Sunroom: This room -- also called a solarium or conservatory -- is a glassed-in living space typically attached to the house and accessible from indoors. It is designed to function as additional living area during mild weather but may be too hot or cold in the heart of summer or winter.
Four-season room: Closely related to the sunroom, this option is designed to be heated and cooled. As a result, it can be enjoyed year-round.
Attached greenhouse: Featuring the same basic structure and shell construction as a sunroom or four-season room, an attached greenhouse structure offers light, temperature, and humidity levels that are designed for plants, not humans.
Screen room or porch: This option has walls constructed of mesh rather than glass, which offers the advantage of fresh air without insects. Like the sunroom, it is habitable only when the weather is agreeable. It makes a terrific budgetary choice.
Deciding the optimum location for your room is the first critical step when planning a glass or screen addition. In northern climes, a southern exposure is best because it will receive the most light each day. In the South, however, a southern exposure means additional cooling will be necessary, which could be costly.
An eastern exposure will ease cooling needs by providing sun in the morning and shade the rest of the day -- not so great for after work. A western orientation, on the other hand, will expose you to harsh afternoon sun that will need to be shaded.
A northern exposure will provide lower levels of light and partial shade most of the day. In the North, this can cause the room to be too cool and damp, but it can work fine in the South, where it may eliminate the need for window treatments or additional cooling.
Understanding the components that go into a seasonal room will help you select the type of room you want.
Vinyl is the most popular material for the supports. It costs the least, requires minimal upkeep, and offers the best in overall strength and insulation. It is available mainly in white. Most vinyl supports are "multiwalled," meaning they have an internal reinforcement of either aluminum or galvanized steel.
Aluminum is not as good an insulator as vinyl and is also usually more expensive. However, many rooms that use vinyl-coated vertical supports for aesthetics or added insulation have aluminum as the roof structure for added strength.
Wood is the most expensive choice of structural material, but is also a more appropriate choice for screen rooms, easily allowing you to attach the screen mesh to the timbers. (A screen room needs an extension of the existing roof over the room.) Wood requires periodic maintenance.
Sunrooms, four-season rooms, and greenhouses are walled with glass and roofed with glass or polycarbonate (a tough, transparent thermoplastic). A glass roof is quite a bit more expensive but provides the most clarity. Look for the U-value of the glass or polycarbonate; this is a measure of how much heat the material conducts. The lower the number, the less heat passes through, so choose the lowest possible U value for the most energy efficient space.
Glass walls should be silicone double-sealed, A-rated, and labeled "tempered safety" to meet building code requirements. The best choices are as follows:
Double-glazed glass. This material offers durability, insulation, and glare reduction. A typical U-value ranges from 2 to 2.5. Common glazings, in order of most to least efficient, include clear, solar bronze, and opal.
Double-glazed glass with low-emissivity coating. Applying a "low-E" coating helps the glass reflect heat and ultraviolet rays. The coating reduces the U-value to around 1.7, thus improving energy efficiency.
Double-glazed glass with argon filling and low-E coating. Argon (an inert gas) can be added to further reduce the U-value to about 1.48.
For polycarbonate components, the best options are as follows:
If you are unable to choose the optimum location to control excessive heat loss or gain, or you simply want to extend the hours you can comfortably inhabit your all-season room, consider these options:
Here are estimated costs for a 15-foot by 15-foot room: