Hi there - I'm in a 30 year old truss built 4 level split home with 2x8 fir joist, 1x4 fir subfloor. Is it possible to do a natural stone floor - weighing about 3000 lbs 1" stone and 1/2 inch concrete mortar and subfloor? How would I calculate load? I've been advised that the rock ads about 6 lbs per sqft - way less than a fridge. Thanks Oh - in the living area I want to have a pool table 3.5x7 feet 1" slate.