Stone Resin Shower Tray subfloor

[Brownstone1892]

I was torn between here and the tiling forum, but here seems more relevant.

I'm about to install a 1650x800 stone resin shower base and am wondering what i should put underneath it. I currently have new floorboards, but am happy to remove them if required. There is substantial crawl space uner the floor, so the waste is no issue. I will be laying 6mm NoMorePly cement board on the rest of the floor, as it will be tiled. I plan on using gripfill or similar for shower base adhesion.

Should I:

Install the try directly on the floorboards?
Install the tray on NMP Cement Board?
Install the tray on another material?
Install the tray directly on the joists?

Any advice would be greatly appreciated.

Cheers,

Carl...

 

[denso13]

Install the try directly on the floorboards?

That'll be fine, especially with new boards.

 

[Mr Chibs]

Mine is similar size, and set on a mortar bed, which is on plywood on top of floorboards.

Akward lowering the tray down if surrounded by three sides. I used ratchet straps as strops, to lower down, then pulled them out once it was flat.
Feels good when you are using it, very solid.

 

[Madrab]

Big heavy tray, I would recommend that supports (noggins/dwangs) are added in between the joist so the tray is framed all the way around it's outside edge to minimise floorboard deflection, especially if the nearest long edge seems to be sitting in the middle of a board and not on a joist, can't see the other long edge.

Are they wooden boards, 22mm? Are you thinking about tanking, especially as it's plasterboard walls? I presume the waste is being routed below the floor at its current level?

 

[Brownstone1892]

Big heavy tray, I would recommend that supports (noggins/dwangs) are added in between the joist so the tray is framed all the way around it's outside edge to minimise floorboard deflection, especially if the nearest long edge seems to be sitting in the middle of a board and not on a joist, can't see the other long edge.

Are they wooden boards, 22mm? Are you thinking about tanking, especially as it's plasterboard walls? I presume the waste is being routed below the floor at its current level?

Ah, just saw this message. In answer to your questions, they're 22mm boards. Tanking has been done. They're cement boards. And yes, the waste is being routed below the floor, as there's loads of crawl space underneath, which is accessible from under the house. The base is now in place, straight on the floorboards, with gripfill keeping it in position. The base doesn't require the support of sand/cement, as it is a modern base with support built in, it just needs fixing in place to avoid any lateral movement.

The blue thing you see around the base is a Classi Seal Flexible Waterproof Upstand, as seen here.

Now, time for the gallery (imagine the music in your head)

The red things are the supporting walls under the house, the blue things the joists, so I reckon it's supported well enough. What says you?