The cost to screen in a porch depends first on what already exists. Adding screens to a sound covered porch is different from constructing a floor, roof and supporting frame. Define that scope before comparing any price per square foot.
Inspect the existing structure
Record the condition of posts, framing, roof, floor and access. Repairs may be needed before a screening system can be installed. Ask whether the proposed components suit the structure and exposure rather than assuming screening corrects structural problems.
Check local approval requirements for the actual work. An existing porch does not automatically mean every alteration is exempt. Keep electrical work, roof changes and structural repairs separate in the estimate so their cost is visible.

Measure screen openings, not only the floor
Floor area helps describe the porch, but screening material follows the wall openings. Measure each opening’s width and height, identify doors and note the framing needed between panels. Two porches with equal floor area may need very different quantities of mesh and framing.
For example, four openings each 5 feet wide and 8 feet high contain 160 square feet of opening area before installation allowances. That does not determine an exact roll order: roll widths, orientation, cutting waste and system instructions still matter.
Screen Tight’s planning guide explains measuring components for its systems. Use a manufacturer’s calculator only with the compatible system and correct measurements.

Build the estimate in separate lines
List mesh, framing or tracks, fasteners, spline or other system components, doors and hardware. Then add installation labor, repairs, access equipment, disposal, delivery, tax and any required approvals. Check which items the contractor already includes so you do not count them twice.
Keep optional upgrades separate. A motorized screen, different door, privacy feature or ceiling fan changes the project, but it should not obscure the cost of basic screening. New roofs and floors belong in a broader construction scope.
Select material for the job
Compare visibility, mesh size, durability, maintenance and any pet-related requirements. Ask for the actual product specification rather than assuming all fiberglass, metal or polyester screens perform identically.
Ordinary insect screening is not a substitute for a required guardrail or a fall-protection barrier. Maintain the building’s required protective features and use qualified advice where the design changes them.
Compare quotes on the same basis
Give contractors the same drawing and requested system. Ask whether their total includes doors, trim, repairs and cleanup, and clarify any allowance that could change after work starts. Record the quote date and how long it remains valid.
Use current local quotes for the final budget instead of an old national average. If you are also repairing the adjoining patio, keep its sealing estimate separate; different trades and materials are involved even when the spaces connect.