Breaking News Bar
posted: 12/2/2010 12:01 AM

Storm windows a wise choice, not a panacea

Success - Article sent! close

Q. I am considering installing exterior storm windows, but they are expensive. If they will improve energy efficiency very much, I may try to make some myself. What is a good simple window design for me?

A. Installing exterior storm windows can be a wise choice for some homes, but they are not an alternative to replacing old, leaky defective primary windows. You must make sure your existing primary windows are reasonably airtight and in good condition before considering installing storm windows.

Exterior storm windows, because they create a dead space over your primary windows, will increase the insulation value of the entire window opening. Also, storm windows protect your primary window from the ravages of bad weather or ill-directed baseballs. They also can increase the security of your window if you select the proper type of plastic glazing.

There are many designs for making exterior storm windows yourself. The one you select depends upon your woodworking skills and the final appearance you desire. The simplest designs can be as energy efficient as more complex designs, but they just will not look as finished or professional.

The first step is determining the type of clear plastic glazing to use. Glass is heavy and dangerous to work with, so clear acrylic (Plexiglas) is commonly used instead. Acrylic holds up well in the sun and is easy to cut. Although it is tougher than glass, it will crack from a hard impact.

A stronger option is using polycarbonate glazing. This is what is used for bulletproof glass. A baseball should bounce off polycarbonate. It is more expensive than acrylic and it tends to yellow slightly over time.

Another extremely tough material is double-walled, ribbed polycarbonate. You can find it at most home centers. It also provides the highest insulation value from all the dead air spaces between the ribs. Its drawback is its higher cost and the ribs distort the view from indoors.

Measure the exterior window opening about one-half inch out from the existing window. A smaller air gap between the storm window and primary window is more efficient than a wide gap. Window openings are seldom square, so measure the width at top and bottom and the height at each side. Size the storm window frame three-quarter inch smaller than the window opening to leave room for foam weatherstripping to hold it in the opening.

For the simplest construction, use 1-by-2 lumber. It is probably larger than is required for strength, but the larger wood makes it easier to create the corner joints. If you are an experienced woodworker, use smaller lumber for a nicer appearance. Cedar or redwood will hold up the best and looks nice.

Use a simple lap joint, not a weak butt joint, at the frame corners and screw the clear plastic glazing to it. If you have a router, cut a slot for the glazing. This looks better and makes an overall stronger window. If you notice condensation problems, drill several small weep holes through the bottom frame member.

Q. I use a fireplace to help heat my two-story house. I am concerned about safety when I go to bed at night with it still burning. What is a good safety plan to have in case a house fire does start at night?

A. First of all, never go to bed or leave the house when a fire is burning in the fireplace. A good fire safety plan always includes smoke detectors and several routes to exit your house in case of a house fire.

For your second floor bedrooms, install a fire escape ladder. Werner ( offers a complete two-story kit. It mounts securely inside the wall under a window so it is out of the way when not needed.

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