For example for a roof you could need new decking or not, are they going to strip the roof or put a new 3rd layer? 

Two layers of carpet with one glued solid to the floor. 

Guessing you're desirous to turn your Pittsburg dirt into profits, I think you're on the right track though will suggest strongly that you yourself or someone very knowledgable that you can trust and manage babysits the process down to keys in hand, as I assure you, dealing with contractors and all entities along the developer's path takes an entirely whole new layer of skin and nerve.

A third party will force an additional layer of accountability and precision vs. one person doing it themselves.

I think you would have a difficult time finding someone to sell you a property, and the LLC layer adds some more difficulty.How soon do you turn 18? 

I would love to add a layer of protection and just curious about this approach.

We called this the "retro room" because of the 2 layers of awesome wall paper.

This stuff appears to have lifetime residential, 10 yr commercial, and wear layer 3 times as thick.

The rehab costs have far surpassed our budget due to some masked  issues(missing copper lines in walls, dangerous wiring almost throughout...all covered with sheetrock) Also, the city is requiring us to pour new approaches at "multifamily" thicknesses; about $9k worth. 

Can they just pour a new layer on top of the old layer?