It’s a common misconception that the tile and grout on the floor of a bathroom shower are a waterproofing barrier, and that cracked or loose grout can cause leakage. Actually, tile is installed as a decorative and wear-resistant surface for the real waterproof barrier underneath: a liner that today is usually a prefabricated fiberglass pan, or custom shapes are formed in place of flexible rubber-like sheet material. Older shower pans were metal, and their lifespan is typically 40 to 50 years. The building codes refer to them as “shower liners."

   Whatever the material, like any other components of a home, shower liners deteriorate with age and, at some point, begin to leak. Also, a leak can be caused by an installation defect in a new shower liner. Home inspectors test a shower pan by placing a rubber stopper over the drain, filling the shower floor with a couple of inches of water and letting it sit for about 15 minutes.

    If there is heavy leakage, puddling water or stains on the wall around the the shower—including at the other side of common walls between the shower and adjacent rooms—will be obvious. Smaller leaks can be caught with a moisture meter or infrared camera. We like to use hot water to fill the shower floor, because leaks show up as bright yellow hot spots on our infrared camera, as in the photo sequences below of the shower curb and the common wall of adjacent closet.

   Sometimes visible evidence of a shower leak is on the exterior wall. The wet stain and green algae growth on the side of the floor slab in the photo below aligned with the side of a master bathroom shower, and the area gushed water when the pan was tested.

The labor and materials cost for a new liner, mortar bed, and tile replacement make a failed shower pan an expensive defect to repair. Plus, the potential for damaged wood wall framing and mold growth in the wall cavity if it has been a long-term problem may increase the cost further. 

   So be sure to ask your home inspector to do a shower pan test during the home inspection, especially if it is an older home. However, it is worth noting that a shower pan test is not required by the Standards of Practice for home inspectors under Florida Statute 61-30.806, which states that “the inspector is not required to test shower pans, tub and shower surrounds for leakage.” So not every inspector will do it for you. 

    A new or replacement shower pan/liner, however, is required to be tested as part of the plumbing permit inspection process by the local building department. The standard, per P2503.6 of the Residential Edition of the Florida Building Code (FBC) is a plugged drain with 2 inches of standing water for 15 minutes and no leaks. The International Residential Code (IRC) is similar.

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Here’s links to a collection of our other blog posts about PLUMBING:

• How can I protect my pipes to keep them from bursting during a hard winter freeze in North Florida?

• Why is there sand in the bottom of my toilet tank?  

• What causes a gurgling sound when a bathtub or sink drains? 

• Are drop-in toilet bowl cleaner tablets safe? 

• What can I add to my septic tank to help it work better?

• What are the code requirements for layout of drain piping under sinks? 

• Why is there mold inside my toilet tank?  

• What are the pros and cons of a wall-mounted toilet?

• Which plumbing fixtures require water shut off valves in a home? 

• How can I tell if a house is connected to a septic tank system or sewer?

• Are plastic pipes (PVC, CPVC, and PEX) safe for drinking water? 

• Why is a backflow preventer required on lawn sprinkler systems? 

• How can I locate my septic tank? 

• Is a hot water faucet handle required to be on the left? 

• Can you live in a house while the plumbing is being replaced? 

• Why is the European-style bottle trap not approved by the plumbing codes in the U.S.? 

• Why can't PVC be used for water pipe inside a house? 

• What are the common problems to look for when the plumbing has been replaced in a house? 

• What's that powdery crust on the pipe connections at the water heater? 

• How can I tell what type of plumbing pipe I have? 

• What causes low water pressure in a house?

• Should I call a plumber or septic tank contractor when my septic tank backs up into the house? 

• How do I get rid of the sewer gas smell in my house?  

• What are the pipes on my roof? 

• Should I wrap the water heater with an insulation blanket? 

• My water bill went way up last month. How do I look for a leak?

• Why does the water have a rotten-egg smell in some empty houses? 

• What is an "S-Trap" under my sink? Why is it a problem? 

• Where is the septic tank? Are you going to inspect it? 

• What does polybutylene pipe look like? Why is it a problem?

• Which water pipes are an insurance problem and possibly uninsurable? 

• Does a home inspector check the plumbing under the floor slab?

• Is it alright to disconnect the washing machine drain from the septic tank and divert it to the ground in the yard?

      Visit our PLUMBING page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.