I want to fit a new intermediate floor to an old stone house. It will be for a new bathroom (bath, shower etc) The space is 3.5M wide (joists this way) and 4.0M long. I plan to do this by fixing a wall plate (say 50 x 175) to the stone wall (random not cut stone) using ss studs (10mm) fixed into the stone with an injected chemical bonding agent. As far as I can calculate the total load on the floor should be less than 2,900Kg (14 sqM @ 2kN/sqM). Can I assume 1,400Kg on each wall plate and what loading should I allow for the ss studs in the stone wall (I though maybe 150kg should be OK thus needing 10 studs on each wall plate. Should I double the joists under the bath (assuming 50 x 170 @ 400mm centres and 3.5M long)?