Dear Jim: 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.

Dear Ron: Building your own storm windows can offer an excellent payback. This is true even if you already have double-pane thermal glass in your existing windows. Especially if you are not interested in a professional appearance, the material cost is low and it requires just simple tools and minimal carpentry skills.

People often think exterior storm windows must seal tightly to create an insulating dead air space. This 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 opening to determine the size of storm window needed, plan on locating the storm window as close as possible to the primary window pane. This creates a smaller air gap between the storm and primary window and is more efficient. A large air gap can allow air currents to develop within it. These increase heat loss.

A basic simple design of an exterior storm window is just a rectangular frame made with standard 1-by-2 lumber. Cedar and redwood are decay- and insect-resistant and look good with just a 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.

Plan on making the storm window frames about half an inch smaller than the window opening. This provides clearance for foam weatherstripping around the outside of the storm frame. The weatherstripping seals against the window opening sides and holds the lightweight storm windows in place.

Simple butt corner joints are the easiest to cut and assemble, but they are not as strong as mitered corner joints, nor do 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.

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

Dear Johnny: 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 as much emissions as gasoline. Another advantage of using a propane engine is it requires very little maintenance and has a longer life than a gasoline engine. Envirogard (www.onyxsolutions.com) is a new efficient zero-turn propane mower ideal for large areas.

Send inquiries to James Dulley, Bangor Daily News, 6906 Royalgreen Drive, Cincinnati, OH 45244 or visit www.dulley.com.