How long do double-glazed windows last — and 4 warning signs your windows might be failing

Double glazing is a smart investment for keeping your home warm, quiet, and energy efficient. But the answer to how long do double glazed windows last depends on a variety of factors. Over time age, exposure to the elements, and general wear and tear can all take their toll, causing seals to weaken, frames to deteriorate, and insulation to become less effective.

While some signs of wear can be repaired, others indicate it’s time to upgrade or replace your windows. The good news is that with the right care, double-glazed windows can last for decades. Whether you have uPVC, timber, or aluminium frames, regular maintenance and early intervention can extend their lifespan – keeping your windows looking and performing their best for years to come.

How long do double-glazed windows last?

"On average you can expect double-glazed windows to last around 25-30 years," explains Paul Higgins, commercial director of Tuffx Glass. "If the window is exposed to extreme weather, you can expect this lifespan to be a bit shorter, at around 20 years."

Paul Higgins

Paul is the Commercial Director at Tuffx Glass, the UK’s leading glass manufacturer and glass processor. He is experienced in purchasing, product development, negotiation, strategic sourcing, and business strategy.

How long do double glazed windows last according to their frame type

The type of window frame you have will impact how long your double glazing lasts, as each material has its own strengths and weaknesses.

Timber Frames

"Timber-framed windows are aesthetically pleasing and offer excellent insulation. With proper care, wooden-framed double glazing can last 30 to 40 years," explains Matt Higgs, managing director at Kloeber. "We only uses engineered timber at Kloeber, which is stronger and more stable than normal timber and due to the multi-coat, microporous paint system, is low maintenance."

“If timber frames are maintained properly with sealing and painting, I think you can make them last longer than uPVC,” adds Paul Higgins. “Treat them regularly with seal and paint. If you don’t, the wood will rot over time.”

Top tip: Inspect the surface coating of your timber frames once a year. If it looks worn or damaged, refresh it with a micro-porous stain or paint to keep the wood protected. Always choose micro-porous finishes, as non-micro-porous options like yacht varnish need frequent stripping and reapplication.

Matt Higgs

Matt is the Managing Director of Klöeber, providing bespoke doors and windows to self builder's and architect's nationwide.

uPVC Frames

"The most common choice in UK homes, uPVC double glazing typically lasts 20 to 25 years depending on quality and wear and tear/upkeep," explains Matt Higgs.

To keep uPVC frames in top condition, Paul Higgins recommends regular cleaning. "If the windows are stained, use a uPVC cleaner or a warm water and white vinegar solution."

Top Tip: You can also lubricate moving parts of your windows, such as hinges, locks, and handles with WD-40 Smart Straw Oil Lubricant from DIY.com to ensure they operate smoothly. This simple step can prevent stiffness and prolong the lifespan of the hardware.

Aluminium Frames

"Known for their sleek design, minimal sightlines and strength, aluminium windows are highly resistant to corrosion and wear. High-quality aluminium double glazing can last 30 to 45 years," explains Matt Higgs. "Kloeber offer thermally broken aluminium frames which reduces heat transfer, improving energy performance."

Paul Higgins suggests cleaning aluminium frames every three months to prevent the buildup of dirt and grime. In coastal or industrial areas, where exposure to salt and pollutants is higher, monthly cleaning is advisable.

Top tip: After cleaning, ensure that the frames are completely dry to prevent corrosion. While aluminium is resistant to rust, prolonged exposure to moisture can cause oxidation over time.

What factors influence how long double-glazing lasts?

Several factors can affect how long double glazing lasts, from the type of frame to the weather conditions it faces. The biggest factors that can shorten its lifespan are harsh weather, poor installation, and lack of maintenance.

The good news is that regular care and professional installation can help your windows last much longer. Paul Higgins highlights the importance of maintenance:

"Keeping the windows clean plays a huge part in reducing any issues. You should inspect them every year to make sure there isn't any damage to the frame or the seal. If there are any signs of damage, make sure they are replaced or repaired as soon as possible."

Four warning signs your double-glazing needs repairing or replacing

If you’ve made it this far and are starting to wonder if your double-glazed windows have seen better days, don’t worry. Matt Higgs shares some key signs to look out for that could mean it’s time for a repair or replacement:

1. Draughts

If you're feeling a cold breeze around your windows – even when they’re closed – this is a tell-tale sign that something isn’t right. Draughts usually mean the seals around the glass or frame have deteriorated, making your home colder and less energy-efficient.

You could try caulking your windows as a short-term fix, but replacing the seals or, in severe cases, the entire window may be necessary.

2. Condensation between the panes

Fogging or condensation trapped inside double glazing is an obvious indicator that your window seal has failed. This type of window condensation occurs when moisture seeps into the space between the panes, reducing the window’s insulating properties. While surface condensation can often be wiped away, internal condensation cannot. At this point, your double-glazing will likely need to be replaced.

3. Excessive outside noise

One of the biggest benefits of double glazing is acoustic insulation, so if outside noise seems louder than before, it could mean the insulating gas within the glazing has degraded and your windows aren’t insulating as well as before.

4. Visible damage to frames

"Warped, damaged, or swollen frames (especially in wooden windows) can lead to functionality issues," says Matt. If paired with draughts or condensation between the panes, it’s a strong sign that your windows need repair or replacement. "Cracks, chips, or yellowing (common in older uPVC windows) are also signs of ageing."

You can often restore timber window sills and frames with sanding, sealing, and a fresh coat of micro-porous paint or stain. However, if the wood is severely rotted or structurally compromised, it’s best to consult a specialist to assess whether repairs or full replacement are needed.

If you think it's time to replace your double-glazing, make sure you do your research. We've put together a helpful guide to new window costs, as well as a double glazing price guide.