Choosing between bay and bow windows for energy-efficient home upgrades

Q: I have an old picture window I want to replace with a bay or bow window. My budget is tight. Which type is best and most efficient? Should I buy an entire unit or assemble one from individual windows?

A: Those old large single-pane picture windows, which were common in house built many years ago, are extremely inefficient (overall only R-0.5 insulation at best). Not only is there a huge heat loss (gain in summer) through the glass, there also likely is no insulation around the frame inside the walls. If it faces west, count on drapes, furniture and carpeting being badly faded.

A bow or bay window is sometimes called the “poor man's sunroom.” One can provide some of the benefits of a sunroom at a lower cost. These include making your room appear larger, providing a seat under glass at the window and a good location for plants. Even though it costs much less than a small sunroom, having an efficient bow or bay window installed is not inexpensive.

The basic difference between a bow and a bay window is number of panels. A bow window is made of four or more narrow window panels, often of the same width. Five windows is the most common configuration. Using more window panels creates a more circular appearance which many people find attractive. To minimize the cost, have only the windows on each end operable. This configuration provides adequate natural ventilation with having only the ends open.

Bay windows are made from just three window panels. The two angled side panels usually can be opened and are angled at either 30 or 45 degrees. The fixed center window is similar to a smaller picture window with an unobstructed view of the outdoors. To better simulate a sunroom, a 45-degree bay window extends out further than a 30-degree window from the house wall. This provides more space for plants or a bench seat.

When replacing a large picture window, 10 feet wide or larger, with a bay window, a 30-degree design is your best choice. It will provide plenty of openness and area for plants, but will not extend out too far. A large triple-pane center window is quite heavy to be cantilevered out far from the wall.

There is not a significant difference in the energy efficiency or durability of a bow or bay window. A bay window, particularly a 30-degree design, may be slightly more efficient because there are fewer joints and seams to be sealed between the window panels. Also, wherever there is framing material and supporting lumber in the wall, there is less room for insulation. Some of the new designs of insulated window glass are as efficient as some existing older house walls.

As with any replacement window style, glass is the heart of the window. Select the most energy efficient glass your budget will allow even if it forces you to cut back on the styling or trim options. Triple-pane glass is best, but at the very minimum, select double-pane glass with a low-emissivity coating and inert gas. Make sure to select the proper glass for your area because the location of the low-emissivity coating varies depending upon your climate. All the new glass types will reduce fading.

Since a bow or bay window protrudes from the wall, it is ideal for natural ventilation during summer to reduce your air-conditioning costs. Select casement window style for the side or end windows. Double-hung windows, which generally do not provide good natural ventilation, are also acceptable on a 45-degree bay window because they protrude out enough from the wall to catch gentle breezes.

In addition to high-quality glass, look for a bow or bay window which has thick insulation in the seatboard and the top. When building your own bow or bay window, use a minimum of one-inch polyurethane rigid foam. This saves energy and improves your comfort near the window. Your plants will also appreciate it during the winter.

Unless you are very handy with tools, it is generally better to purchase an entire unit designed as a bow or bay window. This will cost more than assembling one from scratch with individual windows, but it will likely be stronger and more airtight. When designing and building your own, also consider installing cable supports from above for one that extends out very far from the wall.

The following companies offer bow and bay windows: Andersen, (800) 426-4621, www.andersenwindows.com; Champion Windows, (877) 424-2674, www.championwindow.com; Jeld-Wen, (800) 535-3936, www.jeld-wen.com; and Weathershield Windows, (800) 222-2995, www.weathershield.com.

Q: I treated my wood deck with a sealer last fall to protect it from the weather. This spring, the sealer is peeling off all the horizontal surfaces. What did I do wrong and how can I fix it?

A: Your problem is not uncommon, particularly when a heavy surface sealer is used. The most likely cause of the peeling is you did not adequately clean the deck surface and you used a sealer which coats the surface instead of penetrating into it.

Use a pressure washer on medium pressure setting to clean off the peeling sealer. Use a decking cleaner, such as an oxygen-based bleach/cleaner, to further clean the surface. Apply a wood brightener treatment. Finish it with a penetrating sealer withChoosing Between Bay and Bow Windows for Energy-Efficient Home Upgrades micro particles to block UV damage.

• Send questions to James Dulley, Daily Herald, 6906 Royalgreen Drive, Cincinnati, OH 45244 or visit www.dulley.com.

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