Bedding in a stone shower tray

Discussion in 'Plumbers' Talk' started by doggy1970, Aug 12, 2017.

  1. doggy1970

    doggy1970 New Member

    Hi all, need some extra advice here.
    Just bought a stone resin shower tray and Im fitting it onto 18mm marine ply that has been sealed with PVA.

    I spoke to the manufacturers about bedding it in. I believe a lot of people use some kind of mastic although it will void the warranty.

    I've been told to use a weak sand/cement mix 5:1 and its to be semi dry.
    I'm worried if it's to wet it may damage the hardboard, am I worrying too much?
    Also the instructions speak of anti crumble additive, again I've been told to use PVA or washing up liquid, what do you thnk?

    cheers in advance.
  2. fillyboy

    fillyboy Active Member

    I've always been a little puzzled as to why the manufacturers insist on a continuous bed of mortar otherwise the warranty will be voided, alternatively,
    they're happy to supply a plastic leg kit without voiding the warranty. Don't make sense.
  3. DIYDave.

    DIYDave. Well-Known Member

    Only diy myself but I have fitted a few of these stone resin trays

    Always follow manufacturers instructions and file all the paperwork should you have a warranty claim down the line - it's not totally unheard of for these trays to crack :eek: although usually down to poor installation

    Yep 18mm ply very good, screwed down to existing floor I take it and all rock solid with no movement ?

    SBR would have been better to use as a sealant as PVA can become tacky again if it gets wet. Can't see it being a problem though and as for the water in the mortar damaging the ply (it's not really hardboard is it) you've got no worries here - calm yourself down. The water content in a semi dry mix ain't that great and will evaporate away as the cement cures. Marine ply is great at shrugging of water and, this is just a once in a lifetime wetting, as with careful and correct installation of the shower and fittings, it ain't ever getting wet again in its life .... :)

    The anti crumbling admix is more usually referred to as 'plasticiser' and makes the mortar easier to work with, trapping air in the mix and giving a soft butter like consistency. Also a little frost profing and other benefits but no biggie here with ur shower tray

    Some peeps have / do use a small squirt of wash up liquid in the water for the mix as again helps with the consistency and helps in levelling. Certainly not worth buying 5ltr of plasticiser for this 1 off job so either leave out or maybe a splash of fairy (not sure if there are any adverse effects of using a detergent)

    Anyway, make sure the timber is all rock solid and lay a solid base of mortar. Level mortar, check in all directions with a long level then bed the tray, check levels and some pressure to bed in - with a dry ish mix you can walk on the tray to bed in and again, check levels several times

    The trays have a built in fall to get the water down the plug so keep tray nice and level - good luck

    Would also add that if the tray is going against any wall, put plenty of silicon between shower tray and wall/s to act as a seal should there ever be a leak between tiles and tray. Also helps to keep the tray free from any movement
    Last edited: Aug 12, 2017
  4. Doall

    Doall Active Member

    Me to

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