underlayment, etc questions

Hello

I am looking to put 12"x12" ceramic tile in my bathroom. Joists are 2x10 16" o.c.

As far as subfloor, I have 3/4" hardwood floors that are also throughout the whole house. (Very nice when finished, but not too welcome in the bathroom)

Several Questions:
1) Being hardwood, do I need more subfloor? Or can I just add the 1/4" Hardibacker and be on with it?

2) Is it necessary to add a thin layer of thin set for bedding under the Hardibacker? Or can I just screw it down? (Won't that bond to the hardwood floor making it impossible to remove later?) Note that the floor isn't perfectly flat due to some leftover adhesive from the vinyl flooring and a patch of plywood where we had some rot.

3) Screws or galvanized nails? Does it make a difference?

I'm new to this, so be gentle!

 

(1) Is the hardwood the subfloor? Or is the hardwood installed on top of the subfloor? If the latter, then you're good to go.

(2) Always put thinset under any cement board. Use a notched trowel, probably the same one you are going to use to set your tile. And put a bazillion screws in it too, as recommended by the manufacturer. You need both the thinset and the closely-spaced screws. Hardibacker provides excellent instructions for installation. Follow them exactly.

(3) Hardibacker's instructions allow either. Hardibacker screws are expensive and a lot of work to get seated properly, so you may prefer the nails.

You gave us the size and spacing of the joists, but not the span. Can you provide that?

 

1) Yes, the hardwood is the subfloor...pretty smart, eh? Am I still a go? I won't be offended if not. Oh, the floor space is only 4.5'x6'. Small bathroom.

2) Will do

3) Wouldn't know how to tell you. The whole house is only about 20 feet front to back and I think the load supporting wall is at the halfway spot...So, 10 feet-ish...12 at the outside.

PS The house was built in 1946 and has never had a humidifier, so our floor boards are quite squeaky.

 

Anybody?

 

The span and spacing is ok. Run some screws to fix the squeaks then start the floor.

 

that tongue and groove is more than likly sitting on 1x6 on a digonal being built in 46.you can't just put the t&g on the joists.Use the 1/4 but screw the bejeesus out of it and get screws long enough to get through the 1x6

 

Ok, you guys are going to laugh, but I wanted to post it just for the help of others who might come along later:

When and if you decide to put in a bazillion screws into your hardwood floor, make sure that you know exactly where all of your water supply lines are!

I put a nice long drywall screw right into my hot water supply line. When I backed it out, you should have seen the geyser!

Anyway, it worked out to be a very good thing, in my case, because tearing out the floor to fix the pipe revealed that the previous owner had joined copper and galvanized directly.

The floor is now mostly 3/4" plywood.

That's doing it the long round-about way!