Hi all.

Got a job where I'm tiling 600x300 porcelain over different subsrates. It's an extension and the extension has 18mm chipboard screwed down to joists and then just before the extension is a solid floor section about a metre square and then just behond that are floorboards screwed down to joist. Didn't really want to have expansion joints both sides of the solid section as it would make the tiling work very ugly so was thinking about 6mm cement boards over the whole lot and then tiling. Is this ok in your opinion?? Cheers

hi cc
you really need an expansion joint where 2 substrates meet.
cement boards wont add what your looking for. if theres any stress, it wil still force through.

ed

Originally Posted by AstonTiling

hi cc
you really need an expansion joint where 2 substrates meet.
cement boards wont add what your looking for. if theres any stress, it wil still force through.

ed

Is there no way around not using expansion joints. the solid section is right where you walk into the room so you would walk in with to joint either side staring you in the face!!

you could use a matching silicone. that wouldnt be quite as noticable as an expansion trim but it would be wider than your grout line, so your its your call really mate.

Originally Posted by AstonTiling

you could use a matching silicone. that wouldnt be quite as noticable as an expansion trim but it would be wider than your grout line, so your its your call really mate.

Yeah that's what I would've done mate but it's gonna be half bond 600x300 so that wouldn't work

It is a pig but there isnt any other way round it (that I know of), I seem to be getting it a lot lately with random pattern floors.

How wide a joint are you going to use? Is there no way of incorporating the joints into the pattern?

Originally Posted by Rich

It is a pig but there isnt any other way round it (that I know of), I seem to be getting it a lot lately with random pattern floors.

How wide a joint are you going to use? Is there no way of incorporating the joints into the pattern?

The tiles will be running in the opposite direction to the split in substrates and even if they were the chances of getting it to meet in 2 places is pletty slim. Floors gonna look crap with 2 expansion joints a metre away from each other!! There's gotta be something I can do

BATEX1_tif_160x600_q85.jpg


might help

You could make sure that any deflection at meeting points is ZERO.. then you only have differing lateral expansion.. and an uncoupling membrane will suffice.. not 100% Bs guidelines but a compromise,., sometimes staggered breaks in substrates cannot be expansion jointed.. so cutting out deflection is an option ..

Originally Posted by Dave

You could make sure that any deflection at meeting points is ZERO.. then you only have differing lateral expansion.. and an uncoupling membrane will suffice.. not 100% Bs guidelines but a compromise,., sometimes staggered breaks in substrates cannot be expansion jointed.. so cutting out deflection is an option ..

So would you recommend cement board then uncoupling membrane?

A board like marmox would be my choice, 10mm board then uncouple, overkill but better to make sure

Ok thx Dave

Could I just run membrane on the solid section and past the difference in substrate join about 500mm so I don't hae to spend out on 20m of membrane!?