Tanking straight to sound finish plaster

[solddowntheriver]

I am almost at the point of re tiling my bathroom and have a couple of minor dilemmas that are bothering me before I start.
The first is this, having painstakingly removed the old tiles I find the walls are plastered to a very good, true and even finish, now I want to use a tanking kit around the separate shower (enclosure) and around the bath.
My dilemma is this, should I use backer board as an add on to the already plastered walls or is having a decent plaster finish good enough to tank too?And if plaster is ok to tank directly on to should I do anything to it before the tanking kit is used?
Dilemma two is this, if backer board is to be used I will have to back three walls in their entirety as the ceiling height is over 2600mm and "backing" just in and around the shower will create a lip past the shower! As well as adding serious cost to what started as a weekend special is now turning into a monthly monster job!
Any thoughts would help.

 

[tpt]

Hello, if you already have plaster, then tanking it will be fine.

What type\size of tile are you fitting?

 

[solddowntheriver]

The tile size won't be big, probably 400 x 250 ceramic max.

Also if I have to board out the walls surely I would have to "tank" the edges and corners anyway with board? Does the board attach over the plaster and is it screwed to the wall? (mine is a brick wall.)

Thanks for taking the interest.

 

[tpt]

Hi There,
backerboard can be used onto timber frame or solid walls, no need to tank, just tape the joints.

Tanking is used instead of backerboard in order to create a waterproof background. With those size tiles you should be fine with tanked plaster and tiling onto that

 

[solddowntheriver]

thanks for the reply. Tanking kit now ordered