not sure if this is a flooring question?

[slothrop23]

Hi peeps. i am sorting a floor in my flat which was a bedroom and is now going to be a bathroom. basically i have levelled and boarded the floorboards with 12mm plywood. i am going to seal the boards with wickes tile primer and admixture and use wickes rapid set tile adhesive. is this going to be o.k?
my main concern is that where the basin is is a big rectangle of ballast cement mix the waste run has been drilled out of the ballast. i have used a cement powder to fill the hole but have run short. i have a little left but about a litre less than i need. can i mix in some finishing plaster to top it up? would that be strong enough?
many thanks in advance, and sorry for my ignorance

 

[dispatch19]

hi make sure your plwood is well screwed down to subfloor if the floor is concrete you will need to lay a damproof membrane you can coat the plywood in pva 3;1ratio and make sure your tile adhesive is flexible or tiles will pop off after a couple off months if your adhesive is not flexible you can mix it with latex solution and that will make it flexible if you use a dark grout you will probably get white marks coming through grout after a few months this is caused by the latex in the tile adhesive bleeding through but if you scrape the grout it will assily come off regarding the hole you should use concrete or mortar plaster will just absorb any damp in floorand could cause you problems later on hope this helps