How to Fix a Shower Leak Behind the Wall

This project explains how to fix a shower leak behind the wall by cutting an access panel in the drywall to find and fix the plumbing leak.

I noticed a water dripping from the ceiling of the walk-in closet on the main floor. Based on the floor and room layout, I realized the upstairs shower and bathtub is located directly overhead.


Leaky Shower Repair: Water Stain on the Drywall Ceiling

Leaky Shower Repair: Water Stain on the Drywall Ceiling

How to Fix a Shower Leak Behind the Wall

My suspicion is the leak was coming from either the shower water supply or drain plumbing. The problem is that I had no access to the shower plumbing because it was concealed behind the drywall – many times there will be a plumbing access panel, but there was none here. I would have to cut a hole in the drywall in order to inspect the shower plumbing and find the leak.

Showers and bathtubs can be creative in the way they leak. It’s a matter of remembering that water runs downhill and tracing the leak to the source.

Aside: Also see How to Fix a Leaky Shower Drain for a related repair.

Cut an Inspection Opening in the Drywall

I began by locating the center of the wet wall (i.e. wall with the plumbing). I gently probed (don’t want to puncture a water pipe!) for wall studs by driving a small finishing nail through the drywall to see if it contacted a stud, moving the nail about one inch left and right until I had cleared a 6 inch length. There shouldn’t be framing studs in the center area of the wet wall to allow room for the shower valve and I found my assumption was correct.

Shower Leak Repair: Locate the 2x4 Studs in the Wet Wall (Drywall)

Shower Leak Repair: Locate the 2×4 Studs in the Wet Wall (Drywall)

Here’s a closeup of the nail and test holes.

Shower Leak Behind the Wall: Check for Wall Studs

Shower Leak Behind the Wall: Check for Wall Studs

Now that I had confirmed there are no wall studs in the center section of the wet wall, I used a Rotozip spiral saw to cut a small inspection hole in the drywall to access the shower plumbing.

I cut a small inspection hole in the drywall because:

  1. I would have to repair the drywall later and small holes are easier to fix than large ones.
  2. Wallpaper is hard to repair as seams will show.
  3. I needed to locate the plumbing and wall studs before going any further.
Shower Leak Behind the Wall: Saw an Inspection Hole in the Drywall

Shower Leak Behind the Wall: Saw an Inspection Hole in the Drywall

The small inspection hole (above) allowed me to reach inside and locate the wall studs and plumbing; I also confirmed there was no electrical wiring in the wall. The inspection opening was enlarged to the span the width between the wall studs to dimensions of ~10.5 inches wide and ~8.5 inches tall.

Shower Leak Behind the Wall: Drywall Inspection Hole

Shower Leak Behind the Wall: Drywall Inspection Hole

Below is a closeup of the hot & cold copper water supply pipes and the PVC overflow drain for the bathtub. An immediate concern are the greenish/white streaks on the copper pipes from dripping water. The pipes were dry and at this point I wasn’t sure if this were a historical artifact or recently made.

A strip of blue masking tape was applied to the bottom edge of the opening to reduce the amount of drywall dust rubbed off on my arms.

Shower Leak in the Wall: Drywall Access Hole and Plumbing

Shower Leak in the Wall: Drywall Access Hole and Plumbing

Water stains can be seen on the drywall ceiling below the bathtub:

Shower Leak Repair: Water Stains on the Drywall Ceiling below the Bathtub

Shower Leak Repair: Water Stains on the Drywall Ceiling below the Bathtub

Shower and Bathtub Drain Leak Checking

A flashlight and mirror are used to inspect the bathtub drain for leaks. The bathtub was filled with several inches of water and allowed to stand for 15 minutes. No leaks were found at the bathtub drain.

Inspecting the Bathtub Drain for Leaks

Inspecting the Bathtub Drain for Leaks

Check the Shower Plumbing for Leaks

I turned on the shower and used the mirror and flashlight to inspect the copper piping, shower valve and shower head arm inside the wall. Bingo! Lot’s of dripping water.

Repair a Shower Leak Behind the Wall: Plumbing Inspection

Repair a Shower Leak Behind the Wall: Plumbing Inspection

Looking up inside the wall at the shower leak. Drops of water are falling from the shower valve:

Water Dripping from the Shower Valve

Water Dripping from the Shower Valve

“Uh Oh!” If the shower valve is bad then I’ll have to cut another drywall access panel opening to fix the valve. That would be an ugly drywall repair. Notice the water stains on the drywall and chalky deposits on the copper pipes. The drywall integrity was fine – dry and solid – in spite of the water stains. I gave it a good shot of Lysol to discourage mold growth.

Upon closer inspection with the flashlight and mirror I was able catch a glimpse of the water dripping from the shower arm (up high by the shower head) onto the shower valve. Good! At the least the shower valve is not leaking.

Water is dripping on the subfloor from the shower arm and elbow next photo. The white stuff on the 2×4 base plate is drywall dust when I cut the access hole:

Repair a Shower Leak behind the Wall: Water Dripping onto the Subfloor

Repair a Shower Leak behind the Wall: Water Dripping onto the Subfloor

The shower leak is inside the wall at the connection between shower arm and elbow behind the tile:

Shower Leak behind the Wall: Shower Head

Shower Leak behind the Wall: Shower Head

The shower head and escutcheon (trim plate) are removed to get a look at the shower plumbing inside the wall:

Shower Leak inside the Wall: Shower Arm and Wall Tile

Shower Leak inside the Wall: Shower Arm and Wall Tile

This project is continued in How to Fix a Shower Leak Behind the Wall – Part 2.

Take care,

Bob Jackson

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4 Responses to How to Fix a Shower Leak Behind the Wall

  1. Penny October 25, 2009 at 9:57 pm #

    Hello,
    Thank you for such a riveting article!
    I just bought a house, that has a leak behind the shower wall, and I wanted to see if anyone else had fixed a similar problem. Happily I found your terrific article. And I realize it’s a lot bigger task than I could ever hope to accomplish on my own. I especially like how you made the detection hole large enough to locate the source of the leak but small enough to cover with a pretty Grill, in case you needed to go into the wall again. That was clever! And great to follow along with your photos…
    Thanks again for the great insight.
    Penny in Las Vegas.

  2. grindit April 16, 2010 at 5:21 pm #

    Thank you, our problem was exactly the same.The shower/tub above a walk-in closet/pantry,where the twotop shelves were for towels and wash cloths.They were wet andI had to shut the bathroom shower down.I ended updoing everything that you did {taught me}.It ended up being the valve,
    26 years old! Thank you again,Iused the same vent cover because your
    pictures made it look better than the access panels on the market.
    You dont have to cover it up with a piece of furniture. THANKS!!!
    grindit

  3. frankie December 11, 2014 at 4:12 pm #

    where my shower arm connects to the plastic piece behind the wallpaper? I was wondering what’s the best way to make the area I cut out look good cuz I’m going to replace that little section of wallpaper I cut out to fix my cracked plastic piece with drywall?

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