I'm putting in floor drains for mechanical room in barn, along with toilets, showers and sinks. The question is how far below bottom of concret (5" thick) should the traps be located.

Hi Grant:

The depth of your traps should be dependent on the pitch of your pipe... 1/4" per foot of pipe for 3" and smaller or 1/8" per foot for 4" and larger pipe. You want to determine the starting point of the main drain line and then calculate the distance and required pitch so that your farthest pipe ends up at least 3-6" below the concrete. The traps will automatically be in a good place with this standard.

Basically, the traps and piping cannot enter into the concrete and you want a minimum of a few inches of sand/pea gravel below and above the pipes.

Back to you...

Mark

I'm putting in floor drains for mechanical room in barn, along with toilets, showers and sinks. The question is how far below bottom of concret (5" thick) should the traps be located.
Mark gave you the skinny on traps,(your shower) under the floor however, since most floor drains have a built in trap, (see image)this shouldn't be a concern. Good luck, Tom

Where is your main trunkline going to tie onto? If you are tying onto an exsisting sewer line then you will need to know the depth of that line, or if you have a septic system , or sewer tap.