How to Put Nail Fins on a Window

A nail fin is the outer flange lip of a window assembly that lies over the edges of the window opening. Nail fins are made of vinyl and installed around the window frame. Nail fins help facilitate installation on new construction by securing the window frame assembly in the rough opening intended for the window. You can install nail fins on a window frame with the proper tools, materials and basic window construction know-how.

Saw horses
Flat table
Phillips screwdriver
Caulk
Self-tapping screws #8 by 3/8

Instructions

- 1
  Set the window frame on a pair of saw horses or a flat table.
- 2
  Check each corner of the window frame assembly to ensure the mitered joints are secure. Tighten the countersunk corner screws with a Phillips screwdriver if necessary.
- 3
  Apply a thin bead of caulk across the surface of each of the four mitered frame joints.
- 4
  Align a nail fin with one of the mitered joints of the window frame. The leading edge of the nail fin must face the inside of the window frame, or the side of the window facing the interior of the house.
- 5
  Secure the nail fin in place with #8 by 3/8 self-tapping screws. Tighten the screws clockwise using a Phillips screwdriver. The screws are often provided with the nail fins.
- 6
  Repeat Steps 4 and 5 on the remaining nail fins.
- 7
  Attach the 90 degree nail fin corner gaskets. Peel the backing from the gaskets and press each into place on the inside of the four nail fin corners.
- 8
  Check each corner and seal any open areas with caulk. The window is now ready for installation.

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