How to Seal the Center Seam of a Sliding Patio Door

Select a new seal type for the sliding patio door. Choose a tension seal or fin seal, which are both made up of durable plastic and are highly effective once installed.

Remove the mobile portion of the sliding patio door. Lay it across the tops of two sawhorses with the interior side facing up. Use sawhorses with padded tops or place thick towels over the tops of the sawhorses to cushion the door.

Pry up the small metal staples holding the old weatherstripping in place using a flat-head screwdriver. Use very light to moderate pressure when prying loose the staples to avoid cracking the plastic casing around the door.

Carefully pry up the weatherstripping using a putty knife or other flat implement. Remove any remaining staples as you pry up the weatherstripping. Tap any broken staples lightly with a tack hammer until the broken end is flush with the casing.

Scrape off any adhesive residue using the putty knife. Use very light pressure and hold the putty knife at an oblique angle to keep from gouging or damaging the door. Rub the area where the adhesive was using a cotton ball or rag soaked in rubbing alcohol.

Position the new weatherstripping along the edge of the door that faces the fixed pane. Use the shadow line left by the previous weatherstripping as a guide when orienting the new seal. Mark out the guide holes onto the door casing using a grease pencil.

Create pilot holes with a power drill where you made the marks with the grease pencil. Drive a screw into each pilot hole until the head is flush with the casing. Use the screws provided with the weatherstripping, since they are designed specifically for use on the delicate frames of sliding doors.

Remove the old seal from the fixed portion of the door using a power driver to remove the screws. Pry off the weatherstripping using the putty knife. Do not worry about cleaning the fixed pane as rigorously as the mobile portion.

Affix the new weatherstripping to the fixed portion of the door. Make sure the fin, or plastic flap, is pointed toward the door opening so it will overlap with the new stripping on the mobile portion of the door once it is reinstalled.

Place the mobile portion of the sliding patio door back on its track. Slide the door open to activate the tension seal on the fixed portion of the door. Close the door.