Hello all,

Looking for a little advice, I am going to be installing a solid piece single threshold shower pan. It is produced by a company here in Ohio called Rainbow.

The specifics of the project are - the Bathroom is currently gutted to the studded walls and a 3/4" OSB sub-floor. I plan on tiling the walls of the shower and the floor of the bathroom. I will be placing Backer Board on the walls in the shower and the floor.

The manufacture says that the base is simply placed in position and shimmed as needed (no thinset, ect).

Can anyone offer some advice on weather I should continue the Backer Board that I am placing on the floor to be under the base, or should I place the base on the OSB then run the Backer Board to the threshold. I was thinking that if I ran the Backer Board on the entire floor and into the Shower stall it only adds about 1 additional sheet and would offer a level of protection if water gets between the Base and the tile at the edge of the threshold.

Also, as an off beat question - if you had the option, would you run tile completely under your vanity or would you place the vanity on the sub-floor then tile to the edge? (vanity is 6' x 22" so it ass like 12 Sq ft of tile at or about 60 bucks)

Thanks in advance for all the help