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Signs of a Bad uPVC Window Installation

How do you tell if your uPVC windows were fitted badly? Here are the signs.

The symptoms that give it away

Bad installation rarely announces itself on day one. It shows up over the following months as drafts, damp, stiffness, or gaps that weren't there before.

What to know

Look for this

  • Drafts around the frame edges
  • Water ingress or damp patches
  • Stiff or misaligned operation
  • Visible gaps or uneven sealant
  • Condensation between panes (failed unit)
  • Frame movement or flex

The practical takeaway

If you're seeing these, the window itself is often fine — it's the fitting. Worth knowing before anyone tells you the whole window needs replacing.

Questions

Frequently asked

How do I know if my uPVC windows were fitted badly?

Drafts around the frame, water ingress or damp, stiff operation, visible gaps or uneven sealant, and frame movement — usually appearing months after fitting rather than immediately.

Can bad installation be fixed without new windows?

Often yes — if the window itself is sound, re-seating and re-sealing may resolve it. Worth knowing before someone sells you replacements.

What causes condensation between the panes?

A failed sealed unit — that's the glass unit rather than the fitting, and the unit needs replacing.

From our range

What we make

uPVC Sliding Windows

Multi-track windows that need no swing space.

uPVC Casement Windows

Side-hung sashes for full airflow and the tightest seal.

uPVC Performance Systems

Double-glazed acoustic and thermal windows.

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