Shower tray support - could someone enlighten me please?

[lubemonkey]

Hi all,

I posted this in the plumbing section but no response as yet so I've reposted here (looking to buy my materials today...)

I'm replacing a small shower tray with a larger offset quadrant stone resin tray. The original tray was on a plinth built directly onto the joists because there are no floorboards under the tray, they look to have been rotted out and removed when this tray was fitted.

The new tray will have a riser kit.

I have a couple of questions:

1) I am going to put a piece of WBP 18mm ply down for extra support. As the boards are missing for the most part under the new larger tray, do I need to refit boards then put the ply on top? Or can I "embed" the ply into the floor?

I'll use extra bracing/noggins where needed. Embedding the ply would make it level with the boards and my riser panel should fit nicely. My concern with putting the ply on top of new floorboards is the riser panel will be hovering somehow.

I will be sanding and varnishing the original boards throughout the bathroom. They are 18mm.

2) How can a stone resin tray be ok supported by legs, when if bedded on mortar there is much said about trays failing if the tray isn't fully supported? Just a bit confused on that one. I just need someone to tell me the tray and riser kit will work fine really!

Any help much appreciated.

Lube

 

[^woody^]

You can just put the ply onto the joists, but even if you just place it on top of the existing boards, all you do then is adjust the legs down so that the plinth is against the floor with no gap

A tray designed for a riser kit will be OK, as it has specific reinforcing points for the legs

What I did with mine was support a 25mm ply board off some adjustable kitchen unit legs, and then bedded the tray on this board - so fully bedded, and room underneath to get to the trap. Best of both options

 

[lubemonkey]

Cheers Woody. Will probably re-instate the floor boards and put the ply on top as that will be easier than cutting/bracing the floorboards around the ply.

Like the ply/kitchen legs idea though!

- Lube