A co-worker of mine is selling her condo (which is not listed on the market) and is allowing me first dibs. 

I mean you technically require a permit to replace an outlet or sink faucet hahaha

I’ve worked for some group home providers where they employ a maintenance worker who handles some of these issues (usually if the have multiple homes in a specific geographic location) and I’ve worked for homes where the handiest employee fixes things and that option doesn’t always have the best outcomes.

If you did a full repipe and gutted the entire property then I assume (in all that means) that there were permits pulled and this should have been caught when the inspector did their rough in walk through or atleast the final occupancy inspection. 

This influx of workers will naturally drive demand for housing, retail, and other services in the surrounding areas, especially in smaller towns and cities that haven't seen major growth in decades.

I would mention to Tenant B that I was visiting Tenant A and smelled what seemed like marijuana smoke coming from their side and remind them there is no smoking permitted inside the house.

The foundation was already approved, permitted and finaled years ago for a 3400 sf house, and its solid and I won't be building directly on the overhang edge; but rather back away from the edge a few feet to prevent any load issues all the weight will be on the longer sides of the existing footing.

In my area a B class rental might be occupied by family with 2 wage earners each working full-time entry level jobs like warehouse workers.

The job starts when paperwork begins , ordering materials obtaining permits , lining up subs etc .

Supplement this far simpler entity approach by ensuring you have appropriate types and levels of insurance, you operate your business in a manner in which your conduct is not considered an exclusion in your policy, you work with licensed and insured vendors, you execute contracts with indemnification clauses with these same vendors/ require additional insured status &  maintain appropriate licensing and permits.