Dear Jim: My family needs additional living space. I want a sunroom, but I cannot afford to have one built. Are there any do-it-yourself kits available. Can I build one from scratch and what design is best? -Sandi T.

Dear Sandi: Adding a sunroom to a home is an excellent investment and will often increase the resale value of your home more than its cost. Also, it is great recreational area for children. If it gets a little chilly during winter, they won’t mind.

By designing and locating the sunroom properly, it can capture enough free solar heat to stay warm most of the year and help heat the rest of your home during spring and fall. Make it large enough so you can have a small container garden in one corner for fresh green salads and herbs year-round.

Most sunrooms you see on homes are contractor-installed, but not all. The contractors buy the long (20 feet or more) aluminum extrusions and cut them to size. Some sunroom manufacturers will also sell the components to homeowners in precut kit sizes. Do an Internet search and contact sunroom manufacturers to see if they sell their products directly in kit form.

With some of these sunroom kits, you just have to build the base for the sunroom and assemble the components. Some frames are lightweight enough to be built over a wood deck. Often, you will find it less expensive to purchase the glass or plastic window panes locally. SunPorch offers an efficient kit with removable windows to convert to a screened room.

If you are a do-it-yourselfer, you should be able to build an efficient sunroom from scratch. Find a good location on your home that has southern exposure. This provides the most passive solar heating during winter. If you design and build one yourself, to get the most sun, it needn’t be rectangular. An irregular shape may get better sun exposure.

Before you begin to construct the 2-by-4 lumber framing, visit local home centers and building supply outlets. They often have custom-sized, high-efficiency windows that a homeowner or builder did not end up buying. You can purchase these at quite a discount. Once you have your windows, design the rest of the sunroom framing to fit them.

Other than in cold northern climates, you should have a solid roof on the sunroom or it will likely overheat during the summer. Installing roof vents or a venting skylight helps, but shading may also be needed. This increases the costs. Designs with slanted glass will work for moderate climates. In warm climates, always install vertical glass.

For the best comfort and efficiency, add thermal mass to the sunroom. This reduces overheating and helps it hold heat when the sun goes down. A brick paver floor and a concrete block kneewall are effective mass.

Use planters with heavy clay pots. Add an exhaust vent through the house wall to force hot air indoors on sunny winter days.