floor and wall prep

[stuartavo]

always had good advice here so before i make a mistake i have 3 questions.

before the wbp ply goes down on new joists do i have to seal/prime itand the edges.

when the floor goes down do i prime it,seal it before tiling.

lastly ne w multi finish plaster ,can i tile straight onto it or do i prime it/seal it.

what products do i use. (i have bal sbr here).

appreciate your advice stuart

 

[Barry bp]

seal back and sides of plywood how thick by the way
and sbr on plaster they say not to prime top of ply now

 

[nybor62]

what size tiles do you intend using on skimmed walls , are they ceramic . porcelain , or stone

you dont want to be putting more weight than the walls can take

 

[merlecollins]

Hi Stuartavo,
Firstly lets just make sure of something - what thickness ply are you putting down? are the joists you are fixing it to solid with no bounce?
Only seal the back and edges of the ply - me personally I would fix Hardie Backerboard over the ply as well for a belt and braces job, but this is not always necessary:smilewinkgrin:
I always prime plastered walls with Mapei Primer G before fixing with P9 or Keraflex How long have the walls been plastered? Before fixing to plaster skim you need to make sure the weight of the tiles, adhesive and grout does not exceed the recommended weight.

 

[White Room]

If you prime the new plaster with sbr thin down 3-1

 

[stuartavo]

ply is 3/4 ply screwed down onto new joists.fixing travertine and have done the calculations and i dont exceed the weight per metre.plaster is new.just dried out by the way.

 

[stuartavo]

forgot to say no bounce and solidly fixed to joists

 

[merlecollins]

OK - in your situation I would be overlaying the ply with Dural CI matting. But I cannot emphasize enough - you must make sure there is NO deflection in the ply first.

The trav is a soft stone and will crack along the joints of the ply with expansion. The CI matting will eradicate the chance of any cracking coming through to your tiles

 

[stuartavo]

getting back to what i asked initially what do i prime the ply with?.sbr diluted on the walls?.

 

[merlecollins]

getting back to what i asked initially what do i prime the ply with?.sbr diluted on the walls?.

Walls.
You will hopefully be using cement based adhesive, so you will need to dilute the SBR 2 parts water to 1 part SBR and apply 2 coats
Ply.
Undiluted to the back and edges of the ply

 

[stuartavo]

gonna use mapei keraquick

 

[merlecollins]

gonna use mapei keraquick

On the floor. Are you using it on the walls as well?
Don't forget the CI matting mate.:smilewinkgrin:

 

[stuartavo]

keraquick and kera quick maxi.whats ci matting fella.

 

[White Room]

dural ci matting - Web search - Virgin Media

 

[merlecollins]

keraquick and kera quick maxi.whats ci matting fella.

Important for your job:smilewinkgrin: