Due to item 1, adding an ADU can require years to start achieving any return (once the accumulated cash flow recovers the initial negative position).4) Adding an ADU is a slow process.

I was accumulating Condos and not town houses in San Diego.  

@Delroy WatsonI recommend connecting with @Jonathan Klemm to get an estimate.

It may not appear this way on the surface but you are going to come out ahead by focusing on purchasing fewer but quality assets rather than becoming a door accumulator.

I wanted to share some key insights from Rentometer’s analysis of over 5 million rental searches in 2024. The findings are particularly interesting for those focused on the Columbus, Ohio market, which topped the list...

Quote from @Mike Sfera: for a duplex, is the BP rent estimate for per unit of combined?

For instance instead of having to stay glued to new listings, find the ones that show potential, then estimate rent, then put them in your calculator, then look at comps for ARV, then finally calculate offer price etc. 

We would be paid an hourly rate and whatever we  spend/accumulate; the friend would get the cash rent until the differance is paid. 

bottom line - you can't use a square foot estimate... you need a bottoms up estimate as @Samuel Eddinger alluded to.  

On the surface, the deal seems appealing, but there's a catch: the asking price is $475,000, which is about 18% over the market value (based on comps and DealCheck estimates around $402,000).Details of the DealProperty: Duplex, 2,400 sq. ft., Purchase Price: $475,000 ($197.9/sq. ft.).Estimated Market Value: $402,000 ($168/sq. ft.).Financing Terms: 2% interest rate, with a 9-year balloon.Unit B Income: $2,049/month (Section 8 tenant through November 2025).Unit A Income Potential: Similar rent or higher; Section 8 cap for the area is $3,234/month.Monthly Loan Payment (P+I): $1,386.Cash Flow Breakdown (if both units are rented at $2,049/month):Gross Rent: $4,098/month.Vacancy (10%): $410/month.Operating Expenses (37.3%): $1,376/month.Net Cash Flow: $943/month.Key QuestionsWould you be comfortable paying an 18% premium for financing at 2%, especially in a market where current mortgage rates are closer to 7%?