How to make your own storm windows

Posted2/6/2021 6:00 AM

Q: My house has double-pane windows, but I still plan to make and add some storm windows myself. How should I build them and are indoor or outdoor storm windows more energy efficient?

A: Since you already have double-pane windows, do-it-yourself storm windows are the most cost effective option. The much higher cost of professionally installed storm windows would likely take a long time to payback from the energy savings.


Storm windows save energy in two ways. First, storm windows, if sealed well, reduce air leakage around your existing windows. Second, they create an additional insulating dead air space over your window. Although it sounds counterintuitive, a narrower air gap between the window glass and the storm is better.

If the air gap is more than 1-inch wide, circular air currents can develop within the air gap and it is no long a dead air space. When this happens, the insulation value of the air in the gap becomes ineffective. The only insulation value increase is from the plastic sheet or film, neither of which is very high.

In general, exterior storm windows that cover the entire window opening provide the greatest efficiency improvement. Even though the air gap may be wider than optimal, they reduce convection losses from the direct force of cold winter winds and reduce air leakage around and through the window. Size them so the frame just covers the wall opening for the best appearance.

The drawback to exterior storms is they must be built much stronger to resist severely stormy weather. The finish on the frame must also be very durable and UV (ultraviolet) light resistant. Making interior storms is much easier and there are do-it-yourself kits available to help making them.

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Using polyolefin shrink film from an indoor storm window kit is effective. Instead of just sticking the film to the existing window frame, make your own separate wooden storm frame. It can be removed each summer and reused for years. This looks much better than just sticking the tape on the window frame.

Make the rectangular storm frame about ¼-inch smaller (room for weatherstripping) than the inside dimensions of the window opening. Paint both sides of the wood frame because the tape sticks better to a painted surface. Cut a piece of the shrink film and stick it to the tape.

Place another strip of tape over the film. Make narrow wood strips and staple them to the back side of the frame over this second strip of tape. This holds the shrink film much tighter when you shrink it with a blow dryer. With just a single piece of tape, the film may come loose and allow air leakage.

An install-it-yourself option, Indow windows, is a frameless acrylic storm window sheet with molded silicone weatherstripping around the edge. It is measured by a visiting salesperson and made to the exact size of the interior window opening. It is shipped to your house, and you just push it into the window opening close to the glass to create a small air gap each winter.


There also are various designs of storm window frame kits available. These often use adhesive-backed, plastic frame material that sticks to the window frame. Cut the frame pieces to fit the window. Cut a sheet of clear acrylic sheet (also blocks fading rays) to fit. Some open and close so the acrylic sheet can be removed during summer or film can be stretched across the framing.

Q: I plan to reside an old farm house and add wall insulation. I like the appearance of real cedar lap siding. What is the best method to nail it up over the insulation and sheathing?

A: Using ring shank nails works well because they grip tightly and should not pop over time. Use galvanized steel or aluminum nails to eliminate rust stains. Drive the nail head in flush with the siding surface.

Locate the nails just above the edge of the piece of siding below so you never end up with nails through two pieces of siding. If you drive the nails up too far on the siding, it has a tendency to split.

• Write to James Dulley at 6906 Royalgreen Drive, Cincinnati, OH 45244 or visit

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