average cost of a porch or portico
1 The total cost for a basic 200-square-foot screened-in porch will range from $766 to $1,025 or an average cost of $4.48 per square feet. 2  The cost of materials for a top-of-the-line screened-in porch on an existing deck runs between $860 and $1,070 with an installation cost between $297 and $304.aturally, the cost increases with the desired square feet of the screened-in porch. 1  The cost of materials for a basic 200-square-foot screened-in porch on an existing deck in most urban areas should run between $470 and $680 with an installation cost between $296 and $345.