Hi, I've read your advice about not using PVA onto plasterboard before tiling due to it leaving a thin layers which will be all that hold the tiles in place. Unfortunately I only read it after my plasterboard had a coating of PVA on it. I wonder what your advice would be regarding fixing the problem before I start tiling.
Thanks in advance.
Some tilers will tell you you can tile direct onto PVA and do it as a matter of course. The manufacturer of one of the cheap tubbed addys (available from Bargain and Quick) says use it.
Several of the specialist adhesive manufacturers say its a No No and I trust their advice. I've seen a load of tiles fall off a wall that was PVA'd first (no it wasn't me that did it!) and have found tiles that were still up but hanging on literally by the grout on walls that had been PVA'd. Thats why I say don't do it. I'm not about to have them fal off when I was paid to put 'em up in the first instance. Just to put in in perspective before someone comes along and contradicts me.
Anyhow to remove the PVA you'll find that some hot water and elbow grease should shift most of it. A bit of a sand afterwards should deal with what's left.
My adhesive certainly recommended it for porous walls. It sealed the dust nicely on my kitchen walls where the builders had riped the old tiles off rather heavy handedly, but on rough walls I'm hoping there will be enough for the tiles which are already in place to keep gripping too.
I'll be taking the PVA off the plasterboard before tiling though, better safe than sorry.
Oh certainly use it on brick/blockwork before plastering and plaster before it dries. Should not be used on plasterboard before skimming hough and never (IMHO) before tiling.
Be careful not to degrade the surface of the plasterboard. Actually if you are using an adhesdive that says use it then why remove it? Go ahead anyway and if they do fall off you can take the manufacturer to task.
Bit of a risk but you DO have a fallback position in case of problems because you were following manufacturers instructions.
not normally necessary to prime raw plasterboard as it's designed to take a finish - be it a skimming plaster or adhesive (provided the surface of the board is dust-free and you are tiling onto the correct side of the board). only needs a sealer if the plasterboard has been skimmed.
anyhow, as rosebery says, if you are following the manufacturers guidelines then you are covered.
I tried scrubbing the PVA off the plasterboard but it just started taking the paper off instead so I stopped. The instructions on the adhesive (I had a tub of fix and grout sitting around) said to use PVA for porus surfaces so that's what I've done. hopefully the tiles will stay in place but if not it's just for a utility area in the garage so no great harm done.