Hi, I've gutted my bathroom in preparation for a new install. This included stripping all the old tiles off the wall and chasing in new pipework which has left a less than ideal surface to work on. I've removed as much of the loose stuff as possible but i'm un-sure what to patch and repair with. The worst wall is external and breeze block and has a soft grey finish which i believe to be a render?? (grey in colour and up-to 20mm thick) its damaged from tile adhesive removal, crumbling and powdery in places, probably the original finish from when the house was built (70's built). Can you advise what would be suitable to use to repair the holes and damaged areas before i plaster. I've used bonding before for minor repairs etc but i'm concerned mainly for the adhesion as whatever goes on the wall will need to take the multi finish plaster and / or tiles.
Thanks in advance,
Kris
Answer
Hi Kris
The best plaster to use would be 'Bonding Coat' due to the fact that it sticks so well. This will also provide a good key for both tiles and multi-finish plaster.
The old plaster could be render or "Bonding Coat' or 'Carlite Browning' as depending upon where they were manufactured could be either pink or grey in colour.
Either way, all of them can provide high suction, and as you may have areas of loose and dusty plaster it may be worth first applying a coat of diluted PVA (milky consistency).
Then a thin smear of Bonding Coat pushed in everywhere, is crucial to ensure a good bond is obtained before applying any great thickness.
This will give you a strong well adhered base coat.
Paul