Setting Out Newbie's Questions

[Aspesim]

Stupid newbie here!
What does tank mean (in relation to installing new plasterboard or Tile backing board)
Why do you need to scrim (is this adding tape to the joints and plastering over)
Why do anything to the joints if you are going to add adhesive and tile over

Simon.

[aph257]

To tank means to fully waterproof the substrate i.e. wall or floor. tanking would negate the need to scrim the plasterboard.

[Stewart]

Tank means to put on a waterproof membrane to protect the substrate and stop moisture passing through. You can scrim or tape backer boards such as Marmox to make waterproof in wet area's and there's no need to scrim any joints out-with a wet area imo, although I do scrim Cement boards on the floor for added stability.....

[akinsontiles]

The reason for scrimming joints in plasterboard or cement board is purely for a "belt and braces" effect. If the joint is weak it may move and cause the tanking system to rupture. However if the scrim (plasterboard style) is reinforced with jointing compound then it offers a more solid surface to trust the tanking liquid onto.

You could also you a cement based non adhesive for this but it may suffer from slumping and be rather messy if you don't fancy getting the jointing compound and have adhesive on site.