I am installing 3 floor drains in a shop building slab that is 2800 ft2. I was planning on running 2 inch abs and tying the drains together and then into an existing crawl space where septic line will be. In the crawl space I would put in a P-trap. I have heard that floor drains need to be 3 inch since they have no venting. Is this a good plan and is 2 inch or 3 inch the way to go?


J.Coyne