How do I prepare marine ply base before fitting shower tray?

[old duffer]

Err really...plenty of boats built out of the stuff. - why would you have leakage and rotting ... its not a given unless the tray moves. Marine ply does not flex in comparison to either cement or tile backer boards and ties in the joists to a single unit increasing rigidity of the subfloor. As other have said seal the wall gap with a good waterproof sealant and add a shower band. Personally I have never liked sticking a tray down, good bed of sand and cement.

yes. and they made boats out of hollowed logs, rushes, animals skins...I'm sure that the titanic was made from cardboard...but it was waterproof cardboard...marine cardboard they called it

 

[Beverly27]

12mm is absolute minimum when over-boarding with ply, with your set up you need 22mm minimum .

Thanks foxhole, we used two sheets of 12mm, so 24mm in total. What's the reasoning behind the 12mm minimum?

 

[foxhole]

Thanks foxhole, we used two sheets of 12mm, so 24mm in total. What's the reasoning behind the 12mm minimum?

Thin ply flexes too easily .

 

[Diver Fred]

Thanks foxhole, we used two sheets of 12mm, so 24mm in total. What's the reasoning behind the 12mm minimum?

How was the 2 sheets bonded together?