Plans & Drawings for Energy/Mechanical/Plumbing/Electrical

[Scot Fang]

Hello BP,

We built an addition to a SFH and converted it from a 1-residence to a 2-residence unit. The architectural plans and construction were approved and completed. Now the city is requesting the following:

1) Energy compliance documentation
2) Mechanical (HVAC) Drawings
3) Plumbing Drawings (Hot, cold water waste and vent. gas)
4) Electrical (Complete Drawings)

What kinds of people do we need to hire for these drawings and plans?  Is there a one-stop-shop kind of service for this?  Or do we need to find separate engineers / consultants for each item?  How do people usually go about finding these experts?  

After submitting the plans and getting approval from the city, are these tasks built by a contractor, or specialists such as electricians/plumbers/etc.?

Any referrals in the Socal area around the city of Diamond Bar would also be greatly appreciated.

Hopefully this is the last step needed before we rent out our property!

Thank you!