Sensible Home | Building storm windows

Question: I want to make a quick, inexpensive improvement for window efficiency. I thought about making some exterior storm windows myself. They don't have to look great.

What storm-window design do you suggest?

- Ron S.
Answer: Building your own storm windows can offer an excellent payback. This is true even if you already have double-pane thermal glass in your windows. Since a professionally done appearance is not essential, the material cost will be low and the project will require just simple tools and minimal carpentry skills.

People often think exterior storm windows must seal tightly to create an insulating dead-air space. That would be ideal, but just blocking the full force of the wind against your primary windows reduces energy loss. Also, if a tightly sealed dead-air space were created, the storm pane would likely get foggy during cold weather.

When measuring the dimensions of the exterior window's opening to determine the size of storm window you will need, plan on locating the storm window as close as possible to the primary window pane. That will create a smaller air gap between the storm and primary windows and will be more energy-efficient. A large gap can allow air currents to develop within it, which increases heat loss.

The basic design for an exterior storm window is simply a rectangular frame made with standard 1-by-2 lumber. Cedar and redwood are decay- and insect-resistant and look good with just an application of stain, but they are more expensive woods.

Clear acrylic glazing is lightweight, easier to work with, less expensive, and more impact-resistant than glass. Its thickness is not important for efficiency, so select inexpensive thin sheets. For the best durability and impact resistance, select expensive polycarbonate sheets. These may yellow slightly after being exposed to the sun for several years, however.

Plan on making the storm-window frame about one-half-inch smaller than the window opening. That will provide clearance for foam weatherstripping around the outside of the storm frame. The weatherstripping will seal against the window-opening sides and hold the lightweight storm windows in place.

Simple butt-corner joints will be the easiest to cut and assemble for the storm-window frame, but they won't be as strong as mitered corner joints, nor will they look as good. Use an inexpensive miter box or an electric miter saw to make precise 45-degree cuts on the frame ends.

Once you have the frame pieces cut, assemble them with glue and staples. Urethane glue, such as Gorilla Glue, works well and is strong. It foams and expands as it sets, so use it sparingly. Before cutting the acrylic to fit the frame, test-fit the frame in the window opening.

You have two options for installing the clear pane. The simplest is just laying a bead of caulk on the inside edge of the frame. Push the pane into the bead. Run another smooth bead along the other side. A better-looking option is to nail a narrow stop strip inside the frame and have the pane rest against it.

Q: I have a large grassy area to mow at my church. I have always used a gasoline-powered riding mower. Are there advantages to getting a propane-powered mower when this one gives out?

- Johnny D.
A: For riding and walk-behind lawn mowers, propane is a better fuel than gasoline. Using a propane mower costs about 30 percent less at today's prices and produces only a fraction of the emissions gasoline does.

Another advantage of using a propane engine is that it requires very little maintenance and has a longer life than a gasoline engine. The Envirogard ( is a new efficient zero-turn propane mower ideal for large areas.

Send inquiries to James Dulley, The Inquirer, 6906 Royalgreen Drive, Cincinnati, Ohio 45244 or visit

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