Flooring Tile - Installing tile in bathroom

I have a fairly small bathroom that I am going to install porcelain tile in. Its an older house. The subfloor is actually boards, no plywood. Looks like honest to God 1 by 6s. Not todays 1 by 6. I plan to use some form of backer board. Should I put down a thin piece of OSB first to give myself a nice level surface? Then thinset and then the backer board? Thanks

You cannot install cement board over the planking. You must install a minimum 1/2" of plywood over the planking first. You could use osb instead of plywood, but plywood would be better.:)

Thanks for the reply Johnny. Thats what I thought.

Johnny,

let me ask you this. What should I do as far as installing the plywood to the planking? Nail or screw it down or nothing? I know I will be putting a layer of thinset down under the backerboard and screwing it down with proper screws to the plywood. Should I make sure the planks are good and tight with the joists as well? Should I try to have my backerboard screws hit the floor joists? Do I need any kind of membrane or is that taken care of with the backerboard? Thanks!

Should I make sure the planks are good and tight with the joists as well?

Yep, add as many screws as need be to make it as solid as you can.

As to the plywood, it should be exterior glue cc plugged or better. Plywood gets installed perpendicular to the joists. Leave approx 1/8" between sheets for movement. You can either fill the gap with cheap caulk or just leave it alone. Use deck screws long enough to go about 1/4" or so through bottom of the the plywood and the planking. The idea is to screw the plywood to the deckboards, not the joists. Use screws every 8" in the field and every 6" at the plywood edges.

Should I try to have my backerboard screws hit the floor joists?

As to the cement board, it gets bedded in fresh thinset using 1/4" notch trowel. Use the screws that specially for cement board. Same here, screw into the plywood and avoid the joists. Similar screw pattern as the plywood. Read the installation instructions for whatever cement board you decide to go with and follow them to a tee.

Do I need any kind of membrane or is that taken care of with the backerboard?

Its either cement board or membrane, not both.

Thanks!

You're welcome:)

Johnny,

thanks again for the great information. Here is what I have discovered tonight.

Under the vinyl tile in there, there is a layer of hardwood planking 1X6s at least 1/2 thick on top of the planking laying on top of the floor joists. Very smooth tight fit. They run perpindicular to each other. Would it be best to rip those up and put down the plywood or could they be used instead of the plywood? What type of screw should I use either way?


Ok regardless of the answer there, once I put down my thinset mortar and screw down my back, how long before that can be walked on? Im thinking that if I am screwing this stuff down, its going to be down tight already so it can be walked on but Im guessing.


Thanks again for your great help!!

Scott

You need something stable under the cement board. The second layer of planking has to go. Replace it with plywood, 1/2" or better as described above.

Once you install the cement board, you can walk on it right away. I assume you are asking this question because you want to get to work right away installing the tile, yes?:D

Johnny,

do you thinkit would be better to use something like Flexbond instead of Versabond for my thinset? The Flexbond costs about $30 for a bag compared to $13 for the Versabond.

Versabond is a low end modified thinset. I know a lot of people that use it successfully every day though. Yes the flexbond is a better thinset and a better choice in my opinion.