Miami ADU/House-Hack Questions

[Shawn Bhatti]

Hi BP members,

To any that have experience with ADU construction/additions, preferably in Miami-Dade County:

My girlfriend and I are working on a new house-hack near the University of Miami. With a lot size of more than 8000 sq ft, we are considering building an ADU as an option to garner extra income each month. What are some metrics you aim for in terms of cash-on-cash return and overall ROI? 10%+ seems obvious for CoC return, but ROI seems more complicated. From what I have seen, adding an ADU may not yield a great value-add position, depending on the local market. Furthermore, appraisers may struggle to properly appraise the property as desired if nearby comps do not have ADUs/in-law quarters. Does anyone have insight into whether appraisers consider livable square footage for ADUs in conjunction with the main building, or is it separately calculated? Also seeking information regarding how new-build ADUs tend to align with the stringent Miami-Dade building code, in terms of structure type, impact windows etc. For a new build 2 bed/1 bath around 600 sq ft, we are probably looking at all-in costs around 120-180k. Thank you all in advance.