How to fit / replace windows

Replace your windows by following this guide. If you need to replace the window frame or window sill we've got guides for that too!

Level of difficulty

Level 3: Advanced

What you need

  • A new window
  • Tape measure
  • Utility knife
  • Crowbar
  • Gloves
  • Vacuum cleaner
  • Spirit level
  • Thin pieces of wood
  • Hammer
  • Nails
  • Expanding insulation foam spray

The steps to follow

1. Measure the width of the window frame at the top, middle, and bottom. Take the smallest of these measurements as the width of the new window.
2. Next, measure the height of the window frame at the left, middle, and right. Take the largest of these measurements as the height of the new window.
3. Remove all the fixings (such as curtains, curtain rails and blinds) around the existing window.
4. Use a utility knife to scrape out any old caulk paste or foam around the window.
5. Loosen the outer jamb and sills with a crowbar.

Note:
It might be a good time for you to replace an old window frame or a rotten window sill. If you’re planning to replace the window sill/frame, saw off the jambs of the window frame / sill and lift it off with a crowbar.

6. Remove the window by pulling it out of the window frame opening. You might want to seek assistance when removing the window.
7. Clear the window frame opening of any dust and debris with a vacuum cleaner.
8. With the help of another person, position and fit the new window into the window frame opening.
9. Use a spirit level to check if the window is level. You’ll need to shim the window with thin pieces of wood to level it. Skew nail to secure the shims.
10. Next, secure the window with more nails. Start nailing from the upper left and right jambs of the window and work your way down on both sides.
11. Fix nails on the outside of the window. Nail the window from the upper left and upper right jambs of the window and work your way down on both sides.
12. Spray expanding foam to fill in the holes on the outer window frame.
13. Let the foam set before painting your new window.
 

Please note that all our DIY guides and 'Expert answers' advice have been written strictly for reference only. Rated People do not accept any liability for any damage caused to an individual, property or anything else as a result of following our DIY guides and using our 'Expert answers' advice.