Roofing in El Rancho Verde, Rialto

Straight away if the water is near anything electrical, the ceiling sags, or the leak gets faster as the storm goes on. Worry too if a leak appears in the first rain after summer: it usually means a boot, a flashing or a valley failed during the dry months and has been open ever since.

Fix what actually failed, once, on a dry day. A patch made in the rain usually has to be done again, and the water that gets past it in the meantime costs more than the patch saved. Stop the water cheaply with a stopgap, then pay for one proper repair.

Something temporary: a heavy tarp lapped well past the damage and fixed so wind cannot get under it, or a temporary seal over a failed flashing, put on by someone who can reach it without standing on wet tile or a soft deck. Roofing cement smeared on a wet surface rarely holds. Whatever goes on in the rain is a stopgap, and the permanent repair is made once the roof is dry.

A small drip that stopped when the rain did, caught and marked, can usually wait for a dry-day repair. Water near a light fixture, a ceiling that bulges, or a leak that grows through the storm cannot wait at all. In Rialto the next rain may be weeks away, which makes it tempting to forget; the deck under a leak stays damp long after the ceiling looks dry.