You can apply Gluvit™ waterproof epoxy sealer over mildly damp surfaces to fix suspected leaks, but do not apply Gluvit to wet surfaces.
You also don't want to apply Gluvit if rain is in the forecast, because the uncured epoxy sealer will absorb the rain water and turn a milky white color. It will also take a longer time to cure, though it will eventually harden.