1st Job: Best substrate over floorboards for floor tiles?

[coldickey]

Evening all,

I have read many reviews, forums and discussions on the internet about what the best substrate is for tiling on.

I will be tiling a bathroom floor of approx 8m2. My house is over 100 years old and I suspect the floor boards also are. The floor boards seem quite sturdy.

I believe the best method would be to ensure all floorboards are secured and lay plywood (maybe 12 or 18mm) on top of the floor then lay 6 or 12 mm hardibacker board on top, all screwed into the joists at 300mm intervals.

doing this will increase my floor height by too much, so I am thinking that if I do a good job securing the floorboards and ensuring minimum deflection (add in some noggings) then I will be ok to just lay 12mm Hardiebacker board screwed to the joists, then tile on top.

Does this sound ok?

If I choose this method, what type of adhesive should I use. flexible?

Yours thoughts would be appreciated.

Thanks

[whitebeam]

I'd be using 6mm hardie backer boards personally

[Bri]

If you can, replace the floorboards with 18mm ply (add some noggins while you've got the boards up) stick down a 6mm cement board with flexible tile adhesive and screw it also, then tile. Welcome along to the forum.

[Stewart]

If you get the board solid with no deflection the fix 6mm backerbord with SPF addy and screw every 200 mm.

[Mike]

as with bri on this one. even if you screw all the old boards down there would still be too much deflection to just put backerboards on

[whitebeam]

This house is a 100 years old.

[coldickey]

Thanks for the quick responses.

My issue with replacing the floorboards is that I don't want to make any changes to the bath area of the room (due to tiling and fittings already in place) and so am unable/unwilling to change the floorboards if they also have to be changed.

Is it possible to change some floorboards with plywood and leave the ones under the bath as they are? I guess it depends on where the joists are and how the boards are laid.

[Phil Hobson]

If you can, replace the floorboards with 18mm ply (add some noggins while you've got the boards up) stick down a 6mm cement board with flexible tile adhesive and screw it also, then tile. Welcome along to the forum.

I would think this would be the best option, backer boards don't do much to help eliminate deflection. Glue and screw every time

[doug boardley]

I'd be replacing the floorboards with minimum 18mm ply and using hardie 250 as an overlay