Okay I attempted to build my first shower pan recently after doing extensive reading & research. For those that are considering this for the 1st time-DON'T!

I am at a point where I got the sand mud (portland cement, fine sand & water mix) down on the shower floor, and have the outside edges about 1/2" higher than the drain, and sloping towards the drain all the way around. Sounds like I'm on the right track right? WRONG! I have a couple low spots that water will pool in before it reaches the drain. I was working in such a small spot-shower is only 30" X 48"-that I was using a 16" float. I could not get the top coat smooth enough to identify the low spots. Now that it is dry, I can put a straight edge down in different spots and clearly see the waves & ripples of varying high and low spots. I poured some water around the edges and it all runs towards the drain though.. EXCEPT one small area right at the edge of the drain that holds about 1/8" of water.

Now I know that this will not work. I understand that I will need to do something to fill/raise the low spots up so that all water that gets down to this sub-floor will run towards the drain weep holes. If the floor was right, I would simply put my 6 mil poly liner down, then another thin layer of sand mud, and then my tile. But I know not to put anything down until I get the low spots worked out..

Anybody have any suggestions? I was thinking I could cut backer board into 4 pizza shaped pieces (wide ends against the wall and narrow or skinny ends against the drain) and then put another thin layer of sand mud down just to bond the backer board to the floor. Then if that worked, I would simply seal up all the joints, and then put my plastic liner down on top of the backer board, and then sand mud, adhesive & tile on top of that.. Your thoughts?

I am desperate for a solution as I am stalled on my project until I get this worked out. Thanks in advance for your time and consideration!!!

 

Thinset will take up 1/8" deviation of the floor pan. Unless I am not getting the whole picture, you should be ok to install tile. The tile will need to be sloped well toward the drain. Post back if I am over simplifying the matter, but the ones I have installed, 1/8" isn't critical. If I had them any smoother, I wouldn't install tile.

 

I have to find a way to fill in the low spots.. Because water will pool in them if it ever gets past the tile/grout. If the water pools under the tile/grout, it will eventually break down the adhesive for all of the tiles and I will have to re-lay the entire floor. At least this is what I have been told.

This is the order everything has to go down:
Sand mud bed that will carry all water towards the drain, and drain weep holes
Plastic liner
Thin layer of sand mud
Adhesive
Tile

Since my mud bed has a low spot that is below the level of the weep holes, it has to be corrected before I move forward. At least this is what I have been told, and have read.

 

If I understand correctly, Larry is saying that it is no problem to build up the low spot with thinset.

 

Yes, the low spots will no longer be wet accumulation areas, since your thinset is basically creating a "skim" for your base. You will build up all areas approximately 1/4", level throughout with the proper trowel, so extra thinset will be deposited in the low areas, and a level tile surface will be created.