Introduction

installing a window tout »
Windows do a lot: help establish a home’s visual character, let in light and air, and frame views from inside. But if not installed correctly, they can become unwelcome avenues for water. "Rot around windows, even in relatively new houses, is one of the biggest problems I see," says This Old House general contractor Tom Silva. "You can't depend on just the trim and the housewrap to stop water."

That's why whenever Tom puts in a window, he makes sure to seal the perimeter of the opening with sticky sheets of self-adhering waterproof membrane, strips of metal flashing, and judicious amounts of caulk. Any rain that gets by one of these layers will be stopped by another.

His final step, once the opening is watertight and the window is set plumb and square, is to plug the gap between the window and the framing with foam insulation.
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