A sliding patio door screen has to fit the track exactly or it will stick, jump off and let insects in. Measuring it correctly is more involved than a window screen.
If your old screen fits, measure it tip-to-tip: width across the frame, then height from the bottom of the bottom rail to the top of the top rail. Note the frame thickness (most patio screen doors use 1" or 1-1/4" aluminium frame) and which side the handle is on (facing in or out).
If the old screen is gone, measure the track and door frame:
- Height: from the inside bottom of the track to the inside top of the upper channel, minus about 1/8" clearance
- Width: between the side channel and the leading edge where the screen meets the fixed panel, minus about 1/16"–1/8"
- Note the roller style (spring-loaded top or bottom), the handle type and which direction it slides
Mesh choice. Standard fiberglass works for light use; metal mesh or pet-resistant mesh is better for high-traffic doors, homes with pets and ground-level units near greenbelt.
Tips. Patio doors are heavy and long — use a metal tape and have a second person hold one end. If the track is worn or the frame is out of square, a custom-built screen can be adjusted to fit, but measure carefully. For a guaranteed fit, book a professional measurement.