Im a new investor looking to make my first investment purchase and take advantage of the house hacking method. Ive

And your subs like electrical, plumbing, and HVAC need to pull permits so they are normally linked to the building permit. 

The biggest renovations we did to a house was paint and flooring throughout, whole new kitchen, new electrical, water heater, plumbing, new bathroom, and rebuilt part of the porch, and moved a window, and we didn't reach 20K so that might be a little high.

Then, find a mentor that has done these in your area so they can either a) share their methods or b) point you in the right direction. check out a few other pages on the forums. this community is home to loads of wholesalers, and everyone is eager to help each other find their own path.Good Luck!

@Roland Nelet this is definitely a bit of a broad question because so many areas have tons of specifics- carpentry, plumbing, electrical, hvac, drywall, roofing,, etc.

Consistent with Section 66013, the connection may be subjectto a connection fee or capacity charge that shall be proportionate to the burden of the proposed accessorydwelling unit, based upon either its size or the number of its plumbing fixtures, upon the water or sewer system.This fee or charge shall not exceed the reasonable cost of providing this service."

My long term goals are to utilize the BRRRR method to build my portfolio out of state (Arizona is currently a bit too hot, pun intended), and eventually move into larger deals. 

More commonly the popular method for water is Rubs per occupant since people use water and not sqft.

That would defeat the whole BRRRR method. 

For electrical and plumbing, the walls would need to be opened.