Misted or Condensation Inside Double Glazing: Causes and Fixes

Condensation between the panes — misting you can’t wipe away — means the sealed unit has failed and lost its airtight seal. The good news: you usually don’t need a whole new window.

Why it happens

Over time the perimeter seal of a sealed unit can degrade, letting moist air in. The desiccant that keeps the cavity dry becomes saturated and moisture condenses on the inner glass.

Can it be fixed?

In most cases a repair specialist can replace just the sealed unit (the glass) while keeping your existing frame — far cheaper and quicker than a new window. If the frame or hardware is also failing, replacement may be the better long-term call.

Condensation on the inside or outside

• Inside the room (wipeable) — usually a ventilation/humidity issue, not a window fault; trickle vents and extractor use help.
• Outside on cold mornings — actually a sign of good insulation; it clears as the day warms.
• Between the panes — failed unit; replace the glass.

Get a quote for sealed-unit replacement or advice.

Frequently asked questions

How much to replace a misted unit?

Far less than a new window — it’s a glass-only swap in most cases. Get a couple of local quotes.

Will it happen again?

A quality replacement unit with a good seal should last many years; warranties typically cover premature failure.