Leaking timber windows can be a nuisance, leading to draughts, water damage and even higher energy bills. The good news is that most leaks can be repaired rather than needing full window replacements. If you’re wondering how do you fix a leaking window, read on for expert advice from our Company Director, Steve Winscott.
How do you fix a leaking window?
Sustainable timber windows are designed to be durable and long-lasting, but like any material, they require maintenance from time to time. Leaking timber windows can often be repaired rather than replaced, depending on the cause of the issue. Here’s what to check and how to fix it:
- Check the seals and joints – Over time, the sealant around the glass (such as putty or silicone) can break down, allowing water to seep in. Reapplying a high-quality, weatherproof sealant can often solve the problem.
- Look for gaps in the frame – Timber expands and contracts naturally, which can cause small gaps to appear between the frame and the surrounding wall. These can be filled with an appropriate wood filler or flexible caulk.
- Inspect the drainage channels – Many timber windows have built-in drainage channels to direct water away. If these are blocked, clearing them out can prevent further issues.
- Repaint or revarnish – If the timber has been exposed to the elements due to worn-out paint or varnish, moisture can penetrate the wood. A fresh coat of microporous paint or wood preservative will add protection – all Nine Zero finishes have a 10-year guarantee.
What causes leaking windows?
Leaks can occur for several reasons, many of which are preventable with regular maintenance. These include:
- Failed glazing seals – The seal between the glass and the frame can degrade over time, particularly with exposure to harsh weather.
- Poor installation – If a window wasn’t fitted correctly, gaps can form around the frame, allowing water to seep through.
- Timber movement – Wood naturally expands and contracts with changes in humidity. If not properly maintained, this movement can create gaps.
- Blocked drainage channels – Many window designs incorporate drainage to prevent water from pooling. If these are blocked by dirt or debris, leaks can occur.
- Wear and tear – Over time, timber frames can develop cracks or splits, especially if they haven’t been regularly maintained and treated with protective coatings.
Which types of windows can be affected?
Leaking can occur in any type of window, but some designs are more susceptible than others:
- Timber casement windows – If the seals around the opening sash deteriorate or if the frame shifts slightly, water can penetrate.
- Timber box sash windows – Traditional box sash windows can develop leaks if the glazing putty wears away or if the frame has not been properly maintained.
- Fixed-pane windows – Even non-opening windows can leak if the glass seal fails or if gaps form around the frame.
How much does it cost to replace a leaking window?
The cost of replacing a leaking window varies greatly and depends on several factors, including size, material, and level of customisation. Here are some ballpark prices to keep in mind:
- Minor repairs (sealing gaps, reapplying putty, repainting): £100-£300
- Replacing glazing in an existing frame: £100-900 dependant on type of glass
- Full window replacement (including frame and glass): £800-£3,000 per window, depending on size and material
While uPVC is often seen as a low-cost option for windows, sustainable timber windows provide better long-term durability, energy efficiency, and aesthetic appeal. All Nine Zero timber is FSC-certified, sustainable and high-performance, ensuring your windows are designed to last for decades with proper care.
Who should you call to help?
If DIY fixes don’t solve your leaking window problem, it’s best to call in a professional.
- Glazing specialists can replace failed glass seals and improve waterproofing.
- Carpenters or joiners can repair damaged timber frames, restoring them rather than replacing them entirely.
- Window manufacturers like Nine Zero can provide expert advice and, if necessary, premium quality replacement timber windows with lead times of 6-8 weeks.
Why timber makes long-term sense
Investing in high-quality, properly fitted timber windows can prevent leaks, improve insulation, lower your carbon footprint and boost the value of your home. Nine Zero’s timber windows and doors are crafted for durability, offering a timeless look while ensuring maximum weather resistance and energy efficiency. If you’re looking for local timber windows, give us a call on 0208 397 8636 and we’ll discuss your needs.