Key takeaways
- In a house built around the 1960s, the shower tile usually outlasts the wall behind it.
- Behind it you will find a mortar bed or greenboard with no waterproof membrane, often a damp subfloor under the tub, and galvanized pipe near the end of its 40 to 60 year life.
- A shower under about 20 years old with a dry floor is worth maintaining; an older one usually needs the wall replaced.
Tap the almond tile on the tub wall, a foot above the rim, and you get a solid click. Tap the bottom row, where the grout keeps going gray, and in a lot of the ranches our crews open in Anderson Township and Fort Thomas, Kentucky, the sound goes dull. The tile is fine. This is what is behind shower tile in a house built around 1965, in the order our installers meet it on demo day.
The tile is the last thing in that wall to fail
The 4-inch square tile your house came with was made to outlast the house. It is glazed ceramic, and we pull it off whole after 60 years with the glaze unmarked. If you have told a contractor "the tile is still perfect," you were right.
The tile is also the hard shell over everything that is not perfect. Water gets past it through the grout joints and the caulk line at the tub, and once it is through, the same tile that kept it out of the room keeps it in the wall.
Mortar bed or greenboard: the two walls behind 1960s shower tile
Tile setters did these bathrooms one of two ways. The median house in Hamilton County was built in 1963, by the state's count, so a lot of local bathrooms sit right on the line between the two.
In a mortar-bed job, the tile setter nailed metal lath to the studs, floated a bed of portland cement mortar over it, and set the tile into that bed. The bed runs 1 1/4 to 2 inches thick, per Archtoolbox. These walls fail at the bottom course, where the mortar has stayed wet for decades and the lath behind it has rusted.
In a thin-set job, the setter hung gypsum board on the studs, in many houses the green water-resistant kind, and glued the tile to it with a 3/16-inch layer of mortar or mastic. Greenboard stayed legal for tub and shower walls until the 2006 International Residential Code took it out of wet areas, as Walls & Ceilings reported in 2004. The paper face on that board is the part that goes soft. A dull tap on a thin-set wall means the board has absorbed water and let go of the tile.
If your house was built in the 1970s or later, assume thin-set over greenboard. Before about 1960, assume a mortar bed. For the years in between, the tap test is the fastest tell.
No waterproof membrane behind the tile
Behind either wall type you find the studs, and in most of these bathrooms you find nothing between the wall and the studs. Some mortar-bed setters put tar paper behind the lath. Behind greenboard, in the houses we open, there is no membrane at all.
Grout is porous. The gray that comes back a year after you clean it is water and soap moving through it, which we covered in the grout post. Some of that water reaches the back of the wall and sits against the studs and the bottom plate, the horizontal board the studs stand on.
The Environmental Protection Agency's guidance for water-damaged buildings says to dry wet materials within 24 to 48 hours, and it treats wallboard that has swelled or lost its seams as material to remove and replace. A shower wall gets wet twice a day and has about 20 hours to dry in between. The back of it has not had 48 dry hours since the Johnson administration.
The subfloor under a 1960s cast-iron tub
The cast-iron tub in a 1960s ranch sits on the subfloor, the plywood or boards the finish floor is nailed to. The tub apron hides the joint between the tub and the floor, and that joint is where the caulk you have replaced three times lives.
Water that passes the caulk runs down the outside of the tub and onto the subfloor. In some ranches you can see the result from the basement as a stain on the joists. From above, you feel it as the soft spot in the floor next to the tub. The floor is not going to fall in tomorrow. It is telling you the subfloor has been wet long enough to lose its stiffness, which takes plywood years and particleboard a season.
The galvanized pipe in the wall is as old as the tile
In many 1960s houses the hot and cold lines feeding the tub valve are galvanized steel, which InspectApedia puts at a 40 to 60 year service life. Your house is 60. Galvanized pipe closes up from the inside with rust scale, which is why the hot water in the master shower comes out slower than it did, and why the spout coughs rusty water for a second after a vacation.
You cannot see any of this from inside the bathroom. It sits in the same stud bay the water has been running into.
Four things to check this weekend, no tools
Most of this you can learn from the finished side.
- Tap every tile on the tub wall with a knuckle, from the ceiling down. Mark where the sound changes with a piece of painter's tape.
- Press the floor with your heel along the tub apron and in front of the toilet. Any give is a wet subfloor.
- Go to the basement or crawlspace and look at the ceiling under the bathroom. Stains or rusty drips on the joists tell you how long this has been going on.
- Open the access panel behind the tub wall, if the house has one, in the closet or hallway on the other side. Gray metal with rust at the threaded joints is galvanized, and copper is orange or brown. White plastic means someone already made a repair.
If all four come back clean, the grout routine in the earlier post buys you years. If two of them do not, the problem is past what regrouting can reach.
When to maintain a tiled shower and when to replace it
A shower under about 20 years old, built after the greenboard rule changed, with a dry floor and a solid tap, is worth maintaining. The showers our crews replace are 20 years old and up, and in those the wall behind the tile is the job. Regrouting puts new grout over the same wet board, and the gray comes back on schedule.
At that age the choice is between a new tiled shower from a tile contractor, who will tear out to the studs and build back with a cement backer and a waterproofing layer, and a shower with no grout. Either way the wall comes out and the crew sees the subfloor and the pipe.
A grout-free shower is one solid-surface panel per wall, measured to your bathroom and made to those numbers before anyone shows up. Our installers take the tub or shower area to the studs in the morning, handle what they find back there, and have the new base, walls and fixtures in by evening. You take your first shower the next morning. The floor, vanity and toilet are a separate, longer job, and we say so before you sign. With promotional financing, qualified buyers get the new shower for as low as $150 a month, or 12 months no interest, on approved credit. The one-day remodel page walks through install day.
If you are not there yet, do the four checks and write down what you found. The grout post has the weekend routine that keeps a sound wall going, and the post on the soft spot in the floor next to the tub covers the same water from below.
For the full picture of how an older shower fails, and when to stop fixing it, start with your 20-year-old shower: what fails first.
