Can I replace just the glass unit without changing the whole frame?

Yes — in the large majority of cases. If the frame, hinges and locking gear are sound and it’s only the glass that has misted or failed, you simply replace the sealed unit and keep the existing frame, which is far quicker and more cost-effective than a full window replacement. You’ll need the exact unit sizes and specification so the new unit matches the existing aperture and performance (including any toughened or laminated requirement for that location) – see our comprehensive how to guide on how to change a sealed unit.

The main reasons you’d replace the whole window instead are if the frame itself is damaged, distorted or rotten, if you want to upgrade the frame’s thermal performance, or if the glazing method makes unit removal impractical. Bring your measurements and spec to your local SevenDay depot and the team will confirm the best route.