Fitting a shower tray on ply

Discussion in 'Plumbers' Talk' started by Neil Wolstenholme, Feb 12, 2019.

  1. Neil Wolstenholme

    Neil Wolstenholme New Member

    Hi All,

    I need some advice on how to fit a shower tray. I have a 760 x 760 mm, stone resin (ABS capped), low profile tray. It has been raised for access and drainage on wooden structure of 3x2 wood with 18mm ply overboard. The wooden structure is flat and secure, however my builder wants to just float the tray on top of the ply (not stuck to the ply with anything) but I think it needs to be bedded in on a 5:1 sand / cement mix.

    I have trawled through various forums and spoken to a few plumbers but no one can give a definitive answer.

    Any comments would be helpful as it is planned to be fitted tomorrow.
  2. Wayners

    Wayners Screwfix Select

    Wood gives a bit so a few blobs of silicone just to hold will do it... Never seen one cracked. They do rock though if you base is not strong so that needs to be firm..even on concrete some use wood dase to get it up for waste pipes
  3. CGN

    CGN Screwfix Select

    Silicone or a bagged flexible tile adhesive. Sand and cement is a waste of time imo.
  4. The Teach

    The Teach Screwfix Select

    for a start,the supplied tray will come with some instructions. If no instructions please contact the sales person who sold it to you they can supply pdf instructions.

    If no help from the sales people consider having it fitted professionally or purchase an alternative product which comes with diy instructions. Could offer more information if the tray manufacture is mentioned, hopefully its made for the Uk market.

    Most shower trays can be bonded (glued) on to any surface without a mortar mix, your builder needs to get a bathroom fitter involved o_O
  5. Neil Wolstenholme

    Neil Wolstenholme New Member

    Thanks for the replies all.

    Specifically for The teach:

    Thanks, let me clarify some more.

    This is the 3rd tray I have had fitted in the last 5 years. The first one leaked because of movement, the 2nd one leaked after a few months because of movement and then cracked recently. With this in mind I want to ensure this doesn't happen again. My house has a lot of vibration because of age / location, hence the belt and braces approach. The builder I have employed to fit it is a pro (general builder and bathroom fitter) who come recommended for a few people I know, so I have no issues with his work per se.

    The shower tray is manufactured by Iflo and bought at City Plumbing ( The technical datasheet just states bed in on sand / cement mix but is doesn't state the surface (ply or concrete floor). I have contacted the manufacturer and they are not sure with regards to ply. I have also contacted various branches of City Plumbing and they aren't sure either - some say silicon, some say sand / cement and some say flexible tile adhesive.

    I realise I am being a bit OCD about this but I want to get it right this time so I don't have the same issues again in a few months.
  6. terrymac

    terrymac Screwfix Select

    As you have had problems with movement in the past ,and one tray cracked , how were they fitted ? On the same timber and ply set up ,and what was used to bond them to the ply ?
    Flexible tiling adhesive will accommodate a degree of movement . However ,in your circumstances I wonder if a riser kit might be more suitable ,removing the natural movement of timber and ply out of the equation.( the specs for your tray above indicate its suitable for a riser kit )
  7. CGN

    CGN Screwfix Select

    Check your joists. Possibly some rot and loose in their pockets or even under specified. Installing a shower tray is not rocket science.
  8. Neil Wolstenholme

    Neil Wolstenholme New Member

    Hi Terrymac, The first one was on a older timber structure (not very robust) and was stuck down with silicon. The cracked one was on another timber structure ( like a horizontal stud wall) and again stuck with silicon. No ply overboard on either. I didn't want to use a riser kit because they never feel solid underfoot to me.
  9. Neil Wolstenholme

    Neil Wolstenholme New Member

    Thanks for the constructive comment. Joists have been checked and are fine. It seems there is a black art though as there is no standard way, silicon or tile adhesive or sand /cement or floating, hence my question!
  10. Neil Wolstenholme

    Neil Wolstenholme New Member

    Thanks all, I'm going with an SBR bond on the ply and then a 10mm 5:1 sand / cement mix and silicon seal around the wall edges of the tray. Fingers crossed.
  11. CGN

    CGN Screwfix Select

    No black art, just solidity of the main and sub structures involved. If on joists, then bounce up and down to gauge any possible deflection. If yes, sister joists and/or add extra noggins. Screw ply down and stick tray with tile adhesive after priming ply with sbr. I use a 12mm notch trowel to spread out adhesive. If building a riser, same attention to main floor, then use 3x2 or 4x2 on edge with ply on top.
  12. terrymac

    terrymac Screwfix Select

    As CGN said above ,worth checking below the flooring. A solid timber frame ,with 18 mm ply and flexible tile adhesive should be belt and braces as long as what it all sits on is solid. Tail end of last year I went to take out a tray / enclosure for a client and fit new. The old tray had been sat on expanding foam !! Had been leaking for quite some time ,and the joists below saturated to the point where I could push in a screwdriver to a depth of 3 1/2 inches. Young couple ,only bought the house 6 weeks earlier. Amazingly to me their insurers picked up the tab for new joists / flooring etc.
    CGN likes this.

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