Shower Leaking on to Downstairs Ceiling

Colebean asks,

We have a 1975 home. We noticed a water stain on our ceiling in our kitchen. It is about the size of a silver dollar. The master bedroom shower is directly above. We stopped using the shower in that bathroom until we solve this problem. We understand that the ceramic tile floors and walls back in the 70’s were set into mortar. We have been told that we may have to replace the membrane which is either under or over our mortar base on the floor because it has probably rotted out by now. Are there any products out there that will solve this problem without a tear out of the upstairs bath shower floor? We could regrout and then recaulk the perimeter of the shower floor (we do see an itty bitty crack in the grout between the floor and wall and we suspect this is where the water is coming from. We have heard of a product called spectra that is waterproof epoxy grout. Would this work? Or could/should we just have the floor tiles lifted and maybe one row around the perimeter too, put a new membrane down and then retile with maybe a stone/pebble type floor and just keep the original wall tiles. We want to solve the problem but don’t want to tear apart the bathroom. We have been told that if we remove the tiles from the mortar we are sure to have cracks occur around the house from the pounding out of the tile. We just did a downstairs remodel/addition and don’t want to ruin that and have new cracks in our walls and ceilings. Another person said that you could just retile over the existing tile and that the mortar base is the best base you can have. However, retiling over the tile would make the shower smaller and if continued to match the whole room, floor and other tile walls, it would cause the floor to be higher too. Help! We just want to fix the leak, not do a major remodel. Are there any products that could help?

Our Answer

It is doubtful that the leak is occurring due to a leak in the tile. The most common leak in these older showers is the drain to tile connection or the faucets or the shower head. The difficult part about this is that if the leak is from the shower base, the shower base will require removal to repair.

It is common for the shower base to be a mud floor system with drain. Typically they used a lead pan which was a sheet of lead about 1/8 inch thick that was laid down on a pitched bed of cement and sand. the edges of the pan were brought up the wall a few inches above the door sill height. A metal drain was inserted through the pan that had tiny drain holes set just above the level of the lead itself. Then a 2nd layer of sand and Portland cement was mixed with just enough water to make it stiff enough to be formed into a ball without falling apart. This was then laid over the lead pan and pitched towards the drain top itself. Soon after the tile was placed onto that. The reason for the tiny holes set in the drain just above the lead pan was to collect any moisture that seeps through the grout floor. It moves down to the lead pan and then because its pitched runs towards the tiny drain holes and into the drain itself. After many years this area of the pan corrodes and the pan begins to leak right at that point where the drain goes through it. If this is indeed your issue, the base of the shower will require removal.

Check the shower head and faucets first. It is not uncommon for shower heads to spray back into the wall causing water to run down the back of the shower wall. Then check the faucets when the shower is running. If water is leaking out from behind the handles water then can easily run behind the wall through the chrome tubes that cover the handles for decoration.Both of these are easy fixes.

Then run the shower as normal. Place a dry towel just outside the door. Once done with the shower, check the towel for any water. Door frames often leak as well. The water can run outside of the shower door area onto the floor of the bathroom and leak between the shower and the floor area. This is a very common issue with tubs. But it also happens a lot with showers as well.

To determine if its something else such as a leak in the drain or wall you can do a few things. Measure exactly were the stain is coming from to see if it is under the drain above. You can place a flat rubber drain stopper used on tubs so water does not go down the drain. Fill the shower up to just before the saddle of the door entry. Wait several min to see if the water goes down. If so the leak is the wall to pan area. If not you now have reduced the leak to the drain line itself.

If you suspect that the drain is at fault and before you tear out the shower to fix. It is much easier to cut a small access hole about 12 inches square and do a look see when the shower is running. Patching a ceiling hole and painting it is much easier then finding out after you tore out the shower pan only to find the door frame was leaking.