I also thought about potentially placing about 8 small storage units to give the tenants a place to rent for an extra fee for their extra stuff.Do "dog park" areas or private fenced in areas for tenants vs common open yard space see an increase in rents typically? 

What is everybody doing for on-site material storage?

ALSO" (i) Multiple accessory dwelling units within the portions of existing multifamily dwelling structures that are not used as livable space, including, but not limited to, storage rooms, boiler rooms, passageways, attics, basements, or garages, if each unit complies with state building standards for dwellings.

This house is on a full unfinished basement that I knew would be attractive to families who were moving to the area and needed ample storage.

I'm experiencing a similar challenge - looking to have an off-market deal appraised and so far, the two residential appraisers I've contacted have declined the job as "too complex" for them.The appraisal is necessary so that the seller and I can have a starting point for negotiation.The deal consists of (2) adjoined parcels: one parcel with a SFR, five car garage, trailer (will be removed prior to sale), and non-operational twenty unit storage building; the second parcel has a non-operational forty unit storage building.

You will also find Construction Management software built specifically for homebuilders and remodelers like BuilderTrend & Co-Construct.Podio, AirTable or SmartSheet could also be a good solution because they are very customizable, but will take some work to get up and running.Here's a summary of other products you might want to consider for project management below:General Business Task ManagementTrello/Zoho Projects/Basecamp/Workflow - Feature-rich project management software that includes Tasks, Gantt scheduling, calendars, project forums, document storage & team collaboration tools.  

I had an appraisal, the appraiser needed access to the storage units to get pics of the water heaters, and time was of the essence because I didn't want my locked rate to expire ( 30 day process I was on day 25).

Adding a storage shed might be needed for many who do this.

I am thinking of a storage unit here for the renters, but I'd like to know--for those investors that have built storage units before, what was the estimated cost? 

Now I'm involved with Self Storage and Manufactured Home Communities as well.