Hey folks,

I have been reading hundreds of posts and articles on the subject of tiling, backerboards, installation, tips, techniques, etc. but have not gotten enough detail to answer my question sufficiently enough. I have been remodeling my kitchen for the past couple of years doing all of the work myself. Have gotten through all the mechanicals (plumbing, electrical, heating, lighting), brought the walls and ceiling back up and have finally painted and am ready for my floor.

The room is 12 x 17 with 2 x 8 sistered joists running across the length of the 12 ft span at 16" o.c. I have 1/2 in. of plywood down now. I will be using 3/8" 13 x 13 glazed porcelain tiles.

Based on what I have learned, I will need to put down at least another 5/8" exterior grade plywood to bring the height to 1 1/8". With 1/4" backerboard this will bring the total height of my kitchen floor at least a 1/2 inch higher than the adjoining living room wood floor. Now this is without taking into account the thinset underneath the backerboard and under the tiles. Now for my questions:

- Based on recommendations, I will be attaching the second layer of plywood at a spacing of 6" intervals. Thats well over 100 screws/nails per board. Ringshank nails seem like they would be easier/faster to use vs. screws. What do you guys use?

- How much height will thinset add to the floor?

I am considering using Ditra which will help me an lose 1/8" and really only increase my costs by about $50-$60.

I am wondering the best ways to decrease the height without sacrificing a quality install.

- What would be considered too large of a height difference between rooms and/or what is considered acceptable and what would be the best way to handle the transition between the different levels. Sorry for the length of this post. Thanks for all your feedback, it is really appreciated.

Mark