If building a shower pan with mortar is your next project then this page will be really valuable to you. It’s a multi-step process that is simple to do, but as with all shower pans, you’ll need to make sure there aren’t any leaks.
The advantage of building your own shower pan is that it can fit anywhere because you just frame it in. If you was to buy a ready-made shower pan and shower stall surround, you would have to build an exact frame to match the pre-built shower pan.
The floor will need to be covered with either tar paper or plastic to prevent it from sucking moisture out of the mortar. Tar paper is probably better than anything else.
Wire mesh or lath can be bought at Home depot or Lowes by the cement supplies. Secure the mesh to the floor. This will help make the mortar bed stronger.
The best shower pan mortar is just Portland cement mix, but you can use thinset mortar also. The mix needs to be strong especially where you step into the shower on the curb. The latex additive will help a lot.
It helps to add a latex additive to the mortar mix. This almost doubles the strength of the mortar. You can find this stuff at any building supplies store. The curb that keeps the water form running onto your bathroom floor can break under pressure if the mortar isn’t strong enough.
The latex additive is about half a gallon to 4 bags of mortar. Add water and mix it really well. The mortar needs to be mixed fairly dry. It shouldn’t be runny or sloshing around or it will take several days to dry.
Before you dump the mortar down onto the floor, make sure the drain is plugged with a rag or something.
Now we spread the mortar starting from the shower walls and working our way inward to the drain. We need to get a fair amount of slope so that water flows into the drain without making puddles.
This is the first layer of mortar when building-a-shower-pan inside the stall framework. It will be level with the top of the black drain base which is in the photo with the white clamp ring inserted. The mortar bed will be about 2- inches thick.
Let this dry for at least 24 hours. Next we will apply the rubber membrane.