Tiling Onto Timber Floor With 4 Inch Joists - Tile Advice

[ajc]

I'm intending to tile a kitchen diner floor, 1/3 of which is concrete but the other 1/3 a suspended timber floor on 4 inch joists. I'm aware that such joists have a propensity for deflection/bounce, which I need to remove. My intended plan of action is to remove all the floorboards and replace with 25mm plywood 8x4 sheets. I'll also put 2x4 or 3x4 supports at regular intervals between the joists, and build some dwarf walls beneath the joists to add extra support ( the joist are suspended about 1 foot above the foundations).
I'll then plan on put matting down over whole floor (ideally the bal matting as its only 1mm thick and thresholds are an issue).
Do people think this is okay, or should I put 6mm no more ply down instead of matting to add extra strength? And is my plan for reinforcing the floor adequate?!
Thanks.

 

[mattle40]

Ur taking the right steps, personally I would go for a cement board too though such as hardi or no more ply. Hard to say without seeing it however.

 

[CJ]

22mm T&G structural hardibacker.

HardieFloor Structural Interior Flooring 500 x 2400 x 22mm

 

[ajc]

22mm T&G structural hardibacker.

HardieFloor Structural Interior Flooring 500 x 2400 x 22mm

Will that be stronger do you think....even though there will be more joints?

 

[Rizzle from the Portizzle]

ok 1/3 of the floor is missing but your build up and surport is all going the right way .instead of using 25mm ply use two 12.5 mm ply sticking and cross bonding and scewing down .that way you leave no running joints .blanke permamat will allow far more defletion all ways as you are joining a solid floor to a moving floor so you need to allow for the up and down movement .as well as left to right .and a 1mm mat nor ditra will allow for this sort of movement .

 

[ajc]

ok 1/3 of the floor is missing but your build up and surport is all going the right way .instead of using 25mm ply use two 12.5 mm ply sticking and cross bonding and scewing down .that way you leave no running joints .blanke permamat will allow far more defletion all ways as you are joining a solid floor to a moving floor so you need to allow for the up and down movement .as well as left to right .and a 1mm mat nor ditra will allow for this sort of movement .

Hi Ray,

Thanks for that. 2 layers of ply cross bonded sounds a great idea....shall I screw the top board all the way through to the joists or just into the bottom layer? And do I glue them using a wood glue or a 'no more nails' type thing like sticks like s**t?
And then do I put the blanke permat on top too....and where do I get that from, when I googled it all I could find was sites in the USA?!
And then matting ontop of that too or not?

 

[Rizzle from the Portizzle]

screw the first layer down the soak with wood glue then lay the next into it cross bonding then screw down again when the glue drys re tighten screws you now have a ply base at least twice as stronge for tiling than a single layer of 25 mm put the blanke permat on top belts and braces all the way .trimline sell blanke permat

 

[ajc]

screw the first layer down the soak with wood glue then lay the next into it cross bonding then screw down again when the glue drys re tighten screws you now have a ply base at least twice as stronge for tiling than a single layer of 25 mm put the blanke permat on top belts and braces all the way .trimline sell blanke permat

That's really helpful, thanks. I've just registered with trimline so once they've verified me I'll be able to get a price from them.
2 more quick questions if you don't mind:
Can I lay the permat onto the concrete part of the floor and the plywood using flexible tile adhesive?
And really daft question....is there a brand of wood glue you use or can I just go to screw fix to grab some standard s
Thanks for your time

 

[Rizzle from the Portizzle]

yes you can. pva will do but the black one its water proof

 

[Unused Account 1]

yes you can. pva will do but the black one its water proof

Great info ray ,ply been used as long as remember

 

[mattle40]

im sure you know already but didn't want to assume, you will still need a movement joint in the tiles.
Unless permat is capable of bridging sufficiently? But I'm sure Ray will clear that up.
Apparently it can but I'm always dubious of such witchcraft.

 

[Rizzle from the Portizzle]

im sure you know already but didn't want to assume, you will still need a movement joint in the tiles.
Unless permat is capable of bridging sufficiently? But I'm sure Ray will clear that up.
Apparently it can but I'm always dubious of such witchcraft.

well heres a couple of pictures of a test i put it throught you will have to make up your own minds how much movement you think you will have

 

[Rizzle from the Portizzle]

PS if you line your grout join up with the two floors this will give you even more movement scope