Step 1: Check the rough opening

checking the rough opening before installing a window
Photos by: David Carmack
«»
Measure the width of the rough opening at the top, middle, and bottom and the height at both sides and in the middle.

If the difference between the three width measurements or the three height measurements of the rough opening is more than 1 inch, cut tapered filler strips from stud stock and nail them to the sides of the opening that are out of level or out of plumb.

Make sure the outside dimensions of the window are at least ¾-inch narrower and ½-inch shorter than the smallest width and height measurements, respectively. If they're not, you'll have to either reframe the opening or order a new window.

Ask TOH users about Windows

Contribute to This Story Below

    Tools List

    • hammer
      20-ounce hammer
    • two-foot level
      2-foot and 4-foot levels
    • tacker hammer
      Hammer-tacker,
      for stapling builder's felt
    • utility knife
      Utility knife
    • 16-foot tape measure
      Measuring tape
    • caulk gun
      Caulk gun
    • drill
      Optional: Drill-driver and 1 5/8-inch stainless screws,
      for attaching sill extender to bottom of narrow aluminum sill

    Shopping List

    1. WINDOW

    2. CAULK

    3. MINIMIALLY-EXPANDING FOAM INSULATION

    4. 15-POUND BUILDER'S FELT

    an alternative to membrane for flashing the rough opening



    5. WATERPROOF MEMBRANE

    6. METAL FLASHING

    7. FOAM INSULATION

    8. 1 1/2-INCH ROOFING NAILS

    for fastening nailing fins to the sheathing