Hi I'm currently doing my first bathroom and I've been trawling the internet for the answer (which is 42) to what subfloor to use in the bathroom. As a result, I'm lost and would really appreciate some direction. Joist centres are 34cm Joists are 8 X 2: complete span is be 2.6m max each beam. In the bathroom, there are no floorboards due to the previous owners tiling direct on to them so I just to meet the finished height outside the bathroom of 40mm. The shower tray is 25mm. The final floor will be amtico. Will the following work or is there a better way? Noggins at every unsupported edge. Option 1: Under the tray, 25mm marine ply between the joists. 18mm ply over the top. Tray on top. Finished shower tray height is 43mm Outside the shower area: 9mm ply strips on top of the 8 X 2 joists. 25mm ply on top. 6mm allowance for amtico and latex. Finished height is 40mm Option 2:. 22mm marine ply under the tray and shower area. Tray on top to make height 47mm. Outside the shower area:. Additional 12mm ply on top. 6mm allowance for amtico and latex. Finished height is 40mm Hope I've made sense and am least on the right track. Thanks Sent from my SM-G973F using Tapatalk