Sewer smell

I've read alot on this forum, I just need to hear it from the experts. We had out home built last year, and our homebuilder subcontracted out the plumbing....to the lowest bidder. I won't elaborate on how unhappy I am with the plumber, we are currently in litigation with the builder because of all the mistakes.
We smell sewage emitting from the sinks, toilet etc. and "girggles" sometimes when flushing. I have very limited plumbing knowledge but I think our home has zero vents. Nothing on the roof either. Just a straight direct "tree" setup.
What are my options? Is it a major difficulty to retrofit vents and roof vents? Like I said our house is new so I want to correct this problem the right way and eliminate the nasty odors!

you have to draw it out. Post a diagram.

the good news is that you will know a lot more when it is all over.

david

With no sign of any vents, you may not be code-compliant. I would call the local health department and ask for a thorough inspection.