PVA, SBR or BondIt?

[casademont]

I have a brick wall that I intend to install a bath against with a fixed shower head:



I'll use either tile backer board (insulation + cement layer) or hardibacker with a tanking kit; attaching via dot and dab (plasterboard adhesive) and screws + washers to hold it in.

However, what's the best way to prep this surface first? Wash it down and then PVA or SBR? Do I need to scrub and use something like Thistle Bondit instead?

Also any views on merits of hardibacker vs. foam+cement tilebacker board?

Thanks!

 

[Bonni]

Watering down and applying PVA or SBR is purely done to change a high suction background to a low suction backgroud. Most adhesives, plaster etc.. require moisture in order to set. A high suction background (eg. new bare plaster, thermalite block) sucks the moisture out of the adhesive/plaster etc..

Bondit is good to give a good surface for Multifinish.

In bathrooms I've done, I've just dot n dabbed plasterboard, skimmed off and fitted the bathroom suite.