Framing a window is not as difficult as it may seem if you have some DIY knowledge and the right tools. If you are trying to save some money on installation costs, you can install your windows on your own using this simple guide.

Below is a step by step guide for Do-It-Yourself window replacement.

Guide to Framing a Window. 

Follow this guide on how to frame a window:


  1. Remove interior covering of the wall as well as any insulation to expose the studs.
  2. Determine which studs need to be cut or removed and which ones can be used again.
  3. Remember to take note of the sill height and jamb size when taking measurements.
  4. Leave as much of the existing frame as possible. This will help preserve the siding.
  5. Measure starting at the floor and up. Reverse this process. Mark the studs.
  6. Draw straight line using a square on the exposed edge of the studs and the faces.
  7. Using a handsaw, cut as straight as possible.

Install the Framing

  1. Build the header after cutting 2 jacks studs.
  2. Lift into place.
  3. Square up the remaining pieces, using screws to attach the jacks to the stud.
  4. Secure the header to the top using the same technique.
  5. Measure between the studs and cut 2 pieces for the rough sill.
  6. Nail these two pieces together, placing them between the jacks.
  7. Fasten in place.

Cut the Exterior Siding

  1. Once the new framing is in place, in each corner drill a hole from the siding to the outside.
  2. Using a jigsaw, cut out the siding.
  3. Measure and mark each hole along the siding at the width.
  4. Use a long level on these marks to draw a line on all sides of the window frame.
  5. Fasten a straight board along these lines to the siding.
  6. Use this to guide the saw blade. Be careful as you drive the fasteners as you will be covering them with trim moulding upon completion.
  7. Cut along the lines with a sharp blade. Use the holes as your starting point.
  8. Firmly press the base plate against the siding while making an accurate and clean cut.
  9. Move the fence to the other side and cut the top, bottom and side of the frame opening.
  10. Remove the siding.
  11. Install the new window jamb.
  12. If needed, use a circular saw to cut the siding so it butts against the edge of the trim,
  13. Measure the width of the side jamb, using the holes in the siding, to find the inside of the new frame.
  14. After setting some exterior trim molding, draw a line on the outer edge.
  15. Measure the baseplate of your saw to the edge of the plate. Don’t neglect to include the width of the blade.
  16. Measure the same distance using the siding from the trim toward the center of the frame.
  17.  Use this point to set the fence board.
  18. When setting the depth of the saw blade, ensure it will cut through the siding and not the framing.
  19. Cut along all four sides. Remove the siding.

Install the Window

  1. Set the window in place, making sure it is centered.
  2. Level the top and sides.
  3. Leave enough room for expanding insulation foam.
  4. Nail the flange completely around the window.
  5. Add the trim finish.
  6. Add insulation foam.

If you have any further questions on framing a window, please call the experts at WeatherPro Windows and Doors. They will be able to assist you with any concerns. As well, if you prefer professional window installation, they will gladly do the work for you! Call today for a free quote on window replacement!


About Weather Pro – Windows and doors company in Winnipeg, Regina, Saskatoon, Calgary, Edmonton.

Weather Pro Windows & Doors has years of industry experience and our goal is to use our expertise to help each and every client that approaches us, whether a first time buyer or a long-time homeowner, to find the perfect windows and doors that meet all their needs. We specialize in Replacement Windows, Vinyl Windows, Entry Doors, Exterior Doors and Patio Doors. Weather Pro Windows and Doors proudly serves the Winnipeg, Calgary, Edmonton, Regina & Saskatoon areas. Follow us on Facebook!