I've done 3 houses this year with the same contractors--all the houses were from the 30s or older, and needed all new electrical, all new plumbing, new roofs, new bathrooms, new kitchens.  

These are less regulated than a REIT structure (think: less expensive and more flexibility to set terms).  

Permitting it will entail removing the drywall and possibly insulation so the inspector can make sure the all the utilities (electrical, plumbing, hvac) are installed properly (per code).

Indoor plumbing? 

I will separate all electrical and plumbing, electrical will be individually metered and plumbing sub-metered.

It's not like screwing up a plumbing job and getting leaks. 

But, if you have to replace the roof, HVAC, upgrade electrical or plumbing, etc., that number may be low.

I act as GC on smaller rehabs and get licensed contractors for HVAC, electrical, and plumbing.

For instance, new HVAC, $5000,  replace plumbing $5000, fix, rewire or upgrade electrical $5000.  

I'll power wash the mold of the siding, put in some light bulbs, have the electric and gas and plumbing turned on (HUD winterizes houses) and get a Certificate of Occupancy inspection.