I have ordinary plasterboard in my shower & was going to tile directly onto this using waterproof adhesive & grout. Does the board need a plaster skim or just prime it. What primer would you use. T

whats it with all these My builders tellin there customers to PVA before tiling!! Its not compatible with either tubbed or cement based adhesive as it breaks down in the presence of water and creates a weak bond!

If its not possible to change to boards, then you want to 'tank' the shower area. Paint-on or membrane types are available & easy enough to apply. Priming - each adhesive is different, instuctions on the packet should tell you if they recommend priming or not. & if so, the manufacturer will probably have a compatible primer. Tile adhesive depends on the type & size of the tiles you are using. If possible you'd be best avoiding any tubbed stuff... and if its ready mixed adhesive & grout in 1 - then take it back, and do more research on suitable adhesives. MW Tiling.

you must tank the shower walls or it will leak!! ply is also prone to problems in wet areas as it expands and contracts with moisture content changes. The best background for shower is wedi board or marmox board it will never rot or twist and is waterproof not just water resistant

No plaster skim is required. A plaster skim reduces the permitted weight to 20kg per square metre.

Tanking will probably cost nearly the same as replacing! Plasterboard WILL break down in a couple of years at best...then you have the additional cost of re-tiling, and probably replacing the tiles! I'm sick of following people that didn't...and the there's the ceiling down stairs...and the joists are rotten. seems cheap at the time! Strongly recommend Hardi-Backer!- Sika-bonded to the tray!...and fully bed the tray! Regards Simon

Marine ply would be the best option 12mm but you can pva the walls first

Pva is enough than use normal wall tile adhesive Hope this help