Hello,The unexpected cost is due to flood and drainage issues with the property.

The house is almost 1300 sqft and i wanted to completely change 3 bathrooms, repaint the whole house(2 levels), change light fixtures and outlets, change doors only, remove carpets and redo the floor, completely redo the kitchen, and paint the exterior. the house seems to be in a pretty good shape but i am yet to see how many years the roof has left.

You don't want to spend your last dime to purchase the place because there's almost certainly going to be unexpected costs your first year of ownership.

From an initial standpoint, it seems to me that one of the benefits of the Design-Build firm would be a reduction in project management logistics & coordination, which would hopefully also lead to somewhat of a reduction in the unexpected costs that seem to occur due to miscommunication while coordinating various separate contractors.

We did just cosmetic changes like changing the outlets, light switches, and ceiling fans.

The GC should have accounts at various cabinet stores, wholesale granite yards, flooring outlets etc to get you a certain level of quality and might get a discount. 

It needs a repipe to replace polybutylene pipes, plus some minor electrical work (install GFIs, and correct a reversed hot & neutral wires in one outlet), and a new AC handler.

Hey @Ryan Van Duyne,The short-term rental business comes with many unexpected fees.

I was planning to put properly wired outlets near a window in each room, so that the tenants could buy and use their own ACs.Talking to a local landlord, he suggested I put in central AC.  

Upon looking through all the work done it was clear the house was fully re-wired since all the outlets were updated from an old school 2 prong to a grounded outlet and recessed lighting was installed.