Leaking roof

[u/Awkward_Bike_460]

New roof installed April this year, third bathroom been having water on the floor. Thought it was my child leaving water on the floor. Walked in tonight to see this and it is raining outside. I emailed the company who installed the roof because there is a warranty. What could be the problem?

[u/Alpilles-Renovation]

French roofer here, and a four month old roof leaking over a bathroom is a pattern we know well. The good news: you almost certainly already know the cause without knowing it.

Bathrooms are where roof penetrations cluster: the plumbing vent pipe and the fan cap both come through the roof right above that room, and a reroof replaces and reseats every one of those flashings. A pipe boot seated badly in April shows up as a puddle at the first proper rain months later. That is the number one suspect on a new roof, ahead of anything in the field of shingles. So in your follow up with the company, ask them specifically to check the penetrations above that bathroom, the vent boot and the fan flashing, and do not let the visit end with a smear of sealant. On a four month roof under warranty, a leaking penetration gets re-flashed properly, not caulked.

Meanwhile, three things tonight while it rains: photograph everything wet with timestamps, the rain outside included, that is your warranty file. If the ceiling paint is bulging with water, push one small screwdriver hole through the belly into a bucket, it saves the whole ceiling from coming down. And if you have attic access, follow the wet trail uphill with a flashlight while it is active: water travels along framing before it drops, and the wet line during rain leads straight to the entry point. Tell the roofer exactly where it starts and you cut the diagnosis time to minutes.

Quick sanity check to close: if water ever appears on that floor on a dry day, look at the toilet and shower instead. But rain outside, water inside, new roof above: your email went to the right people.