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Common uPVC Window Installation Mistakes

Most uPVC window problems trace back to installation, not the window. Here are the mistakes that cause them.

Why installation decides the outcome

A well-made window fitted badly performs worse than an average window fitted well. The frame must sit true, be fixed securely, and be sealed completely — miss any of those and the window drafts, leaks, or sticks.

What to know

Look for this

  • Frame not seated true or square
  • Under-fixing into the structure
  • Incomplete sealing around the frame
  • Drainage holes blocked or ignored
  • Hardware not adjusted after fitting
  • Skipping reinforcement on large frames

The practical takeaway

This is why we fit with our own team rather than subcontract. Every one of these mistakes is invisible on day one and obvious in a year — and by then the installer's gone.

Questions

Frequently asked

What are the most common uPVC installation mistakes?

Frames not seated true or square, under-fixing into the structure, incomplete sealing, blocked drainage, hardware left unadjusted, and skipped reinforcement on large frames.

How do I know if my window was fitted badly?

Drafts, water ingress, stiff operation, or visible gaps — usually appearing months later rather than immediately.

Why does Glassterr fit its own windows?

Because these mistakes are invisible on day one and obvious in a year. Keeping fitting in-house is how we stay accountable for it.

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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Talk to the maker, not a middleman

Tell us your openings and we'll measure on site, advise, and give you a real quote — factory-direct from our Pannimadai works in Coimbatore.