Proper Installation Method for a Shower Base and Repair Solutions for a Leaking Shower Base

The whole idea behind a 1 piece shower stall is no joints, no leaks, right? Wrong! Where there is water, it will leak!

Once again we see that improper installation techniques can cause a water leaking problem. There are a couple factors that enter into and contribute to leaking, let’s discuss them.

The less expensive shower bases are thinner and tend to flex when you move around on the shower floor and since the drain in these units is actually a friction fit system which allows for some movement water can seep through this area and cause a problem.

The friction fit is actually a good idea because there will always be a different rate of movement between the shower base, the structural floor, and the drain piping. The drain pipe for the shower is usually a 1 ½” or 2″ PVC pipe that slips through a rubber sleeve attached to the bottom of the shower base.

The problem in this case is that the floor of the shower unit actually flexes because of the lack of support from the bottom.

The proper method for installing the shower pan is to place it in a “bed” of mortar or similar acting product that will effectively cradle it and keep it from moving. My favorite product to do this is spray foam for a couple reasons. It creates the “bed” but it also deadens the sound and further acts as an insulator so as not to conduct cold through to the base itself.

You must dry fit the shower base first to make sure everything lines up. Once you set it in the foam you won’t get it back up.

To figure the thickness of the “bed” you need to lay the shower base upside down on carpet or some other soft surface as not to scratch it. Place a straight edge or level across the bottom and measure down to the floor of the unit. Add about ¾” to that measurement to get the thickness of the bed you need to put down.

When you have completed your dry fit you are ready to lay your “bed” down and lay your base into it. Simply spray the foam down on the floor and when it is built up to the desired height and coverage (generally 50% of the total area) lay the base into it. Press firmly, but do not step into it or push down aggressively or you will cause a gap to form between the base and the “bed” once the pressure is released. Leave it sit for the recommended drying time on the “bed” product you have used and you are good to go.

OK fine John, but mine is already installed; what can I do now to keep it from leaking?

Here is a solution that has worked in the past to solve the problem. Remove the drain gate, usually snaps in and out, although there may be a screw holding it in place. Clean the area around the joint between the fiberglass base and the rubber gasket. You may need to use a putty knife. Then wipe it clean with nail polish remover, or other degreaser type of cleaner. Be careful when using some products as they can discolor fiberglass or PVC.

Now using a flashlight, look into the drain, not too far down you will see the actual drain pipe itself. More than likely it will look like a white ring about 3/16″ thick. Continue looking carefully to the outside of this ring and you can see the rubber sleeve just to the outside of it. Clean the top edge of the pipe and the sleeve right above it.

Using some 100% silicone, I recommend GE brand, run a bead around the top edge of the pipe onto the sleeve and another bead on the top where the gasket meets the base. Moisten your finger with a little water and smooth out the bead, not too much, just make sure it is sealed all the way around and that you have left it about 1/8″ thick. Pure silicone will remain flexible when it dries, which will allow for the slight movement that can cause leaks. Let it dry for the recommended time and snap the drain in and you are good to go.

Something else you can do if you have access to the bottom of the floor under the shower, you can drill a few straw size holes under the base, be very careful you don’t drill through the base, and using a spray foam product, place some foam under the shower base. Do not walk on or use the shower until the foam has completely set, of your work will have been for nothing.

These repair methods will solve your problem and give you many years of a dry bathroom.