New shower, sewer small

[KJones2012]

Built a new $400,000 house last year. Basic one piece shower in master bath. Nothing fancy for plumbing fixtures. But shower drain stinks like sewer gas within 24 hours after a shower. Cleaned out the drain pipe with a paint roller and strong soap. Tried enzymatic drain cleaner. Tried vinegar and baking soda. The plumber was out and confirmed it has a P trap, it has standing water in it. Adjusted the drain assembly to make sure no pooling of water. I removed the flow restrictor from the shower head to make sure good flow of water. Plumber is stumped. I am stumped - but I am know little about plumbing other than to not touch it. It is not the tub, toilet, nor sinks - just the shower drain.

HELP - whatever could it be? Have you ever run across such a problem? What could possibly cause this? Would running a snake down there in case something weird got down there during construction? I am just totally stumped - and so is the plumber.

Sorry for the long email. All hints and/or solutions greatly appreciated! Thanks for your help. KJ

 

[havasu]

bump for an answer please

 

[plumb_bob_square_pants]

If the water trap is not all the way up to the weir then sewer gas will be let in. Not sure why that would happen unless they s trapped it. If they put a fitting right off of the trap at a 90° then the momentum of the water going through the trap would force all the water out.. does that make sense? Hope I'm explaining it clearly.