Here in the Pacific Nothwest I lay down 2 layers of the heaviest poly I can buy then tape all the seams with construction sheething tape. Interior slabs are insulated with XPS (extruded poly styrene).
Rebar is best when it is in the bottom half of (1 1/2" chairs) of the slab. This places the rebar in tension when the slab is loaded.
I use a 12"grid of 10M (3/8") rebar and sometimes fiber (interior slabs) to help to prevent cracking. Fibers that are sticking up afterwards need to be sanded or burned (propane torch) off.
10M rebar splices are overlapped 18" or more.
I'll manually tie with double loop ties or rent a cordless.
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When tying the rebar either use 2 wire ties that are 90 degrees to each other at each cross or alternate the angle from one to the next. Ties all at the same angle will pull the rebar out of square.
I'll bend the ends of the rebar at the perimiter of the slab past 90 degree with a 3"-4" tail but this
is not nessary.
Once the grid is tied take measuments of the rebar from a reference point. This helps when drilling holes in the slab at a later date.
If you layout the grid at exactly the desired spacing (line the ends up and use a square to mark each with a grease pencil.....don't use chalk it rubs off) then all you need is the measurement to the 1st bar.
Best to use large rock but if a pump is used the large rock will plug up smaller (cheaper) line pumps but not a larger boom (truck) pump.
Order extra concrete if a pump is used.
Don't overwork the finish and keep it covered or flooded with water.