Weatherstripping reduces drafts when it fills the gap without preventing the door from closing and latching. Before buying material, locate the air leak, measure the gap, and distinguish the side/head jamb from the threshold. Material that is too thick can distort closure, while material that is too thin will not seal.
Locate the draft and measure the gap
With the door closed, use side light or a strip of paper to find areas where the seal does not contact. Do not use a flame to locate drafts. Measure several points because a sagging door can have an uneven gap.
Choose a profile for the gap and door movement
Adhesive foam can suit small regular gaps, while rubber or silicone profiles better tolerate frequent movement depending on design. The bottom edge usually needs a sweep or threshold system rather than the same tape used on the jamb.
Clean and dry the surface before adhering
Remove old weatherstripping and residue without damaging paint, clean with a compatible product, and let it dry. Apply tape without stretching it, because it can shrink back and open gaps at corners.
Check closure, latch operation, and egress
Open and close the door several times. It should latch without slamming or excessive force. On an exit door, do not install a seal that makes quick opening difficult. If the slab is badly out of square, correct hinges before trying to compensate entirely with foam.
Sources
- U.S. Department of Energy — Energy Saver — Practical information on home heating, cooling, thermostats, maintenance, and efficiency.