Excerpt from “Advanced Code Requirements for Residential Construction
– Internet Course” by Becky Boucher

Slide 8: Minimum Room Dimensions:

The total area of a residence is generally not regulated by code; however a structure more than three stories in height would have to meet the provisions of the Florida Building Code- Building, rather than Residential Code. Only homes three stories or less, with a separate means of egress for accessory structures (like a garage or carport) fall under the provisions of the Residential Code. (FBC- Residential R101.2 Scope.) The Code does, however, have several minimum requirements that apply to residences. Residential space standards provide specifications for the internal floor area of dwellings and rooms.

Every dwelling must have at least one habitable room that has a minimum of 120 square feet of gross floor area. (FBC- Residential R304.1 Minimum area.) In most cases, this larger room is designed as the living area in a home. Other habitable rooms must have a floor area of at least 70 square feet (FBC- Residential R304.2 Other rooms.) and cannot have any one wall less than 7 feet in length. (FBC- Residential R304.3 Minimum dimensions.) The kitchen, however, though still considered a habitable room, can be a little smaller, but not less than 50 square feet in gross floor area. (FBC- Building 1208.3 Room area (Exception).)

A habitable room is defined as all rooms used for living, dining, sleeping and cooking purposes. Bathrooms, closets, halls, and utility spaces are not considered habitable rooms. (FBC-Building
202 Definitions.)

It’s important to keep in mind, that when figuring the square footage of a room, any portions of the room with a sloped ceiling measuring less than 5 feet or a furred ceiling measuring less than 7 feet from the finished floor to the finished ceiling are not included as habitable space for the room. (FBC- Residential R304.4 Height effect on room area.)

The home designer has the flexibility to distribute the total amount of space among the rooms as they wish, as long as the combined spaces and the individual rooms meet minimum code requirements.

Read full document here: http://www.floridabuilding.org/fbc/commission/FBC_0512/commission_education_poc/444/444-1-MATERIAL.pdf