How Long Does Double Glazing Last? Lifespan and Warranties

Quality double glazing is a long-term investment. With good products and proper fitting, you can expect frames to last 25–35 years and sealed glass units to perform for around 15–25 years before any may need replacing.

What affects lifespan

• Fitting quality — a poor installation lets water in and shortens life; this is why the installer matters.
• Exposure — coastal and very exposed sites are harder on seals and finishes.
• Maintenance — occasional cleaning and hinge lubrication go a long way.

Signs of ageing

Misting between panes (a failed sealed unit), stiff or dropped sashes, and draughts are the usual signs — and most are repairable without replacing the whole window.

What to look for in a warranty

Seek an insurance-backed guarantee so cover survives even if the installer ceases trading, and check what’s included (frames, sealed units, hardware) and for how long. A FENSA-registered installer plus an insurance-backed guarantee is the combination to aim for.

Compare installers on guarantee as well as price.

Frequently asked questions

When should sealed units be replaced?

When they mist up internally — the glass can usually be swapped while keeping the frame.

Does a guarantee transfer to a new owner?

Many insurance-backed guarantees are transferable — useful when you sell. Check the terms.