Typically, structures built for commercial use must conform to the International Building Code (IBC). Residential structures (single family homes, duplexes and townhomes) must conform to a similar, but separate set of standards, the International Residential Code (IRC). Prior to the 2009 I-codes, using a residential structure as business such as the hair salon pictured was a grey area subject to the judgment of local building officials.
Section 419 of the 2009 IBC allows for the mixing of residential and non-residential uses for one and two family dwellings (and townhouses) built under the IRC.
The limiting factors of a residential structure’s ability to be classified as a live/work unit are as follows:
1. The live/work unit is permitted to be a maximum of 3,000 square feet.
2. The nonresidential area is permitted to be a maximum 50 percent of the area of each live/work unit.
3. The nonresidential area function shall be limited to the first or main floor only of the live/work unit
4. A maximum of five nonresidential workers or employees are allowed to occupy the nonresidential area at any one time.
If the unit meets the requirements of Section 419 the residential use and non-residential use portions of the unit do not need to meet the separation requirements of Section 420 and 508. The non-residential portion may not be used purely for storage. The intent here is to not allow folks to rent their living rooms as a storage locker. Storage related to the non-residential function of the unit is permitted provided that it is 10% or less of the non-residential space.