Weathering the Storm

1. Double-check the storm window's fit (see "Ensuring a Proper Fit" on page 3 of this article) by centering it in the opening and making sure all the screw holes in the fins land on solid wood. Lay a fat bead of butyl or elastomeric caulk on the casing where the storm's fins will be attached. (Do not use silicone, which makes future repairs or replacement more difficult.) Do not caulk the sill.

2. Tip the storm into place and center it from side to side in the opening. Then push it up until its stop hits the bottom edge of the head casing. Drop down about 1/8 inch, so the casing has room to expand with seasonal changes in humidity. Drive the first screw into place at the top fin's center hole.

3. Center the storm's bottom edge and drive two screws into the lowest holes on the side fins, but do not tighten them yet. Drive and tighten the remaining screws around the perimeter. Slide the sash up and down; if they catch, rub, or jam, it's a sign that the frame isn't square. Loosen the side screws, adjust the frame slightly to one side or the other, and try sliding the sash again.

4. Place a straight-tip screwdriver or putty knife at the bend in the bottom sill extender at one side of the storm. Use a hammer to gently tap the extender until it rests against the sill. Repeat on the opposite end.

5. On one side of the storm, drive a screw at an angle into the sill next to the extender so that the screw's head traps the extender's lip. Repeat on the extender's opposite side. Tighten the bottommost screws on the side fins.

6. With the storm secured, raise and lower all the sash one more time to make sure they are operating smoothly. Maintenance on metal storms is minimal. Just wash the glass periodically and make sure the weep holes in the bottom of the frame aren't clogged.