Clean the area around the gap using a scrubbing sponge and several drops of liquid dish soap to remove any dirt or debris that could interfere with your repair. Let the area fully dry before continuing.
Apply the basecoat of a roof sealer into the gap and the surrounding area with a trowel.
Push a repair fabric into the gap so it presses tightly against the base coat. The cloth is often fiberglass-based and is useful in filling in gaps and stopping leaks.
Spread on a topcoat over the repair fabric. This helps complete the gap-filling process and creates a tight seal with the surface around the repair.