Prepping sand cement wall covering.

[Gazebo]

Morning all,

I have a bathroom to fit and the customer has removed existing tiles themselves to save a few quid, the walls are all brick/block with a sand/cement render then plaster skimm. The plaster skim has come off with the tiles in most areas leaving the cement render on the wall, this is sound in all but a few areas and just feels very dusty on the surface. There are a couple of hand size areas that sound blown or have gone back to brick and also the area around the exisitng bath has gone back to brick.
The walls also need a small amount of levelling prior to tiling

Am i right in assuming i can prime the walls then use a rapid set cement based powdered adhesive to fill any damaged areas and also to take out any minor undulations etc.?

If so should i use Primer g and Keraquik, then keraflex when i tile.?

Or Bal rapidset flexi and sbr then Spf to tile.

Which Ardex products would be suitable in this instance as i have a good local stockist and it seems to be cheaper than some other products.
Wall tiles are ceramic 400x250
Customer also has a glass border tile, will the normal SPF be ok to fix this up.?

Hopefully i am on the right track, just want confirmation on tiling onto sand/cement render and how to patch the walls up.

P.s. dot n dab not really and option

p.p.s. shower is going into a corner and i have have given the customer an option of tanking with Dura wp or Bal wp1, is tanking as important on rendered 4 inch block walls as oposed to plasterboard stud walls.?

Cheers Guys/Gals
Gary

 

[Gazebo]

anyone got any feedback.?

 

[Dan]

Eeeeerm, I'll give it a go. But the lads will need to double check this and respond. I've not fixed a tile for YEARS.

Rather than using any adhesive for patching up, I used to use the dot and dab stuff as that can withstand a thicker 'dot' so to speak. Whereas a tile adhesive can shrink and debond as it cures if it's going on thicker than what it says on the bag.

You could also try 'double tiling' the bits that are deep, back to brick as you say, so you're then using any broken tiles you have around the place to basically stuff in the 'holes' using the correct amount of adhesive on the back of the broken bits of tile. If you need a couple of layers doing this then that's okay but make sure you allow the right curing time between stuffing some more on top - so to speak.

Not too sure on stockists and brands. We're sponsored by Mapei and they provide a technical helpline number - perhaps give them a call? Though all the adhesive companies do, and will help with advice on that front. Again, the tilers on here I'm sure can help once they've had their tea etc.

Now as for the sand/cement render. You might need to check with the adhesive firm you use to get advice on that. You may be able to prime and tile to it using a rapid set. But you may find the skim has come off due to the render being old and loosing it's strength. Obviously if it's really dusty and is coming off in patches it's not safe to tile on no matter what you do to it.

Perhaps getting a plasterer in would save you a few quid in the long-run if you know one or work with one from time-to-time. You don't need the neatest finish if you have dabbled in plastering before, obviously, as you're tiling it. But it does need to be safe and all above board.

Overboarding on old render can still cause problems in the future.

So check the strength of the render showing, if it's okay patch up all the wholes with either the dot and dab adhesive, or double tile, and then if it's all okay check with Mapei tech to make sure you can prime and tile it, I'm pretty sure you can.

But clearly your tiles will only be as stuck as well as the render is stuck to the wall, so if that's all crumbly then the tiles could come off and it might then be down to your own fault per say.

 

[Gazebo]

Cheers Dan
Thanks for the advice, not sure about packing out gaps with broken tiles etc but i can see it would work, will give mapei a call re rendering and tiling, i am sure you can but any other advice will be greatly accepted.

many thanks
Gary

 

[brian c]

use builders fastset to fill the gaps,prime with primer g and then use your KERRAQUICK adhesive.if the walls are really bad then i would consider dot and dabbing some plasterboard.

 

[Gazebo]

When u say builders fastset Brian is that the same as wickes one coat or what is the equivalent in Jewsons do you know?

Do i have to use keraquik or can i just use keraflex.?
obviously primer g in any case.
Cheers
Gary

 

[Dan]

And that's advice from a tiler mate. Clearly I DO waffle after all. 🙂

 

[brian c]

Its up to you what adhesive you use,all depends if you are slow then use a slow setting adhesive such as keraflex maxi.I use the fastset from b and q to fill the voids its only around £4 a bag.

 

[Perry]

If u have small areas that need to be filled just use cement based adhesive and bits of plasterboard to fill the holes when you say blocks do u mean breeze block ? Pete

 

[Gazebo]

If u have small areas that need to be filled just use cement based adhesive and bits of plasterboard to fill the holes when you say blocks do u mean breeze block ? Pete

Hi Pete

yup 2 external walls brick
2 internal walls breeze block of some type, cant see much of it so going on customers say so but defo not timber stud wall.

cheers
Gary:8: