How to Cut an Interior Window

Written by jen anderson
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How to Cut an Interior Window
Use a hammer to break through the wall board. (Thomas Northcut/Photodisc/Getty Images)

An added interior window can make any room seem larger and less claustrophobic. You can safely cut an interior window into any non-load-bearing wall. An engineer, contractor or architect can examine your home and tell you which walls are load-bearing and which are not. Once you've determined that the wall you want to cut is not a load-bearing wall, cutting a hole for an interior window is a more straightforward project than you might imagine.

Skill level:
Moderately Challenging

Things you need

  • Window
  • Tape Measure
  • 4-foot level
  • Pencil
  • Utility knife
  • Hammer
  • Reciprocating saw
  • Pry bar
  • Power drill
  • Long drill bit
  • Lumber
  • Table saw
  • 1 1/4-inch drywall screws
  • 3-inch wood screws
  • 1 1/2-inch wood screws
  • 1-foot level
  • Wood shims
  • Trim

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  1. 1

    Check your new window's packaging for the rough opening dimensions, also called RO. This is the size of the hole you will cut in the wall. Mark these measurements on one side of the wall, using a measuring tape and a 4-foot level. Position the top mark about 2 1/2 inches higher than the top of the doors in the room, to line up the finished window.

  2. 2

    Check all four pencil lines on the wall with the level, to make sure the horizontal lines are level and the vertical lines are plumb. Redraw the lines if necessary. Draw a utility knife along the lines, scoring the wallboard.

  3. 3

    Hit the wall inside the scored lines with a hammer, breaking the drywall. Look through the holes created by the hammer into the wall's interior. If plumbing or electrical wires are in the path of the project inside the wall, have a professional move them.

  4. 4

    Cut the wall along the scored lines with a reciprocating saw. Pull out the pieces of drywall with your hands and a pry bar.

  5. 5

    Hold a power drill fitted with a long drill bit at one of the corners of the opening. Drive the drill bit through the wall on the other side of the opening. Be careful to hold the drill level. Repeat this for all four corners of the opening.

  6. 6

    Connect the holes on the uncut wall with a pencil and level. Check the lines for level and plumb as you did on the other side.

  7. 7

    Cut the wall along the lines with a reciprocating saw, cutting through the drywall and the wall studs. Grab the exposed studs through the first opening, and pull out the studs and drywall in one piece.

  8. 8

    Drop your measuring tape inside the opening and measure from the bottom of the wall to the top of the window opening. Cut two pieces of 2-by-4 lumber to that length. Place the pieces of wood on either side of the opening, check with the level that they are plumb, and screw them to the drywall with 1 1/4-inch drywall screws.

  9. 9

    Measure the distance between the two side pieces of wood, and cut two 2-by-4-inch pieces of wood to that length. Attach these pieces to the top and bottom of the opening, driving 3-inch wood screws through the wood into the cut studs. Drive 1 1/2-inch wood screws at a angle through the horizontal pieces of wood into the vertical pieces.

  10. 10

    Hold the reciprocating saw flat against the edge of one of the pieces of wood, and cut away any drywall. making the wall flush with the pieces of wood. Repeat this for all four sides of the opening.

  11. 11

    Lift the window into the opening. Check that the window's sides are level and plumb, using a 1-foot level. Place wood shims under the window, or on the sides as needed to make the window level and plumb.

  12. 12

    Drive 3-inch wood screws through the window jamb and wood shims, into the wood frame surrounding the opening.

  13. 13

    Trim the wood shims by scoring them with a utility knife and breaking them off by hand. Hang trim around the window as you would on any other window.

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