I'm ripping out and re-tiling a 4'x5' shower in my home (tile pan leaking into basement closet ceiling). What masonry product/material is the best to use as a base under the new tile floor (over plywood and joists). I'm familiar with the shower pan liner procedure and drain connections, but what type of masonry products should I use to create the sloped floor toward the drain? Lowes tile mgr. recommended dry set mortar or professional mason mix with sand. I'm worried about cure time, structural strength and resistance to moisture exposure over time.

All the walls are going to be 1/2" Durock.

Also, the shower walls/ceiling will be cheap, white 4x4. Any hints on white color mortar/grout combinations to cut down the workload. Thank you for your advice.

check out http://www.ontariotile.com and look for the section on building shower pans. it will answer your questions on building the pan, with pictures to follow along the narrative.

the sand/portland mix in a 4:1 ratio is what you want, the bagged stuff is fine.

Thanks, I knew you'd have the right answer.

Built-up Shower pans are a problem! I have investivated several thousand and haven't found any correctly constructed to date. There will be a moisture migration problem if not done correctly. The sub-floor must be presloped to the drain weep holes a "Minimum of 1/4" per foot". This can be done with mortar or preformed products available from several manufacturers. The curb is extreemly important and the top surface of the framing must be presloped to the drain at least 1/4" per 3-1/2" to accent the curb membrane slope to the drain. The membrane needs to extend over the curb face and out unto the sub-floor so that no mortar is allowed to touch any material that can be damaged by moisture. The wall surfaces must also be covered with a membrane. Cement board walls are ok, however, all horizontal joints must be taped and a membrane must be in place behind the cement board. Any horizontal surface inside the shower must have a presloped membrane and a waterproof membrane installed. The floor must utilze a dry-packed mortar in order for water to flow through the floor to the weep holes and the weep holes must be protected to insure they are kept open.

quote:

The floor must utilze a dry-packed mortar in order for water to flow through the floor to the weep holes an

Dumb question...what is dry-packed mortar? and is pre-bagged mortar mix it?

Drypacked mortar is a mix where you only use enough water in the mix to allow the mix to stich together when you pick up a handfull and squeeze it tight and it sticks together in a ball, just ait was squeezed, and falls apart when dropped in the mixing box. That mix should be made with water that incorporates "Anti-hydro" additive added to the water in a ratio of 10/12 to 1, (water to additive) follow the addutive mfg. recommendations. This mix is then packed into the receptor/shower floor and screeded off to the proper slope. Allow this to set for a day and set up. then pouyr water on the pack to insure the water readily migrates into the float before setting the finished surface. The surface should NOT have a creamy steel troweled finish! This additive is used for waterproofing concrete and allows the receptor float to remain porous like a cement block. If the float is placed too wet, like a slab, then the water cannot migrate the water through to the weep holes and the water wtrapped at the walls will migrate up into the curb and wall assemblies. See the November 2005 "TILE LETTER" from NTCA.

TileGuyBob, I reviewed the procedures on http://www.ontariotile.com/preslope.html with the great step-by-step instructions. Am I understanding correctly that the under-liner mortar bed should be sloped toward the drain but the deck bed mortar does not require sloping? Or should both mortar bed be sloped at the 1/4" per foot to promote drainage from the top side as well as any weepage?

Chris,

Yes, put the slope on both layers. The top one is sloped so the water hitting the tile does not pond up on the floor but rather follows the pitch to the drain.
The second one under the liner is also sloped so any water that migrates through the grout and into the mud bed hits the sloped liner and that water runs to the weep holes under the drain flange. If that second one was not there the water would lay in the mud bed much like rain water in a kids sand box after a storm. The difference being it wont drain or evaporate in the shower and could cause a mold condition under your feet.