Resin shower tray .... Mortar or legs

28 Jan 2019
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United Kingdom
I'm replacing my old shower with a low profile resin tray. I've read up that I need to replace the (dodgy) chipboard floor with 18mm marine ply which isn't a problem, and want to lay it as low as possible so am putting the waste under the floor.

What I have read up is that the tray should be laid on a 10mm mortar base to ensure all the tray is supported so it doesn't crack. However, if I want to raise the tray I can use legs, and there seems to be typically 5 legs, one per corner and one i the middle.

So, how is 5 legs OK, but if laid on boards it needs 10mm mortar?

Supplementary question ... does the 10mm mortar raise the tray so there is a gap to seal, or is it all inside the tray edge?
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After a bit of reading I went with flexible tile adhesive for mine. Seemed like a popular choice and made sense to me. Very easy to get level and its been fine so far. Not following the manufacturer's instructions will likely void the warranty but I don't put much faith in them anyway.
Personally if I wanted to raise my shower tray, I'd construct a frame from solid timber (4x2") and lose the legs. There should be no area where the tray is not supported.
Resin trays need a nice solid and firm base, hence the requirement for a mortar bed. However if you are onto a good flat surface a heavy bead of silicone as a cushion is perfectly acceptable.
John :)
Thanks. I don't want to use legs, just wondered about support. How much mortar would I need for a 1400x900 tray?
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If its a more or less uniform 10mm bed a bucketful will do it. Mine was laid on concrete so it did lift the tray by about 10mm, mostly covered by the SLC I needed to correct my slightly listing concrete pad :). Enjoy lowering the tray flat onto the bed (good fun if you've only got access from 1 side)
I'm in the same position. I plan to frame it solid with treated 4 x 2. Obviously leaving access to trap but if enough of the tray had 4 x 2 support underneath I reckon it'll be fine.
Changing the subject slightly, I only had access from one side, I used ratchet straps to lower the tray down onto a mortar bed, then slide the straps out, might help one of you.
I laid a 1200 x 900 resin tray on a mortar mix, was really easy to do, just don't make the mix to firm or sloppy. It is to take out unevenness in the base of the tray, otherwise it will crack over time. I just laid the mortar and lowered the tray from one side. Checked the level and it was done.
I made a grid of 5mm silicone bead spaced 50mm apart and installed on that. 800x1200 tray. No issues 12 months on. Floor was checked as level before hand.

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