Consider a kit when building a sunroom

Q. We think adding a sunroom would give us more space and assist with winter heating our house. What design factors should we consider when building one from a kit or from scratch?

A. Adding a sunroom can be a good investment by providing more living space at a reasonable price. This is particularly true if you build a kit yourself or one from scratch. It still will be a substantial investment so design it properly.

For the average do-it-yourselfer, it is wise to purchase a sunroom kit and follow their construction instructions precisely. Before selecting a kit, make certain it is designed for do-it-yourself construction and obtain a list of recommended power tools. Building one can be a more difficult project than it first appears.

When comparing the various sunroom kits, ask about how much comes preassembled, particularly the windows, roof panels, skylights and doors. I built a kit at my home and many of the structural aluminum members were delivered in long lengths. They had to be carefully measured, mitered and cut to length.

Determine your priority of extra living space vs. capturing heat for your house. A sunroom can do both to some extent, but if you primarily desire one or the other, it must be designed with that purpose in mind. Also, a sunroom designed for winter heating may tend to overheat and be uncomfortable during summer.

The sunroom location and its orientation to the sun is a primary factor. In order to have any chance of capturing solar heating for your house, it must be on the south or southwest side of your house. If your only location is the east or the north side, forget about using it for heating. It will likely require supplemental heating to be usable during winter.

Other key factors to consider for sunroom used for heating are adequate solar thermal mass and a way to move the extra heat into your house. Thermal mass can come from stone or brick sides or flooring and often barrels filled with water. Without adequate thermal mass, the sunroom will quickly overheat in the afternoon and quickly cool off in the evening.

Add two groups of fans. One group is used to force the solar heated air into the house during winter. The other group, spaced near the roof, is used to ventilate the excess heat during summer. If the entire side of sunroom is open to inside the house, heated air will circulate in naturally. I prefer installing sliding glass doors between the house and sunroom.

Knowing the planning basics, building one yourself using standard lumber is the lowest cost option. It also provides more design flexibility to meet your specific needs and house. You may even decide to create an atypical, unique design that is not rectangular.

As with most projects, select dimensions in 4 feet and 8 feet sizes to better utilize standard lumber and material sizes. Also, before starting the project, visit local window installers and builder suppliers. They may have large windows, which someone has returned, at a significant price discount.

For year-round use and to gain heat from the sunroom, use double- or triple-pane windows. If, due to poor sun orientation or other factors, you realize you cannot use the sunroom for solar heating, lower-cost single-pane windows are fine. This will create a three-season (spring, summer, fall only) sunroom.

A lean-to design with a sloped front is the simplest to build and captures more solar heat. This design also uses less lumber and roofing materials, but it is more difficult to ventilate and to add shading. There may be an overheating problem during summer.

Q. We have a wood-burning fireplace that we seldom use because it does not draw well and the room smells smoky. The chimney has a smoke shelf. Does that help or just impede the smoke path?

A. The purpose of a smoke shelf is to improve the draft of the fireplace so that your room does not get smoky. Basically, cool outdoor air flows down the chimney, hits the smoke shelf, mixes with the warm smoky air and flows back up and out. This draws out the smoke.

Make sure there is adequate combustion air for the fireplace by opening a window slightly. Also, the draft will be stronger on very cold days.

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