Costs to Add a Sunroom

Basic Construction Costs

• In adding any kind of room to a house, homeowners may need to partially tear down a wall to extend the home outward. If working with a sunroom consultant, you can weigh options based on price and aesthetic effect. Unusual exterior walls, such as brickwork, may lend interest. If the sunroom is replacing a porch, the existing flooring structure may be sufficient or it may be necessary to strengthen or replace flooring to maintain area construction code standards. Tiling and wood paneling are common flooring options for sunrooms. Tile and stone floors are particularly effective at absorbing heat, making them more energy-efficient options than wood or carpet. Building a deck with stairs averages about $1,400 and installing new flooring will add another $1,200. Building the structure itself is at least $10,000.

Windows and Glazing

• The primary characteristic of a sunroom is its extensive spread of windows. While sunroom glazing may use glass, plastic or film, glass most effectively "traps" heat energy and does not scratch or yellow over time like other materials do. For an optimally energy-efficient sunroom, double or triple glazing best conserves heat during winter in moderate to cold climates. While glazing may constitute a large share of the total sunroom budget, the energy-saving rewards are tangible. According to Mother Earth News, a 1,200-square-foot house located between 30 and 40 degrees north latitude, with 300 to 600 square feet of glazing, can derive up to 50 percent of its heat from trapped solar heat. During winter, any light reflected off fallen snow only increases this solar intake. A pre-made 8-by-10-foot sunroom structure made with full glass walls will cost around $10,000.

Insulation and Ventilation

• While glazing allows sunlight to enter, proper insulation ensures that heat doesn't escape or diffuse. When the weather is warm, ventilation keeps the sunroom from overheating. The sunroom roof will need to be fully insulated, with fiberglass, foam or granular insulation. Likewise, any full or partial exterior walls must be fully insulated. If the wall dividing the sunroom from the main house is to be newly built, it can be treated as a regular interior wall. Ventilation may be as simple as screened French doors or screened windows. Alternatively, placing vents both high and low in the exterior sunroom walls facilitates "natural convection," with warm air exiting above and cool air entering below. The cost of insulation materials ranges widely, depending on the kind used. As an average, estimate $2 to $3.50 per square foot of space requiring insulation.