Home Design & Decorating Small Spaces Apartments

What Is a Granny Flat?

Pink front door of beach cottage

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Designed for one or two persons, a granny flat is a self-contained living area usually located on the grounds of a single-family home. A granny flat can be detached, or it can be attached to the other dwelling. Commonly called a granny flat because families can accommodate aging parents, it is more appropriately called an accessory dwelling unit.

What Is an Accessory Dwelling Unit?

A granny flat is formally called an accessory apartment or dwelling unit (ADU) in the building industry. Other colloquial terms include granny pod, mother-in-law unit, in-law apartment, bonus unit, casita, carriage unit, and ohana unit (primarily in Hawaii).

Many granny flats fall into the tiny house category, and the surge in interest in tiny house living has been a boon to older parents interested in this type of housing.

Granny flats or tiny homes may be used for nannies or young adult members of the family. They are sometimes used as rental units, but zoning laws and deed restrictions sometimes ban renting.

Multigenerational housing and granny flats are popular with realtors and builders because of their increased marketability, making them another good selling point for a property.

Fun Fact

The average tiny home measures 100 to 400 square feet, though it can be as small as 80 square feet or as big as 700 square feet.

Amenities in a Granny Flat

Some granny flats are miniature versions of full-sized housing units with complete kitchens. In others, kitchen facilities are limited, perhaps to a mini-fridge and microwave, which involve fewer safety issues than full kitchens.

The Granny Pod 

The newest wrinkle in the granny flat business is popularly called a granny pod. It offers high-tech monitoring capabilities so the inhabitant can be checked on via remote access. Other devices include a timed medication dispenser. The amenities that can be installed include a toilet that checks the temperature and does simple urinalysis.

Difficulty of Adding a Granny Flat

Barriers to the growth of granny flats include municipal statutes, zoning laws, building restrictions, neighborhood covenants, and other regulations. In many cases, homeowners ignore or circumvent such rules, which is relatively easy when converting a garage or other existing structure but less so when building a new one.

New construction is also more expensive, and homeowners may find it challenging to get financing. Connecting utilities can also be costly. Some municipalities require that driveways and off-street parking be provided for the granny flat occupant, which can add to expenses or be entirely unfeasible for specific properties.

The growth of the prefabricated or modular building industry has made it easier for some homeowners to add a granny flat, but this type of structure may be prohibited in some localities.

Advantages of Adding a Granny Flat

Besides providing living space, the granny flat offers other advantages. There is greater security with another tenant on the property, primarily if the apartment is oriented toward the side or back of the lot. Tenants can sometimes share transportation and other amenities with the occupants of the main house. Sometimes, they can share childcare, lawn care, and other maintenance tasks.