Tiling over plasterboard

For wet areas (i.e. in range of showers) use aquapanel or rendered WPB ply. Fo other less critical areas you can give plasterboard a coat of PVA and tile straight on to it.

If the bath is used as a shower, aquapanel might be a good idea but, if it means putting it over existing PB and raising the level around the bath, I wouldn't bother. IIRC it only comes in 4ft square size (which is about all you can lift easily). Focus do it I think

I have simply tioled over plasterboard straihght, and have showered regularly dowsing teh tiles ever since.

After a year its still spot on perfect.

Only in the case where water can collect and permeate through grout and into the plaster, and fester there, is there an issue, I feel.

Use a decent waterproofish tile cement - I used Evostik something or other

- and possibly maix PVA or other additive to the grout to render it if not waterPROOF at least relatively impermeable.

I think use aquapanel if not tiling.

But the reasons one uses tiles is because they are - er - waterproof.

Two waterproof layers don't really keep out more water than one, in my experience..

Absolutely, but if the 'top' layer fails or develops a leak for any reason, at least the underlying aquapanel stays intact and doesn't collapse like plasterboard does. I also feel aquapanel is inherently best in this application because it's really rigid, and has much less tendency to flex than plasterboard (thereby cracking the adhesive joint).

It's a 'belt and braces' approach I suppose; but for the small extra cost I personally feel it's worthwhile.

David