Shower installation advice

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 can't slip.

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.

Thanks for the useful tips, John

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 slide about.

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.

Dear Kent 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 often develops.) 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 the BRE) Chris

Hi kent,

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 the future.

Ian