Subfloor and underlayment questions

I am interested in installing approximately 150 sq ft of 12" ceramic tile in the kitchen of my 50 year old house. I am planning on removing the exsisting flooring down to the diagonal floor boards. The floor boards are tounge and groove and seem to be approx 3"-4" wide by 3/4" thick and are installed on 2"x8" joists, 16" oc and a span of 10'.

Here is my first question. What should be installed ontop of the diagonal t&g floor boards. I am interested in Ditra and the Schluter instalation specs seems to say that ontop of the floor boards shoud be a minimum of 3/8" plywood. Can I get by with just 1/4" plywood? The adjacent floor transsition is old original hardwood strip flooring 3/8" thick ontop of the diagonal floor boards.

Next question. Once I have my subfloor, consisting of the diagonal floor boards plus what ever is recommended complete, should I use Ditra or cement backer board? Ditra seems to be a very good product and I would like to go that way. It seems that most contractors have had good results with it, no?

Any advice would be very appreciated.

Dan

An additional question. If I decide to go with a Ditra installation, can I install it right over the 3/8" strip hardwood instead removing the hardwood and installing plywood?

Dan

Dan,

You need to remove any strip flooring as you implied in the first post. Once you get to the 3-4" t&g plank subfloor, repair if necessary and re-fasten every board at every joist.

If the subfloor is very solid, you may use 3/8" underlayment grade ply. NO cheap CDX stuff. I recommend 1/2", the more the better. You will save thickness by using Ditra. Quarter inch plywood is not for a ceramic installation as it adds little or nothing in strength. You can't have all rooms the same height unless you install the same flooring in all rooms.

Jaz

Thanks for your advice Jaz. My research tells me the same.

What do you mean by "cheap CDX stuff"? I am not familiar with the different kinds of plywood. If I want 3/8", what type specifically should I be asking for at the lumber yard?

Also, any trick at removing old hardwood? I am planning on cutting to the same thickness with a circular saw and then prying. Sound right?

I used a circular saw to cut the edges of my foyer hardwood floor and used a pry bar to remove the wood. The saw could not cut right up to the wall so I used a drill and drilled several small holes. I then used a wood chisel and hammer to get the pieces out.

The 3/8" plywood underlayment you want to ask for is a BC or AC grade. No CDX sheathings.

Jerry

Thanks for the replies!

Dan