Yes, a shower needs a p-trap. If there is no p-trap installed then the sewer gasses have a clear path into your home. Any drain in your home needs a p-trap so there is standing water to block the gasses from floating through your drain and I to your house.
Improved answer
A trap does NOT have to be always "P" trap There are running traps J traps , LA traps depending on the application .. Showers and bath tub normally have a P trap main sewers and storm drains can have a running trapYes it does located in floor just below drain
Ans 2 - As difficult as it may be, if you don't have a trap under the floor drain you will get odours all the time.
Yes, somewhere in the line between the shower and the main.
A 50mm (2 inch) shower waste trap.
YES, it definitely does.
YES !!!!!!!! Minimum 2" P Trap Yes, and it needs a wye not a tee, and it needs to be vented properly.
Shower drain goes into a trap under shower. Continue piping from trap to drain line.
It may be sitting in the trap which should be located directly below the drain.
No and yes. Amendment (not from a professional plumber!): If you were simply running the sink drain into the shower drain and if there was not a reduction in pipe size, I would think you would be able to do that. I think the reason you need a trap for the sink has to do with code that requires a trap be no more than 24" from the basin to the trap arm. That being said, the pedestal sink in my house does not have a trap until after it drains below the floor.
It cant have more than 3 feet of length on it
Water won't drain from shower. Either trap or shower drain line is clogged.
2 in.
Its caused by dampness. The only solution to this is to strip your shower completely, tiles and old waterproofing (if any) and re-waterproof the shower and retile. I also recommend changing the shower trap and waste pipes along with the shower water pipes if one can afford to do so. Rather do the job once properly.
The building code is most likely going to require a trap to prevent gases from backing up into the house. I know they had to put them in my home.
Two inches