Most people buy windows once every twenty or thirty years. That's why the same mistakes keep repeating. Here are the ones we see most.

Buying windows isn't something you do often. The last time may have been when the house was built, and the market has changed completely since: profiles, glazing, hardware, installation methods. So it's easy to make a choice that looks smart on paper and costs you later.

1. Choosing on price alone

If one quote is much cheaper than the rest, it's worth asking why. The difference is almost always somewhere: in the profile, the glass, the hardware, the installation or the warranty terms. Think of a window as a twenty-year investment, not a number on a quote.

2. Thinking a good window is enough

The best window badly installed will behave like a bad window: draughts, damp around the frame, mould, a sash that sticks. Ask the installer how they fit windows, what they fix the frame with and how they protect the foam. Anyone who does it properly will happily explain.

3. Ordering without an on-site measurement

Walls aren't perfectly straight and openings aren't perfectly square, and a few millimetres can cause trouble during installation. A serious installer won't give a final price without measuring, and that's a good sign, not a waste of time.

4. Not comparing what quotes actually include

Two quotes at a similar price can be completely different. Check whether they include:

  • removal of old windows and disposal;
  • finishing the reveals after installation;
  • drip sills, roller shutters, mosquito nets, if you need them;
  • hardware adjustment and warranty;
  • service when something needs attention.

5. The wrong glass for the wrong room

Not every window needs the same glass. A room on a busy street needs acoustic glass. A glass wall facing south needs Low-E glass to cut overheating. Ground floors and shops need safety glass. Triple glazing isn't always necessary; sometimes good double glazing is plenty. The decision depends on the room, not on what's "best" in the catalogue.

Bonus: leaving the extras for later

Roller shutters, mosquito nets and drip sills are easiest and neatest to fit together with the windows. Adding them later is possible, but usually costs more and is more complicated.