How to deal with high suction walls?

[jayc89]

We have a room where the internal walls are back to brick. We previously had similar walls in other rooms plastered using bonding followed by multi-finish. Where this has been done, there are quite a few nasty cracks, which we've been told are down to the suction not being controlled properly (they don't look structural, at all).

 

I will be getting someone else in to do the plastering. I've heard of using PVA, hardwall, slurry mix, sand/cement etc. How should I be asking them to tackle these walls?

[Declan52]

Wet the walls first then it won't suck as  much out of the plaster. And I mean wet not just a tiny bit damp.

[SimonD]

I've used hardwall plus multifinish on high suction clay bricks. DIY and no cracks. The way I approached it was to liberally spray the bricks with water, let it soak in and then spray again before applying hardwall. With the hardwall, I keyed it and left to set, then wetted and applied the multifinish24 hours later. No need for pva or anything like that, just hardwall and multifinish.