I'm installing a shower for the first time and would be grateful for
some advice from you more experienced people if you wouldn't mind.
Simple questions, I think:
1. If I put down a stone tray onto a suspended floor, with enough
room for the waste, could I put down a sheet of reasonably thick
polythene and put the bedding mortar on this or is it necessary to use
2. Can I tile directly onto skimmed plasterboard or do I need to use
Many thanks for any answers.
You could, if the boards are securely screwed down. I'd screw though the
poly too, or staple it down or use double-sided tape so the tray+bedding
FWIW I use one-coat plaster rather than mortar for bedding: it can be
mixed to just the right squishable consistency whereas mortar tends to be
too stiff to allow fine adjustment of level when bedding the tray.
WBP or marine ply, or aquapanel or Marley or other equivalent cement-based
panel is much better. That way your tiling (and grouting) doesn't have to
be 101% perfect in holding back the water.
Do take care to seal the gap between the edge of the tray and the wall.
Silicone is the usual stuff but I've recently used Toolstation's 'Stixall'
(similar to Evo's "Sticks Like Sh*t") for this job.
Who's *really* behind all these conspiracy theories?
If the boards are solid and do not flex too much then you can. You would
need to fix the membrane such that it does not allow the whole lot to
You can tile straight onto un-skimmed plasterboard if you want. However
I would not do it for walls that are actually in the shower enclosure,
since the slightest leak will cause major damage in very short order.
I endorse the advice of the others and add that Wedi board
(HORRENDOUSLY expensive) is an alternative to the cement-based board
and inherently water proof.
The junction of the tile with the tray is crucial. Make sure that the
tray is abutted up to the studding or the wall surface and if
possible it it is a plastered wall remove the plaster at the bottom
just sufficiently to get the base of the tray just under the outer
edge of the shower so that if the tiles fail or the joint fails the
"default" route for the water is from the original wall to the tray
not outside the edge of it. I get a lot of business from showers that
are not so installed and allow water to drip on the outside. (Dry rot
Bed the edge of the tray if possible in good quality mastic as it
abuts the wall and alllow a suitable detail or appropriate extrusion
for the abutment of the tile with the shower tray. Remember if you are
doing this with mastic to make it at least 10 mm deep and thick.
(Mastic needs an appropriate volume to work - see DAS 68 and 69 from
Have you considered using something like Showerwall in place of tiles, and a
shower tray with upstands?
That should solve a lot of potential future problems, and save you the
problem of the grout looking dirty and potentially failing at some time in
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