Repairing/Improving Insufficient Mortar Slope - TilersForums.com

[bmurphywa]

Well I installed my first shower (in my own home) and carefully created a pre-slope, used a three-piece drain, weep hole guard and created a properly sloped mortar bed (almost). I have not yet laid the floor tiles. My question relates to the "almost" qualifier. Generally, the mortar bed is sloped properly but there are a few low spots away from the drain. I would like to improve this situation before laying the tile and I am wondering what the best way to do this is. Can I just mix up some more mortar and lay that on top of the current cured mortar bed? Would thinset work better? Something else? Thanks in advance!

Bill Murphy

 

[Rob Z]

Hi Bill,

if those low spots are too low, then I would skim them with thinset. The deck mud that you used to make the shower floor won't bond to the existing mud nor will it work in a thin cross-section.

 

[bmurphywa]

Thanks RobZ. I had my doubts about trying to use mortar on top of the base layer. Thinset it is.

Bill

 

[Leatherface]

thinset is ok,
rule of thumb, your slope only has to be 1 in 40 slope towards drain

 

[bmurphywa]

Thanks for the confirmation on the thinset. I generally do have a 1 in 40 slope but there are some low spots. I wanted to "fill" these before tiling to avoid any puddling. Thanks again.

 

[Rob Z]

Bill, If you've never done this before, I suggest mixing your thinset wetter than normal for skimming the mortar. The mud will be thirsty and the thinset won't trowel as easily and smoothly as it locks while you're working it.

Are you in the US or Canada?

 

[bmurphywa]

Good idea. Thanks. Bainbridge Island, WA (near Seattle).

 

[R Montgomery]

Yea thin set.If it's a larger area than your flat trowel can deal with use a straight edge or a length of redwood lath.You said "pre-slope"so this is the float that will be under the shower pan liner?
(Thanks for the 1 in 40 fall Leatherface.It's 1 in 48 in the states ie 1/4 inch per foot.)
You're at home so you might not be having a shower pan inspection but if you are make sure the fall is steep enough as the inspectors may stick a tape measure in the water.If you are not having it inspected I would still make sure that you do a water test.

 

[bmurphywa]

Actually, it's the main slope I'm talking about. I completed the pre-slope and that was fine and installed a shower pan liner over that into which I am installing the mortar bed with the "main" slope. By the way, the other reason I am doing this is that I created the 1/4" slope and then read that 1/2" is better as I am installing a pebble floor rather than flat tiles and the extra slope is recommended to ensure the water drains well around the pebbles.

 

[R Montgomery]

Never heard that before but it's interesting.I've only ever installed a couple of pebble floors.I must have thrown away the cut sheet,not read it or missed it.With a tile that could be slippery when wet I would think it was a terrible idea but with a small tile and a lot of grout to prevent you from slipping it kind of makes sense as long as your drain is roughly in the center.