How to Detect and Fix a Bathroom Leak | This Old House

In this video, This Old House plumbing and heating contractor Richard Trethewey shows how to find and fix a bathroom leak. (See below for a shopping list and tools.)

Richard helped a homeowner with a mysterious leak that caused a water stain on the foyer ceiling. First, Richard went to the upstairs bathroom and inspected the bathtub and toilet. He also looked at the floor tile and shower door. He then decided to open up the ceiling below to help determine the source of the leak. Using a reciprocating saw, Richard cut out a large, square piece of drywall just below the bathtub and toilet. With the ceiling opened up, Richard determined that neither the toilet nor bathtub drains were leaking. Back upstairs, Richard discovered that water was leaking around the shower door and down through the floor. To fix the problem, Richard installed a "door sweep" on the shower door to prevent water from escaping. He then removed some old tile grout around the base of the tub and applied a bead of silicone caulking, making a watertight seal. Finally, Richard replaced the ceiling drywall below and the repair was complete.

Shopping List for How to Detect and Fix a Bathroom Leak:
- door sweep, for creating watertight seal along vertical edge of shower door
- silicone caulk, for sealing joint between floor and tub
- drywall, used to patch ceiling below bathroom
- drywall screws, for attaching new drywall patch to ceiling joists
- joint compound and drywall tape, for finishing new drywall patch
- primer and paint topcoat, for covering drywall patch

Tools for How to Detect and Fix a Bathroom Leak:
- chalk line, used to snap cutting lines on existing ceiling
- reciprocating saw, for cutting out water-damaged ceiling
- utility knife or grout saw, used to remove old grout from joint between floor tile and tub
- caulking gun, for applying silicone caulk
- cordless drill, used to drive in drywall screws
- drywall taping knives, used to finish drywall ceiling patch
- paintbrush and paint roller, for priming and painting drywall patch

About Ask This Old House TV:
Homeowners have a virtual truckload of questions for us on smaller projects, and we're ready to answer. Ask This Old House solves the steady stream of home improvement problems faced by our viewers—and we make house calls! Ask This Old House features some familiar faces from This Old House, including Kevin O'Connor, general contractor Tom Silva, plumbing and heating expert Richard Trethewey, and landscape contractor Roger Cook.

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How to Detect and Fix a Bathroom Leak | This Old House

[toobigal]

I hope he checked to see whether sealing the door and caulking the floor fixed the leak before he put back the ceiling.

[heidis]

Wait... He said he was removing the ceiling to "fix it once, and fix it right." I thought that would have included some sort of removal / treatment for the wood / insulation that was rotten / moldy. I mean, at least spray some bleach and let it air dry for a couple days. If "fixing it" just meant to "stop the leak", then just seal up all the possible spots, which should be done anyway. I still don't understand why he removed the ceiling, only to measure from the wall to the wet spot that was visible with the ceiling intact?!

[theresafountain]

Cool! Thank you! I am doing so many projects around the house to get it ready to sell. I would like it move in ready and have not cut any corners! Thank you again for the video!

[johntilson]

I thought I was the only plumber that fixed drywall! Most of 'em leave it for someone else to fix!

[Rexcrispy]

I have a similar situation, I was under the impression you want to try and remove and repair any moldy, rotted wood? Is that not necessary?

[viboonhansahiranvadee]

Thank you for your video. Luckily, I don't have to cut my ceiling, just took out a can light and I can see where's the leaks came from, then measured as suggested from the video and found the source of the leaks.

[ryantfinchum]

That door is familiar... Looks like the Delta frameless door I just installed and leaks in the exact same way... Unbelievable

[brutebiz]

Not sure I would use a reciprocating saw without turning off the breaker fuses feeding power to the second floor. FYI: The ceiling drywall needed to be removed and potential mold spores assessed and treated.

[hotdog]

Great video. I'd just like to add that the ideal situation is to use a battery operated recipricating saw or manual drywall saw, but first switch the main power switch for the house off. It might just save a life in case there are electrical cables behind the drywall and no electrical safety switches on every circuit. I can see you went shallow when cutting through the drywall but others might not.

[reno]

I have similar situation, so it best to open ceiling up if definitely have water damage in a section

[mikegert]

If water was penetrating the sub-floor to present on the joists & below on the ceiling then it would most certainly have been making its way beneath the underlayment and sheet vinyl finish floor.
I bet the finish flooring was obviously swollen to touch.
It was also possible that the wet rot damage had gone into the next joist bay.

The guy made a good call but then made a very shallow response to what he had exposed.

[jordanDeadheadTS]

Lolol 😂 The best part is when shes caulking and he’s like “you’re doing great!“

[krakenthrottle]

He used a recip saw where he should have used a key hole saw (if you don't have a keyhole saw, a hack saw blade and a pair of vise grips or a knife will do some knives will obviously be better than others). The reason for using a key hole saw is you are less likely to cut into/through wires. This is both for safety and to minimise the chances of doing more damage than what was done by the leak.

[aprilchiu]

The wooden structure of the house is wet and molded as well. Is it necessary to repair that part as well instead of just stopping the water from leaking down the wall, and replacing the old ceiling with a new one?

[georgeplagianos]

thanks for all the investigative work is finding where the leak is from. I had the same problem. it was going to thru the floor into my tenant's apartments bathroom. and it was from the hot and cold fucets dripping backwards down to the piping behind the wall going downstairs so I had to take hot and cold water apart and replace the stems and rethreaded with that Teflon tape. spent six months so far it's working no leak.. the only way I found that there was no more leaks was I didn't rush to put that bored in the apartment below me up so soon. I also gave time. the only way I found out there were no more leaks was I did not rush to put that plaster board up so soon. it also gave time for the water damage to dry up underneath the bathtub. yeah I took a few months 10 it didn't complain that's fine. thanks again for these tips you poted here. take care

[Allbbrz]

Heh... I love that they always make the actual homeowner take part and do the job

[farukatasever]

I had similar problem. My solution was install shower rod and curtain inside glass enclosure after fixing the problem.

[tenthdimension]

Never use a power saw to do that. Too easy to cut a wire or pipe. Use a keyhole saw.

[Chuckish]

I wonder if Tommy was standing off camera to make sure Richard did it right.

[quickeasyideacookingfoodti]

Great job! please tell me how much do you charge for only this work ?