This is likely one of the most frustrating types of leak in your plumbing system. In many modern houses, there is a plumbing access panel but if there is none, tearing down part of the wall is your best option. Below is the procedure for fixing a shower leak behind a wall.
Locating the damp part of the wall will guide your repair, and find the center of the wet spot. Use a nail or screwdriver and probe around looking for the wall studs. Ensure your probing is gentle to avoid puncturing any water pipes. At the center of the wet spot, framing stubs should be none existent in the wall.
Cut a small inspection hole around the wet spot on the wall and feel with your finger the location of the leak. Wrap the edges of the opening with masking tape to reduce the amount of drywall dust rubbing off on your arms.
Turn on the shower and using a torch and a mirror, locate the area of the pipe that is leaking. One of the common sources of leaks is loose pipe connections and using a pipe wrench tightens the loose shower faucet or connection.
The plumbing panel should allow the tightening without causing damage to the shower’s surrounding. If the leak is coming from punctured pipes or the soldering between the shower pipes, then you will have to call up a professional plumber.
Leaking Shower Arm and Elbow Connection
Remove the escutcheon and look for a leak at the connection between the shower arm and the elbow. Proceed to unscrew the shower arm and inspect the threading and pipe joint compound. The leak could be because of the pipe joint compound becoming dry and brittle.
Remove the dry pipe joint from the shower arm threads with a brass-bristle brush and polish the arm with a cloth preferably made of cotton.
Seal the threads of the shower arm with plumber’s Teflon tape wrapping it in the anti-clockwise direction. You will be able to use a pipe wrench to tighten the connection without the tape unraveling.
Clean the old and dry pipe joint compound from the shower elbow and reattach the shower arm. Replace the escutcheon, turn on the water, and if there are no leaks, cover the panel cutaway with a return grill. Use it for regular maintenance of the plumbing behind the wall.
Leaving a leak in the wall could cause severe damage to your walls, floor, and paint. In the case, you do not have the expertise and the time to deal with the leaking shower behind the wall, call a plumber in your locality.