How to Install Windows

Let there be light and ventilation with these step-by-step instructions.

  1. How To

Cut a hole in your wall and let the sun shine through it with this two-day project.

Materials and Tools:

large and small pry bars
5-in-1 painter’s tool
reciprocating saw
circular saw
folding ruler
carpenter’s square
carpenter’s level
torpedo level
power drill
dusk mask
two 2-by-4-inch boards
power drill
12-inch drill bit
caulking gun
utility knife
rented scaffolding (if needed)
1-by-4-inch boards
roofing nails
window kit
oriented strand board


1. Place the screen from your new window kit against the wall where you want to install the window, and pencil in a rough outline.

2. Cut a hole in the drywall with a circular saw and pry out the drywall. Remove insulation. Remove any metal strapping with a reciprocal saw.

3. Check for existing wiring and install the necessary support without disturbing it.

4. Remove more drywall to create an opening to build a frame. Cut through any unwanted posts with a circular saw, a reciprocating saw and, to make the final cut, a handsaw. Use a hacksaw blade to cut away nails behind posts.


5. Measure and cut 2-by-4’s for the rough sill. Make support by sandwiching two 2-by-4’s together with screws. Pre-drill angled holes through the ends where the new support will attach to existing studs. Fit support into place, check with a level and attach with screws.

6. Continue until you’ve created and installed a header board, side support for the window and cripple studs to tie in the header at the top. Use sandwiched 2-by-4’s for the header, and turn them so the edge faces downward to lessen the chance that the header will bow under weight.

7. Check to see if the window fits the rough opening.


8. Reinforce the frame with more 2-by-4’s. Use a 12-inch drill bit to drill holes from the inside to the outside at each of the corners of your window opening.

9. Outside, use a 2-by-4 as a straightedge and connect the four dots, marking where you’ll need to cut for the window.

10. Set the circular saw so that it cuts through the wall, and cut out the opening. Use the reciprocating saw to cut out the corners.

11. Fit the window in place and mark the siding along the flanges. Set the circular saw just deep enough to cut through the siding and cut the rough opening for the window.


12. Check the window with a level, along the bottom and sides, to make sure it’s both level and plumb. When it is, secure it with roofing nails.


13. Cut new siding pieces and attach them with galvanized nails. Run a bead of caulk along the new siding pieces and the window frame. Trim out the inside.

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