A screened-in porch can add value to your home, but it won’t count toward the total square footage at an appraisal or when it comes time to sell. A screened-in porch is not fully enclosed, usable year-round, insulated, or heated or cooled, so it doesn’t meet the requirements of livable square footage in most locations.

The least expensive way to enclose a porch is with screens. These protect the room by preventing insects from entering and, if you live in a warm climate, provide excellent airflow during hot summer months. Screens cost far less than any other alternative, so if you are against getting permits, spending too much, or enclosing your porch in walls or glass, screens are the best choice. 

A sunroom may count toward your home's total square footage or living space if it meets certain conditions, which can vary by local regulations. Generally, for a sunroom to be included, it must be fully enclosed, properly insulated, and equipped with electrical access and a heating and cooling (HVAC) system, similar to a four-season room. It should also meet the same construction standards as the rest of the house. Three-season sunrooms that function more like enclosed porches typically do not count toward the total square footage and are considered exterior living space.

The cost to screen in a porch depends on whether you are adding screens to an existing structure or building a new one from scratch. Adding screens to an existing porch costs about $5 to $7 per square foot, with a national average cost of around $2,800. For example, screening a 12-by-12-foot (144-square-foot) porch would likely cost between $700 and $1,000. If you are building a new screened-in porch, the cost is substantially higher. A new 12-by-12-foot screened-in porch can cost between $6,400 and $18,300, while a new 14-by-16-foot one averages around $11,000. The final price will vary based on the size of the porch, labor costs, and the materials you choose.