I am having a slab poured for an addition - the bathroom will have a
sunken (4 inch) shower stall area - Does a membrane need to be put
down before tiling the floor of the shower or can the tile be set
directly on the concrete?

I would appreciate any advice.

you tile on concrete , not a rubber membrane. You would use the membrane
before you pour the concrete, under the concrete.

On 5 Nov 2003 05:34:29 -0800, wrote:

I am having a slab poured for an addition - the bathroom will have a
sunken (4 inch) shower stall area - Does a membrane need to be put
down before tiling the floor of the shower or can the tile be set
directly on the concrete?

Normally, sloped concrete, then membrane, then a mortar bed, then
tile.

Jeff