I am responsible for designing HVAC/plumbing systems for commercial buildings.

The plumbing scope found new plumbing in the house but outside the house was rusted cast-iron that the scope was unable to continue going through.

Had to fix a plumbing leak and replace subflooring in kitchen.

I hired a plumbing contractor and he installed a new furnace and copper piping. 

By the time it reaches the tax sale, the property has often been vacant for many years, with all the electrical, plumbing, and HVAC components having been stolen. 

But if you start changing plumbing or electrical then by all means get a good GC.

I keep comparing to Aussie and other countries world wide.Buyers agents pretty much don't exist and only listing agents do.true, US is almost always the most complicated one, in other country no need to have buyer agent but there're more, no need to pay tax when selling house, no need to put all 2000 pages disclosure when selling house  , no need to have house with so many certification (required in some states ) before renting it out , no need to hire expensive licensed american-born General contractor when repair house, no need to call specialized licensed educated electrician / plumbing with ipod because it's just .... plumbing. no need to pay tax with annual increase .... no need to pay ridicilous amount of insurance every year no need to check their credit score and immigration status when renter is impying LOL the list is on and on

Turns out I offered to do electrical and plumbing inspections on an agreed upon punch list. 

We also had to have the plumbing and electrical more or less 're-certified' by licensed electricians and plumbers - which some of which wasn't done to code either.

This little cabin was going to cost as much for the sub work (HVAC, plumbing, electric, etc) as our big cabin.Be thankful you got a new build when you did (we are!)