Buying guide
Threshold seal or brush strip?
A threshold seal is a raised rubber strip glued to the floor in front of or behind the garage door, so that the door closes onto it. It is the answer to rainwater, leaves and debris coming under the door. A brush-pile strip fixes to the frame and closes the gaps at the sides and the head, where the door does not meet the opening evenly.
Many garages benefit from both: a threshold at the floor, brush along the sides.
Prepare the floor properly
A threshold seal only works if it is stuck to a clean, dry, sound floor. Sweep and scrub the concrete, remove oil and old sealant, and let it dry. Use a suitable outdoor adhesive, press the seal along its whole length and keep traffic away while it cures. Fit it in a dry, mild spell, not in the middle of a wet January.
Measure the door width and the gap
Measure the width of the opening and add a little for the strip's length, and measure the height of the gap under the door at several points because garage floors are rarely level. A taller threshold is needed for bigger gaps and sloping floors. Also check that the door still closes freely over the seal before the adhesive sets.