16 inches center to center, 14 1/2 between them.
This changes depending on your span. 2 x 8 normally.
The joist dimension can vary according to requirements, but typically solid wood joists are 9-1/4" in height (2x10).
it depen on the size of the joist
No gap is intentionaly left. Your squeaking will be between the subfloor and joists.
It depends on its moister content.
clearance between door and floor with forced air system
Stay as much towards the middle of the 2x10 as you can, but it is not going to weaken it that much.
If its wet I keep it tight, no space. With in weeks the wood will dry and shrink leaving the gap big enough.
It will require a minimum of three square feet of floor space.
Making an estimate on floor space of a three piece suite depends directly on how large the rooms are in the suites. The floor space can be anywhere from 1,000 feet to 20,000 feet or larger.
floor space has nothing to do with height. 81 x pi = 254.34 sq ft.
About 16 inches from the floor, that way it gives you about 5 inches to bend down into the box which is mounted at 12 inches.
You can do it with about 300 mm but you have to keep in mind what direction you are running the floor joists in. That way you will have to drill fewer holes in them.
How much slope and how long of a run? For short distance, up to 12 feet, and 12 inches of drop, you cut a 2x12 at the right slope and use them for the floor joist. For longer runs or greater slope, Use 2x6 level and use 2x4 legs under them.