How to Install Double-Hung Windows

November 30, 1999

Double-hung windows are a popular choice for many homeowners because of their dual operating sashes, their traditional aesthetics, and they can be simple to install. Always follow the instructions that come with the windows you purchase, and review these general guidelines of how to install double-hung windows:

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  1. Inspect the new window upon delivery, and make sure it will fit into the existing window opening. Ideally the window should be approximately 1/2 inch narrower and shorter than the opening to allow for an easy fit.
  2. Prepare the rough window opening by wrapping the sides and bottom with building wrap, such as Tyvek. It is important to create a barrier allowing water to shed down the sides of the house without running beneath the protective wrap.
  3. Apply a bead of silicone caulk to the wall around the perimeter of the window opening. Ensure that the window's nailing flange will cover the bead of caulk, creating a weather tight seal.
  4. Install the window into the opening and center it on the sill.
  5. Make sure the window is level and plumb, and shim when necessary.
  6. Using 2-inch roofing nails, install the window by setting the nails through the nailing flange at each pre-drilled hole.
  7. From the outside, install self-adhesive flashing tape around all four sides of the window, starting first at the bottom, then the sides, and lastly the top. Again, you are trying to create a weather tight seal which will shed water as it runs down the side of the wall, much like roofing shingle do.
  8. From the inside, insulate the gap between the window frame and the window opening, using a low expanding foam insulation.
  9. Install the interior and exterior trim pieces around the window. The exterior trim pieces should be caulked where they meet the siding and the edges of the window.

Once you learn how to install double-hung windows successfully, you should be able to tackle other home improvement projects with ease.

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