A screen door can refer to a hinged storm door covering an exterior door or the screened sliding door used on a sliding patio door. In either case, the screen door incorporates screen mesh to keep flying insects from getting in to the living spaces. For the purposes of this description, a screen door will be considered to be the type used on a sliding patio door.
Rollformed aluminum sliding screen doors are the least expensive to produce because they can be manufactured from thin aluminum sheet formed into a relatively strong rectangular shape. Rollformed screen doors have mitered corners into which a steel or aluminum alloy corner is forced using a friction fit. If a steel corner is used, the rollformed sections are often pierced or staked into the corners, to help secure the corners together. If aluminum alloy corners are used, the corner relies on its friction fit alone to hold the door frame together.
In both cases, the weakest point of a rollformed sliding screen door is the corner. After repeated opening and closing, stresses will cause the rollformed shape to loosen in the area of the corner. The door will then stick and jam and typically will require replacement rather than repair.
Extruded aluminum screen doors are made from thicker aluminum than rollformed doors. This makes an extruded aluminum door much stronger but also more expensive. Extruded aluminum screen door frames can be mitered and joined with aluminum alloy corners or can be notched out and joined together with screws that fit in screw holes made as part of the extrusion process.
Extruded aluminum screen doors are generally longer lasting than rollformed screen doors. They are also more easily repaired since, if the corners break, new corners can be inserted without losing the friction fit necessary to hold the door together.
An alternative to aluminum frame screen doors is retractable screen doors which 'disappear' into housing when not in use.