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, just follow the steps below:

  1. Put on a pair of protective gloves for safety.
  2. Chisel out the old putty that holds the glass in the window frame and remove the remaining glass pieces.
  3. Roll the new putty into a sausage shape and press firmly around the frame.
  4. Insert the glass and press in some more putty to hold it firmly.
  5. Use a wet knife to smooth the putty into place.
  6. Leave to dry for at least a week before painting.


There are a number of ways to fix 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 good 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:

  1. Soften the old putty with bleach in advance.
  2. Carefully chisel out the old putty.
  3. Apply the new putty by rolling it into a sausage shape and pressing it around the edges of the glass.
  4. 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.


Condensation is a problem if it occurs within the double glazing panes as 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, which can cause the appearance of rot in the wood. Wood can be difficult to restore, so protect the sill by using an aluminium sheet:

  1. Cut out a piece of aluminium (using scissors designed for metal cutting) that matches the measurements of your window sill.
  2. Position the aluminium piece on top of your window sill.
  3. Fix the aluminum into place using one inch roofing nails.
  4. Tap it into the shape of the sill using a hammer behind a wood block.
  5. Secure the aluminium by nailing it underneath the sill and seal the edges with putty.
  6. Use a metal primer (bought at most DIY stores) and paint the sill to match the rest of the window.

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We try to make the advice on our website ( as useful and reliable as possible. However, the purpose of this advice section of the website is to provide homeowners and private landlords with general guidance and useful tips only. It doesn't necessarily deal with every important topic or cover every aspect of the topics with which it deals and might not be relevant or appropriate in all circumstances. It is not designed to provide professional advice or financial advice and should not be relied on as such. Click here to read the disclaimer in full.