remove old floorboards, replace with 18mm ply then tile? - Tile Advice

[vinnie]

Hi,
I am laying a kitchen floor and hallway soon. The problem I have is 3/4 of it is wooden floorboards then the other 1/4 is concrete,they both meet level.
My question is rather than board it all out can I remove the existing floorboards and put down 18mm ply and screw to joists. This will then make the whole of the floor one level again. I was wondering if just screwing to joists and noggings will it be enough to stop the wood from flexing?
Would this then be ok to tile over using flexi addy and grout? and tile the concrete as normal, obviously priming all boards and concret beforehand?
Hope you can advise,many thanks,
Vinnie

 

[macten]

You really would be best overboarding any wooden substrate before tiling.
My chosen method for this scenario is
1. take any movement out of floorboards
2. overboard with 6mm cement board
3. SLC concrete flush to board height
4. Anti frac membrane covering transition (500mm either side) Mapetex guarantee this method.

 

[vinnie]

You really would be best overboarding any wooden substrate before tiling.
My chosen method for this scenario is
1. take any movement out of floorboards
2. overboard with 6mm cement board
3. SLC concrete flush to board height
4. Anti frac membrane covering transition (500mm either side) Mapetex guarantee this method.

Thanks for that Macten,

If I used 6mm backer boards can i just bed them down in adhesive instead of screwing them and just tile to the board?
Thanks,
Vinnie

 

[macten]

Bed them in AND screw. The addy's job is to fill any voids and the screws for the actual fixing:



I find the 25mm gold turbo screws from screwfix are excellent. 25mm means you won't risk hitting pipes and cables. A box of 200 will fix about 5 1/2 boards

 

[vinnie]

Bed them in AND screw. The addy's job is to fill any voids and the screws for the actual fixing:

View attachment 94128 View attachment 94129 View attachment 94130

I find the 25mm gold turbo screws from screwfix are excellent. 25mm means you won't risk hitting pipes and cables. A box of 200 will fix about 5 1/2 boards

Thats great Macten,
Thanks so much for your help

 

[Old Mod]

A bit late to the party, but James Hardie make structural flooring 19 & 22mm in thickness. It can be screw straight to joists and really is a good product. Just used it recently and I was surprised at its stability. It’s very good.
You can remove the floor boards, fix the Hardie Floor in its place and just latex the two surfaces level if necessary.
Then you won’t have any worries about the timber side of your floor deforming and causing problems down the line.
Depending on where the floor transition is, you could either follow Nicks advice above, with the mapetex or have an expansion joint.
And before I used Hardie floor, I expect I would have used a similar method to Nick.

 

[rieveleyceramics]

Similar to 3_fall I use cement fibre boards such as Hardie backer in preference to plywood on suspended floors as they provide a more stable base and are less subject to breakdown due to environmental factors such as moisture. As most of the work I do is restoring Victorian tiled floors it is not uncommon to come across the cement substrate on suspended floors which tiles have been laid to have broken down with the result of loose tiling and collapsing floors. In many cases the original tiles can be reused but the substrate which is basically made up of cement mortars needs to be replaced. The standard practice when these floors were laid was to board in between the joists and put a weak mortar layer of around 1 inch depth upon which another stronger mortar layer was placed in which the tiles were set. As these floors have been in use for well over a century the flex that is inevitable on a suspended timber floor and the brittle rigidity of the mortar overlay, the continual traffic over the years leads to the eventual breakdown of these floors.
So replacing with cement fibre boarding of appropriate thickness ensuring that it is screwed firmly to the joists at least as at the distance points as specified by the manufacture and using a flexi adhesive should ensure that the replaced tiling has the chance of being in place for another century.

 

[Simonmiller]

I have replaced my old floorboards which were rotten and damaged for 18 mil ply tongue and groove can I tile straight on top of it or do I need to add an additional layer Of plywood