WBP 18mm onto floor boards??

[John the tile]

Hey up

Just looked at a bathroom and the women has got your normal old floorboards down, not chipboard,..


Do these need to be removed to see if there is enough noggins underneath or can I just lay the 18mm straight on top of these? or is it best that there removed altogether...?

Does it have to be 18mm as these floorboards are about 15mm themselves. Could i not put down a thinner wbp ply down, - im gona be using a cement board on top aswell.

Thanks

 

[peteablard]

If there is no deflection then 15mm ply can be used. If there is some deflection then personally i'd lift the floor boards, add some extra noggins and put 18mm down

 

[suave]

if no deflection 6mm hardie backer on top glued and screwed

 

[grumpygrouter]

Yes, agree with Suave. If no deflection then 6mm hardie, if there is deflection sort it first THEN 6mm hardie!!

 

[kilty55]

as above,if deflection free 6mm boards will suffice

 

[John the tile]

excellent.

I have just spoke to my friend and he says hes got to take up all the floorboards to do some pipework etc underneath.

So now Im given the ideal opportunity to get some noggins in to make the floor as deflection free as possible.

So from whats been said above, those floorboards will do the same job as the 18mm wbp ply? From what ive read elsewhere on here its best to use the wbp 18mm then hardie?

Just need opinions as theres more work and expense if I buy a sheet of wbp 18mm. (which i dont mind)

Would the underside of the floor boards needs priming.? What about taping all the joints?

(just to confirm the floorboards are the 6 inch wide ones) Would flexible addy stick to them when putting the cement board down?

Thanks any more advice..

 

[Rich]

Hi mate, In an ideal world, the best thing to do would be to rip them out, lay min 18mm WBP ply and then over board with a cement board. However, if you can get those floor boards deflection free and they are not damaged (damp or rot) then you should be fine over boarding straight over these with a 6mm cement board, I think hardie would be the best bet as they recommend laying the boards over a bed of tile adhesive to fill any voids rather then a gunned in glue.

 

[Rich]

excellent.

I have just spoke to my friend and he says hes got to take up all the floorboards to do some pipework etc underneath.

So now Im given the ideal opportunity to get some noggins in to make the floor as deflection free as possible.

So from whats been said above, those floorboards will do the same job as the 18mm wbp ply? From what ive read elsewhere on here its best to use the wbp 18mm then hardie?

Just need opinions as theres more work and expense if I buy a sheet of wbp 18mm. (which i dont mind)

Would the underside of the floor boards needs priming.? What about taping all the joints?

(just to confirm the floorboards are the 6 inch wide ones) Would flexible addy stick to them when putting the cement board down?

Thanks any more advice..

The adhesive isnt used to stick the boards down, only fill any voids under the boards and then the boards are mechanically fixed

 

[Aston]

if your friend is going to take up all the floor boards, then make sure there is no deflection in the joists and go with rich's advice regarding installing 18mm wbp ply, overlaid with 6mm backerboard etc etc.

the problem you can have with floor boards is...most of the time they are nailed down, not screwed, so there is the possibility of movement.
creaking floor boards = movement! so mechanical fixing and expansion gaps need to be introduced to prevent the possibilty of the installation failing.

 

[John the tile]

perfect, im sorted now. thanks all.....

I just want to ask another quick one.

What size screws e.g how far into the joist should they be pentrating? I was thinking 25mm altogether so 18mm plus 7mm?

Also what type of screws. and would the screw heads needing sealing prior to flexi addy and cement board?

thanks

 

[Rich]

Really as long a screw as you can get away with using without risking screwing through pipes or wires. You can buy ceramic plated screws, these cost the earth but to not rust, as long as you get screws that will not rust, you will be fine

 

[John the tile]

what problem does the rust actually cause?

same screws for the cement board and should these screws be reaching the joists through the ply aswell?

thanks again

 

[Rich]

what problem does the rust actually cause?

same screws for the cement board and should these screws be reaching the joists through the ply aswell?

thanks again

If you are replacing the floor boards with ply then you will want to screw the ply down through the joists at around 200mm centers. If the floor boards are staying then you will want to go round and screw these down to the joists to make sure that there is no movement in them. When it comes to fixing the cement boards down, it is a good idea to screw them down through the joists but if it is over ply then it is not the end of the world just being screwed to this. The main thing is to get the floor rigid.


If you use screws that will rust, they will do... Over time they will begin to rust and this can bleed through and stain the grout between the tiles.

 

[John the tile]

would the rust travel through addy-cement board-addy again then grout?

What are these turbo screws that im seeing mentioned alot from screwfix like? Are they galvanised or stainless steel?

 

[steveboy]

I use the Turbo Gold screws. I think these are the nuts. much better than just say the gold screws.

As for the floor, if the boards aregetting removed anyway I would just ply with the 18mm wbp, seal with BAL primer, if the flor dosent have any flex tile with BAL rapid flex adhesive. If there is flex in the floor then use the backer board aswell.