Using Dot and dab on a lime mortar brick wall??

[liam546]

I'm looking to tile my bathroom with Italian porcelain tiles. The tiles are large and are 90x45 so perhaps heavier than your average tile. Because of this I was advised to remove the old lime plaster which was in places blown as if it didn't the tiles will just fall off.

I've now removed all plaster and are back to solid brick with lime mortar joints. The wall is dusty and has lime on the bricks. To be able to tile I was going to dot and dab moisture plasterboards onto the wall and then afix the tiles directly onto the plasterboard.

However when I called gypsum technical advice they advised me not to use dry wall adhesive on a dusty lime mortar wall as the self adhesive will not afix to lime. Has anyone come across this?? I was advised by them to use battens to afix board too but id like to dot n dab as I think itl be easier.

 

[PrenticeBoyofDerry]

Brush down all the dusty, sandy mortar and masonry.
Then give the wall a wash of water, then prime it with two coats of PVA solution (4 water-1 PVA). Let first coat dry, second coat tacky, then go for it.
Once adhesive has dried, then fix a second mechanical fixing, such as nailable plugs. That should do the trick!

 

[liam546]

Thank you for response. Half the bathroom will be skimmed too, the other half tiled. I'm concerned the nailable plugs may end up proud of the plasterboard making it more difficult as the plasterers trowl will keep catching the nails.

Sorry if there is an obvious solution to this but it's first time of using these and I read somewhere about this happening.

Any ideas?