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  • Writer's pictureMaria Luisa Castellanos

Granny Flats – should we build them?

Updated: Mar 22, 2023

When I read this article in the Washington Post, The next big fight over housing could happen, literally, in your back yard , I was reminded of the controversy it generates here in Miami.

Many of you may or may not know that hundreds of thousands of properties have added illegal units to their properties here in Miami. The most popular one, of course, is the enclosing of the garage, adding a stove and refrigerator, and renting it out. The other one is taking one of the rooms in the house and converting it into another unit, sometimes with a kitchen or microwave, and sometimes it’s just a separate bedroom, most often with a bathroom. Much of this construction is done illegally. Most residential single-family zoning in the Greater Miami Area prohibits renting a second unit when the zoning is single-family residential, for example, RU-1 zoning in unincorporated Miami-Dade County. Although that is changing. For more information on converting your single-family house to a duplex, read my article and the county's new program on workforce housing here. There are those who argue that these illegal conversions depreciate residential neighborhoods. But if you drive through the streets of Miami, these extra units are everywhere. Recently, I was working on a school in West Miami and was surprised at the advertising in front of the school promoting their free lunch program. So I asked the principal with whom I was meeting how this could be. The neighborhood looked like a very nice middle class neighborhood. She said, “Do you see all those houses around here, they all have illegal units in addition to the primary houses. The people who live there all have children and they need the free school program.” So should these units be allowed? The Miami 21 Zoning Code for the City of Miami allows what it calls “Granny Flats” in certain areas. In T3-L zoned areas of town, granny flats are allowed. What was their reasoning? Miami is a city with a great Hispanic influence. It is very common to have 2 and/or 3 generations living in the same house. The granny flat provides an opportunity to have your elderly parents move next to you. This allows the younger couple with children to keep their eyes on the elderly couple. At the same time, this allows the older couple to babysit the grandchildren.

Another reason granny flats are allowed in the City of Miami is to have a mix of ages and incomes. Instead of homogeneous neighborhoods of one generation or one income level, the granny flat allows the owner of the main house to rent to a younger, less affluent couple or single person. This adds to the vibrancy of a neighborhood. In my opinion, they should be allowed everywhere. With rents rising and housing prices going up, the addition of independent buildings as shown in the diagram above in single-family residential areas would be a welcome relief to help cash-strapped Miami residents who, with each passing day, find it more difficult to find adequate housing. Should you wish to discuss the addition of a granny flat to your Miami single-family home, please feel free to call me at 305-552-5465 or email me at


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