That depends upon the size of the joists & grade/species of wood
That depends on how well supported the floor is and that depends on how far apart the joists are placed. The closer they are, the more weight can be supported.
Try not to invite Aretha Franklin and Queen Latifah over for dinner and your floors should hold up just fine.
Typically you would not put hardwood flooring directly over the joists. You should first put down a subfloor.
it can't hold very much weight
all depends how the floor is constructed and the size of the joists, the span of the joists, thickness of floorboards. Is it a concrete floor. Is it a 'live' load like people of furniture or a 'dead' load like an unsupported wall. It the house an old building or of recent construction. A residential standard suggests 40lb per square foot. Needs confirmation though
It depends on how the deckis "engineered". Some could be built that are barely able to support their own weight. Others could be built strong enough to park your car on them. It depends on the type and dimension of wood used for the joists, the spacing between joists and the length of the span.
It will hold more weight than you can ever put into it !- My floor joists are 2x10 at 16 inch intervals, and I installed a 48 x 60 spa tub that holds about 20 cubic feet of water, that weighs around 1200 pounds. Include two average people in it and you have over 1,500 pounds ! - The floor holds just fine .
That depends on the sise and the type of timber the floor boards are made of, However standard practice with flooring is 450mm centers or 600mm centers if the boards are thicker to allow for the extra 150 millimeter's
Depends on the area above the ceiling joists. Is it a live load (living space) or dead load (just the joists with maybe an attic above)? Also, the length of the ceiling joists from the last bearing point is a factor. How much weight is bearing on the beam is the critical issue.
20 times its weight in liquid
112lbs
it can hold as much weight as it can handle