How to fix common window problems

Don't worry if something goes wrong with your windows. This article lists a number of common problems and gives you tips on how to fix them.

Broken Windows

To fix a broken window follow the steps below:

  • Put on a pair of protective gloves for safety.

  • Chisel out the old putty that holds the glass in the window frame and remove the remaining glass pieces.

  • Roll the new putty into a sausage shape and press firmly around the frame.

  • Insert the glass and press in some more putty to hold it firmly.

  • Use a wet knife to smooth the putty into place.

  • Leave to dry for at least a week before painting.


There are a number of ways to repair scratches on your double glazed sealed units:

  • Resin

Fill in the scratch with a resin that you can buy at most motor accessory shops or your local DIY store. They may also sell special kits for dealing with window/windscreen scratches.

  • Polish

Polish the scratch out using a clean, lint-free cloth dampened with a very fine abrasive such as Ceria (cerium oxide) or Jeweller's Rouge (iron oxide). Don't use household abrasive cream cleaners as they will scratch the surrounding glass.

  • Replace

If the above options don't work and the scratch is serious then your only remaining option is to replace the entire sealed unit.

Putty Problems

Old putty around timber frames can become dry and brittle, causing draughts, leaks, or even lead to the window falling out. Replacing the putty is a simple process:

  • Soften the old putty with bleach in advance.

  • Carefully chisel out the old putty.

  • Apply the new putty by rolling it into a sausage shape and pressing it around the edges of the glass.

  • Once it is applied you can smooth and shape it with a damp putty knife.


The constant opening and shutting of windows can cause the channels to become bent and distorted. You might be able to fix this issue by measuring the channel against a straight metal rule and tapping any dents out with a hammer up and down the length of a wood block. If this doesn't work and the channel is badly bent, it will need to be replaced by a professional.


If you find condensation within your double glazing panes this indicates that the window seals are broken. If this is the case then there is nothing you can do to fix this problem; your glazing will need to be completely replaced.

If condensation occurs on the inside pane of the window it can cause mould and mildew, eventually leading to rot.

To minimise moisture, install a fan (in a bathroom or kitchen) or dehumidifier to increase ventilation.

Take a look at our double glazing and draught proofing advice for further actions you can take.


Window sills are especially vulnerable to condensation and the elements. Wood can be difficult to restore, so protect the sill by using an aluminium sheet:

  • Cut out a piece of aluminium (using scissors designed for metal cutting) that matches the measurements of your window sill.

  • Position the aluminium piece on top of your window sill.

  • Fix the aluminium into place using 1 inch roofing nails.

  • Tap it into the shape of the sill using a hammer behind a wood block.

  • Secure the aluminium by nailing it underneath the sill and seal the edges with putty.

  • Use a metal primer (bought at most DIY stores) and paint the sill to match the rest of the window.

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