The main guide lines focus on it being on a permanent foundation (Concrete slab), Hurricane tie-downs if you are in FL, GA, LA and a few other states, must be a double wide and not moved from another location.

The rental unit was probably built as an addition to our part it’s on a concrete slab, no crawl space. 

Or can you line it with concrete, and make it 30 feet deeper, with a smaller footprint, or put in several smaller ones?

There are a lot of opinions about which is better but nothing concrete.

I had a consultation with them last summer and feel like I need more professional help but just can't pull the trigger for the promise of what could be without concrete guarantees it will be worth it...

I can’t say that I’m familiar with the style of foundation that you have but from my experience, concrete cracks.

Furthermore, understanding the resident characteristics allows me to measure the target market and modify my investment strategy accordingly.Inspection ChecklistSituations vary from one property to the next, but here is an on-site inspection checklist to get you started:Interior Units:Inspect vacant units, including one of each finish out type (Classic, Reno, etc.).Check all down units.Inspect one unit from each unit mix.Exteriors:Landscape:Look for overgrown bushes.Identify trees that need trimming (no branches hanging over the roof).Take pictures of the following:Curb appeal on all sides facing the street.Landscape around the office and amenities.Overgrown bushes or trees.Any dead landscape.Areas that may need sod or mulch.Assess drainage:Ensure water flows away from building foundations.Check slope, gutters, downspouts, surface drains, French drains, etc.Exterior Walls:Determine the existing material (wood, vinyl, Hardie, brick, stone).Assess the condition of the walls.Note if painting is required.Take pictures of each building, including building number, each elevation (clockwise), and any breezeways or niches.Windows:Evaluate the condition of existing windows.Consider whether solar screens should be installed.Roof:Identify the type of roof.Assess its condition and age.Parking Lot:Check for potholes.Assess the need for restriping.Note whether the parking lot is concrete or asphalt.Evaluate drainage issues.Walkway:Look for tripping hazards.Assess drainage issues.Foundation/Gutters:Inspect for cracks in the brick.Check for separation in corners from fascia and trim boards.Evaluate drainage and identify poor drainage areas.Amenities:Identify possible improvements.Consider adjustments or additions that can enhance amenities.Talk to the Staff:Maintenance: Inquire about the physical condition.Office: Discuss current residents, delinquency, and potential changes to add value.Assess whether rents are too high or too low.Confirm rents and what is included/not included.Confirm other sources of income and associated charges.Confirm occupancy, pre-release, and vacancy numbers.Note: Maintain professionalism and avoid insulting the owner or broker, regardless of the property's condition.Keep in mind that investing in real estate is like solving a puzzle—you need all the pieces to see the big picture.

Pete a few months back I got really excited about BuildBlock Insulating Concrete Forms, or ICFs.  

When I was working in local government I once filled in a guy's yard with concrete that kept digging up our water line and stealing water.

Roof, windows, doors, furnace, hot water heater, concrete, etc.What research did you do on the neighborhood and probably tenant pool?