View Full Version : Pre-Slope Question

12-08-2009, 12:16 PM
Hello all.

I have a question on pre-slope for shower pan. I used 4:1 ratio

Im building a shower pan for tile shower and just checked the pre-slope one time before placing plastic liner. I noticed a couple things.

-In a couple areas along edge the pre-slope sounds hollow. All other areas sound solid. All surface is hard.

-I noticed an area that isnt sloped correctly. Almost level, dip. Needs more material for proper slope to drain.


1. Is hollow sound ok?

2. Can I mix more mud and add on top of my pre slope in the areas that need additional material for correct slope? If not, what material to use for this.

Thank you in advance. Any suggestions much appreciated!


12-08-2009, 03:39 PM
Is the pan built on concrete slab or a plywooden subfloor? How thick is it in the area that sounds hollow? If plywood, did you staple down some lath?

You can fill the dips in with thinset. The type you choose will depend on how thick it needs to be. Normal thinset can be used up to about 1/4" thick. If it needs to be thicker, then, I'd use a medium bed mortar (often called granite and marble mortar) - it can support thicknesses up to at least 1/2" in one layer.

For the best help on building a shower and tiling, check out www.johnbridge.com (http://www.johnbridge.com).

12-09-2009, 05:49 AM
Thank you for the info.

The pre slope is on top of concrete slab. The thickness in areas of hollow sound are about 3/4" to 1". Areas are along outside edges.

Thanks again!

12-09-2009, 07:20 AM
You may not have a good bond to the slab. This isn't catastrophic. One technique is to make a slurry of cement, spread a thin layer on the slab, then throw your deck mud down. This will make it bond to the slab. If you don't, it probably won't. The best source of tiling info is at www.johnbridge.com. (http://www.johnbridge.com.)