Remove Plaster or Overboard - Solid Walls & Large Format Tiles?

[EViS]

What's the best method for preparing solid walls which have been plastered, ready for tiling with large and heavy stone tiles (e.g. 600x400 marble)?

a) Would you remove the plaster and hope that underneath the walls have been rendered? Otherwise the browning or hardwall would need to come off down to the brickwork/blockwork. or
b) Overboard? In which case would you batten out the walls first, then fix hardiebacker? Or screw hardiebacker directly into the walls?

The second option is going to be more expensive, but will leave you with perfectly flat walls. What's the most common route for you guys?

 

[DHTiling]

You can D&B Marmox boards ( min 12.5mm) and then mechanical fix through the D&B's.. this is good if walls are uneven.. if the walls are flat then you can serrate the walls and then mechanical fix at regular intervals..

 

[Ajax123]

Can you not just dot and dab cement backer board onto the existing and screw through into the structure with mechanical fixings....

 

[Ajax123]

Ahaha...... Dave can type quicker than me it seems

 

[EViS]

You can D&B Marmox boards ( min 12.5mm) and then mechanical fix through the D&B's.. this is good if walls are uneven.. if the walls are flat then you can serrate the walls and then mechanical fix at regular intervals..

Is it merely a preference for using Marmox, or are they in some way superior to the Hardie boards? And as far as fixing goes, would dowel fixings (such as these) be adequate to hold the weight of large heavy tiles?

Can you not just dot and dab cement backer board onto the existing and screw through into the structure with mechanical fixings....

I can, however what is the reason for dot and dabbing (unless the walls aren't flat)? Otherwise you're merely sticking the board to the weak substrate you're trying to get away from? The mechanical fixings will be doing the primary work, no?

 

[DHTiling]

You cannot D&D hardi.. ...

 

[Ajax123]

Based on the recommended shear load of each pin at .15kN each pin will hold 0.015kg.

What weight is your trav??

 

[Ajax123]

You cannot D&B hardi.. ...

Not even if you support it with mechanical so the dot and dab is just to keep it flat and level?? Every day is a school day

 

[EViS]

Not sure of the stone's weight. But 600x400 marble isn't going to be light! I guess that at 20 dowels per board (0.3kg), they wouldn't even hold half a tile :s. If that's the case, and I've just checked the data sheet myself too, what on earth is the use of those dowels/pins?

 

[DHTiling]

The last time i asked Al, Hardi said NO!... but if they have changed that decision , then hopefully someone will say so..

The Hardi 250 can be used on walls but must be fully embedded into adhesive and the hardi 500 is for stud work..

 

[EViS]

Not even if you support it with mechanical so the dot and dab is just to keep it flat and level?? Every day is a school day

I guess that's why you wouldn't use hardiebacker in this scenario .

 

[DHTiling]

Not sure of the stone's weight. But 600x400 marble isn't going to be light! I guess that at 20 dowels per board (0.3kg), they wouldn't even hold half a tile :s. If that's the case, and I've just checked the data sheet myself too, what on earth is the use of those dowels/pins?

You can screw with marmox washers as well.. my preferred fixing method.. and these fixings go deeper than just the base and skim coats.. you plug into the walls structure and if stud wall, then you screw into the studding.. very strong fixings then..

 

[Ajax123]

If you use screws rather than plastic pegs it will increase the shear weight capacity hugely.

 

[EViS]

Sounds like the way forward (i.e. Marmox boards mechanically fixed with washers and screws). Where is the best place to purchase Marmox boards? Do Topps stock them?

As the second alternative, do you guys ever remove plaster from solid walls? Or does this leave the walls too uneven to tile onto?

 

[DHTiling]

PHG Wetrooms , link below.