Quote from @Jeremy Dugan: I am a US Air Force and Massachusetts Air National Guard veteran with 20-years of experience as a military Civil Engineer.

Work with your attorney for what is needed to insure all subcontractors get paid by the General Contractor.Make sure the insurance covers Construction period and also materials.Talk with your Commerical insurance agent and they should address the above questions with you.If this is an older facility make sure your engineering firm has covered Fire Suppression systems and any Storm pond or drainage systems. 

Whether that is most contractors, hiring an engineer, or getting self-educated.

Also, I'm a civil engineering expert in Building Information Modeling.

@Phil SheltonYou would need a civil engineer to provide a drawing to get submitted to zoning and get a permit if it passes zoning is most common This also depends on the road - if it’s a state road forget it as it will take a year to get approved and cost a fortune - if it’s a local road process not as cumbersome but don’t expect this to happen quicklyIn some instances you may have to prepare sight distances etc to make sure it’s safe to add a curb cut

@Michael Benanti Can you provide the apps proforma assumptions and algorithm?

These methods include: Detailed Engineering Cost ApproachDetailed Engineering Cost Estimate ApproachSurvey or Letter ApproachResidual Estimation ApproachSampling or Modeling ApproachExperience or “Rule of Thumb” ApproachIt’s important to understand the differences between the approaches including which one best fits your property and the reliability of each approach.DETAILED ENGINEERING COST APPROACHThis approach compiles the costs from construction and accounting reports to build a report.

By and large, QI's have very high ethical standards, and are sometimes overlooked as the engines of this tax saving tactic.]REPUTATION MARKERS 📊INDUSTRY STANDINGMembership in professional organizationsLeadership roles in FEAEducational contributions to the industryRelationships with major title companiesCLIENT RELATIONSHIPS 👥Testimonials from CPAs and attorneysReferences from title companiesLong-term client relationshipsTransparent fee structuresRELATIONSHIP RED FLAGS 🚩Overly familiar with your realtor/brokerKickback arrangements (illegal!)

It is very algorithmic-ly dictated based on and numbers and percentages. 

I'm a retired engineer and have been successfully using income from these houses to support my retirement without dipping into retirement savings.I'm transitioning my business from rentals to a franchise and would consider selling one of my houses (5 br/4 ba - the other houses my son while he's still attending).