How to reseal a window

Making sure your windows are properly sealed is a must for energy saving and saving on heating bills. Here's a short step-by-step guide on how to reseal windows yourself.

Level of difficulty

Level 1 – Beginner

What you need

• Dust sheet
• Chisel
• Utility knife
• Vacuum cleaner
• Sponge
• Mild detergent
• Mastic
• Caulking gun
• Foam filler

The steps to follow

1. Cover your work area with a dust sheet.
2. Inspect the window surrounding for any cracks or gaps.
3. Scrape away any old filling such as mortar around the window with a chisel or utility knife.
4. Vacuum dust and debris from the window and clean the surface with a mild detergent. Let the window dry.
5. To seal gaps that are less than 5 mm (3/8 in), use non-setting mastic. Select a mastic to match the colour of your window frame or a simple natural colour to blend in nicely.
6. Load the caulking gun with non-setting mastic and hold it at a 45 degree angle on the gap.
7. Unload the mastic and move along the surface until you get to the edge of the window. Smooth the newly applied mastic with your index finger.
8. To reseal gaps that are wider than 5 mm (3/8 in), use a foam filler.
9. Apply the foam filler to the gaps in the same way as you would with non-setting mastic.
10. Let the foam filler dry before opening the window.

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