Plaster boards screwed directly to masonry walls - what to do ?

Yes walls are mostly dot and dabbed these days or wet plaster straight onto blockwork, which I think is( far better) than dot and dab, however there is no reason why screwing straight onto blockwork should not be fine as long as p/boards are secure and plumb and there is no movement when plastering.

Never ever drywall screws straight into breeze block, the aerated block construction cannot hold a fine thread screw in any circumstance , under no circumstances is this an acceptable fixing method, dot/ dab is the preferred building industry method or screw 12mm / 18mm OSB onto wall first , then fix plasterboard to that .

Unfortunately the best way is to remove the boards dot and dab them with plaster board adhesive The boards should be re usable You may on occasion screw and fix the the boards after dot and dab this is called secondary fixing and is not normally needed on brick or block work unless they have been previously painted which may cause the plaster board adhesive from bonding to the wall properly

It needs taking off and dot and dabbed properly then plastered I know it's extra expense but at least it ll be done right

The best thing to do is to remove all the plasterboard that have been screwed on trying not to damage them. Then you can dot and dab back onto the walls. If you don't do that then there will be a risk of all your new plaster work cracking

Well, most of the answers above, suggest that you remove the boards and re-fix them properly. And I wouldn't be any different. However, to answer you question if it can be saved then, yes. ONLY IF THERE IS A CAVITY BETWEEN THE BOARDS AND THE WALL You would have to drill some holes (about 6mm dia) along the perimeter (about 3 inches from the edges), and in the middle of the board (randomly) and spray expanding foam into. REMEBER the more you do, the safer the board becomes. FIRE RATED foam on all edges, the rest …. any foam would do. The plasterer then can bond the holes and skim. Before anyone else jumps in conclusions, I had to do this in two separate occasions. oh, I nearly forgot :) There is a plasterboard adhesive in a gun type (like silicone), but this won't expand as good though. Good luck with the project.

It must be removed and redone with dry wall compound commonly know has dot and dabing then scrimmed and skimmed

That’s not correct! As you mentioned they should have been installed using a dot & dab method using plasterboard adhesive. You’ll need to removed boards and reinstall them correctly, otherwise you’re asking for trouble once it’s plastered.