Close the door on a strip of paper and gently pull it out. Compare the resistance at several points to locate spots worth examining for worn or uneven weatherstripping.
Map the frame
Cut three identical strips from scrap paper. Starting at the top, trap one strip between the door and frame where the weatherstripping contacts the door. Shut and latch the door normally. Pull gently and note whether the strip holds firmly, slides with light resistance or slips out freely. Repeat along the latch side. Keep hands clear of closing edges and record the positions on a sketch.
Compare like with like
If the upper latch side holds and the lower latch side releases easily, open the door and look for a flattened seal, dirt or a visible gap at the lower position. Use a new strip if the old one tears. The result is a comparison of contact pressure. It gives you a place to inspect, while air movement depends on conditions and the rest of the doorway.
Check your sketch
Choose one loose location and one firm location. Repeat each measurement twice using the same paper. Does the same pattern show up? Consult the Department of Energy guide when matching a weatherstripping material to the type of joint.
