recommend suitable glazing for different areas of your home.
That might mean Low-E glass to improve insulation, acoustic glass to help with outside noise, safety glass where extra protection is needed, or glass that helps reduce UV damage and fading. We can explain the options that are ideal for your home.
The benefits of retrofit double glazing
Upgrading your existing windows with double glazing can make a noticeable difference to the comfort of your home, while allowing you to keep the timber joinery you already have.
- A warmer, more comfortable home – double glazing reduces heat transfer through the glass, helping retain warmth during cold winters.
- Improved energy efficiency – better insulation means less reliance on heating and cooling to maintain a comfortable indoor temperature.
- A quieter home – double glazing helps reduce outside noise, with acoustic glass options available where noise is a particular concern. Many customers say that double glazing reduces traffic noise considerably.
- Protection from UV fading – suitable glazing can help protect flooring, furniture, curtains and other furnishings from UV damage.
- Improved safety and security – laminated and toughened safety glass options are available where additional protection is required.
- Keep your existing timber windows – enjoy the benefits of modern glazing without unnecessarily removing good timber joinery.
- Reduced condensation – double glazing can help reduce condensation on the inside of your windows.
No. Retrofit double glazing can be approached in stages, allowing you to prioritise particular rooms or areas of your home and complete other windows later.
No. We plan the installation so the windows we're working on are completed and secured the same day. Your home won't be left with open window spaces overnight.
In most cases, the retrofit work is completed at your home. However, some windows may need to be taken to our workshop depending on their type, condition and the work required. We’ll assess each window during your initial assessment and explain what will be required before work begins.
This depends on how many windows you're having done and the work each window requires. Thermawood Otago will give you an indication of the expected timeframe when your windows are assessed and quoted.
Yes. Double glazing is heavier than the original single glass, so double-hung sash windows are reweighted once the new glazing is fitted. This allows the sash to remain balanced and continue opening, closing and staying up as it should.
No. Triple glazing is considerably thicker and heavier than double glazing, and the Thermawood retrofit system is designed for double-glazed units within existing timber joinery.
If you're considering triple glazing because you want a warmer or quieter home, talk to us first about what you're trying to achieve. Different double-glazing and glass options can provide very good thermal and acoustic performance without replacing your existing timber windows.
Amazing product, fantastic service, great guys to deal with
"Over the years, we have slowly upgraded our wooden windows to double glazing. They still look beautiful, and the improvement in sound reduction and heat retention has been incredible. We’ve also had the windows replaced in my mother-in-law’s two-storey home, and they look stunning. The service has always been top-notch — consistent, friendly, and professional. Highly recommend."
K Reece
the extra warmth, dryness and quietness inside the house
"We can’t believe how good our new double glazed windows look. The guys at Thermawood are absolute craftsman and the windows are a work of art to look at. We have already noticed the extra warmth, dryness and quietness inside the house. If you’re wondering about whether retro double glazing is worth it, you won’t be disappointed, just go for it! It’s worth every penny!"
Simon Begg