Bring your heritage windows and doors into the 21st century
Thermawood Otago can retrofit double glazing into existing heritage wood windows and doors while retaining their original frames, proportions and character. We can also restore timber where required, get old windows operating properly again, source heritage hardware, and work with original leadlight and stained glass.
Many heritage windows were made from old-growth timber that remains in remarkably good condition after a century or more. Where that original timber is sound, there is good reason to keep it. Retaining the existing joinery preserves the proportions and small details that can be difficult to reproduce with something new.
If you have original wooden windows or doors in a heritage home or building, talk to us before deciding they need to come out. Get in touch to arrange a visit and quote for your heritage timber windows and doors.
Retrofit double glazing without changing the original appearance
The Thermawood system was developed specifically for retrofitting double glazing into existing timber windows and doors.
The original frame stays in place while the single glazing is removed and the timber is carefully prepared for the new double-glazed unit. On heritage windows, even details such as the position and angle of the new timber beading are considered so they follow the appearance of the original putty line. The aim is to improve performance without making the window look obviously modernised.
Where timber needs attention before double glazing, restoration can be completed as part of the project.
Retain the details that give your windows their character
It's often the smaller details that make heritage joinery distinctive. Where possible, existing features such as colonial bars and suitable original hardware can be retained and reinstated.
If hardware is worn, damaged or needs replacing, Thermawood Otago can source high-quality heritage hardware to suit the age and style of the joinery. That means you don't have to compromise the appearance of an original window with fittings that look out of place.
Making adjustments as needed on Wood heritage windows and doors
After 100+ years, it's not unusual for timber windows and doors to need a little attention to get them working as they should. Buildings move and settle, frames can shift slightly, layers of paint build up and hardware and moving parts wear over time.
Traditional sash and double-hung windows need extra consideration when they're double glazed because the new glass is heavier than the original single pane. As part of the Thermawood process, sash windows can be reweighted so they continue opening, closing and staying in position as intended. If layers of paint or lack of maintenance have left a sash stuck or difficult to operate, that can be addressed at the same time.
Other styles of opening timber windows and doors can also be adjusted where required to improve their fit and operation. Gaps can be addressed with machined-in draught seals, while worn or damaged hardware can be replaced with heritage hardware sourced to suit the original joinery.
Keep your original leadlights when you double glaze
Your original leadlight or stained-glass windows can be incorporated into your new double glazing, allowing you to improve the performance of the window while keeping the decorative glass that's part of your home or building.
Before any work begins, the leadlights are carefully assessed. Because these panels may be many decades old, their condition can vary considerably. Where required, Thermawood Otago works with an experienced leadlight specialist to determine whether refurbishment or full restoration is needed.
When the work begins, the existing leadlight is carefully removed intact using specialised tools and taken to the leadlight specialist for the agreed work. Once refurbished or restored, your original leadlight is encapsulated between two new panes of glass, protecting it within the new double-glazed unit before it is installed back into your original timber window or door.
What is the difference between refurbishing and full restoration?
Leadlight refurbishment can include cleaning, repairing agreed cracked pieces, replacing the perimeter lead and blackening the new lead.
Full leadlight restoration involves dismantling the panel, retaining the individual pieces of original glass and rebuilding it with new lead and putty. Where glass is broken, replacement pieces are selected to match the original colour and texture as closely as possible.
We'll assess the leadlight as part of the project and explain what is appropriate before work begins. You can read further information about leadlights being retrofitted with double glazing here.
Retrofit double glazing can help reduce heat loss, outside noise and condensation on the glass, while draught seals address the gaps that commonly develop around older timber joinery.
Yes. The glazing can be tailored according to what you need in different parts of the property. For example, one room may benefit from additional noise reduction while another needs greater thermal performance or protection from UV fading. Options such as Low-E glass, argon gas and laminated or acoustic glass can be incorporated where appropriate.
The condition of the timber is assessed as part of the project. Where timber is worn, soft or damaged, Thermawood can refurbish the affected joinery as part of preparing the window for retrofit double glazing. Broken hardware can also be dealt with at this stage.
Yes. Upgrading the glazing gives you the opportunity to consider glass with additional safety and security properties, while worn or broken window hardware can also be replaced as part of the work.
Yes. Retrofit double glazing doesn't necessarily have to be completed throughout the entire property at once. You can prioritise particular rooms or areas and complete other windows at a later stage, which can be useful when you're working to a particular renovation budget. Thermawood specifically notes that projects can be staged in this way.
...great attention to detail to maintain heritage look
"The team from Thermawood recently retrofitted double glazing into our existing frames. The whole house completed in 4 days. Hard working team with great attention to detail to maintain heritage look and feel of home. Windows open and close properly now and no drafts. Very happy with end result."
S Clark