How to Install a Window Without Fins

The windows you might see displayed in your local home center come in two types -- replacement and new construction. Windows designed for new construction have nailing fins around the perimeter. The fins have nail holes that allow for securing the window to the opening framed in the wall. When replacing a window in an existing building, the use of a replacement window is more feasible because the framing members usually are covered with exterior siding. Replacement windows do not have fins and are installed by driving screws through the window frame and into the wall framing.

Small pry bar
Circular saw (optional)
Scrap lumber (optional)
Finish nails (optional)
Hammer (optional)
Carpenter square
3-inch galvanized wood screws
Power drill
Phillips bit attachment
Caulk
Caulking gun

Instructions

- 1
  Locate the two vertical trim pieces on the inside edges of the existing window frame that secures the bottom sash to the window frame. Pry the pieces away from the window frame with a small pry bar. Remove the trim pieces.
- 2
  Pull the lower sash window frame. Pry out the vertical trim pieces that act as a divider between the upper and lower sashes with a pry bar. Remove the pieces. Pull the upper sash from the window frame.
- 3
  Push the replacement window into the window frame. Ensure the window fits snugly into the frame. Cut filler strips from pieces of scrap lumber with a circular saw if there are gaps between the outer edges of the window and the window frame. Remove the window from the frame and secure the strips to the frame with finishing nails, if applicable.
- 4
  Center the window in the opening. Place a carpenter square on each corner of the window to ensure it is perfectly square. Insert small wood shims where needed between the outer edge of the window and the frame to square up the window, if necessary.
- 5
  Lower the top sash of the replacement window and locate the mounting holes in the vertical edges and top of the frame. Drive 3-inch galvanized wood screws through the mounting holes into the existing window frame with a power drill that has a Phillips bit attachment. Raise the top sash.
- 6
  Raise the lower sash and secure the window to the opening through the mounting holes in the same fashion. Raise and lower both sashes to ensure they operate smoothly.
- 7
  Apply a bead of caulk to the interior and exterior of the perimeter of the replacement window where it meets the existing window frame.

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