How to Install a Window

By: Scott Gibson, This Old House magazine

Shopping List

Supplies You Will Need

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

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Tools List
Tools You Will Need
- 20-ounce hammer
- 2-foot and 4-foot levels
- Hammer-tacker,
  for stapling builder's felt
- Utility knife
- Measuring tape
- Caulk gun
- Optional: Drill-driver and 1 5/8-inch stainless screws,
  for attaching sill extender to bottom of narrow aluminum sill
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checking the rough opening before installing a window

Photos by: David Carmack

Introduction
Overview
Steps:
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9

1. Check the rough opening

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.