How to Build a Shower Pan - Starting With The Basics

Learning how to build a shower pan starts with the basics. Funny how so many projects begin with getting the simplest things right. Installing a tile shower is no different. Here's how to start shower pan construction the right way.

If you install ceramic tile over a subfloor that moves, you get cracked tile surfaces. Usually the cracking starts in the grout lines. Now cracking in a shower floor is a disaster. It's basic that the subfloor is solid.

The tile standard says deflection of the subfloor with joists at 16 inch spacing can be only 0.04 inches for a four foot shower. That's not much movement. Any more than that and you're looking at major problems. What are keys to a solid subfloor?

First, make sure the floor joists are solid and at close enough spacing. The usual spacing is 16 inches on center for 2 x 10 joists. It may take extra support under the joists or it may take some cross bracing.

Well, if you're building over concrete subfloor, you're in the clear. Wood subfloors are usually plywood. A minimum of 3/4 inch plywood is what you should choose. But even that is marginal. Just the deflection of plywood of that thickness is marginal. Two sheets of 3/4 inch plywood are even better. That's one sheet over the other. That will only work, of course, if you have the vertical room for stacking two sheets.

Getting a tile shower off to the right start requires that the subfloor be solid with almost no movement under load. It's fairly simple to get the subfloor right. Just be sure you don't overlook this important basic step.

Bouncy subfloors equal cracked tile shower floors...