• In this video, This Old House general contractor Tom Silva explains how to install a replacement window.


    1 Pry the interior trim from around the old window.
    2 Cut the sash cords, then lift the sash from the window frame.
    3 Remove any storm sash or screens from the window.
    4 Pull out old window frame from the opening.
    5 Remove the sash weights from inside the wall on each side of the opening.
    6 Fill any voids in the wall with fiberglass insulation.
    7 Squeeze a bead of butyl caulk around window opening.
    8 Apply expanding insulating foam along sill and to underside of expander flashing.
    9 Place the expander on top of the new window.
    10 Set the bottom of the window on sill, then press the top tight to the wall.
    11 Secure window with four 2-inch stainless steel screws.
    12 Apply butyl caulk along the jamb and new window frame.
    13 Install PVC trim around the inside of window.
    14 Caulk around the PVC trim, then nail on the window stops.
    • Difficulty: Moderate to hard
      It takes quite a bit of fussing to pull out the old window and prep the opening, but installing the new window is rather easy
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      Video Directory

      Selected Topic/Section

      Tools List

      • hammer
      • flat prybar
        Flat pry bar
      • utility knife
        Utility knife
      • caulk gun
        Caulking gun
      • brad nailer
        Power nailer
        used to attach PVC window trim; could also use hammer and 2-inch stainless steel finishing nails

      Shopping List

      1. Replacement window

      2. Fiberglass insulation

      3. Butyl caulk

      4. Expanding insulating foam

      5. 2-inch stainless steel screws