An issue that emerged in the last year is a building official interpretation of the law and building codes that a two-unit townhome project is a duplex.  Your HBA disagree with that interpretation, which was supported by the International Codes Council.

A change to the 2021 International Residential Code, South Carolina’s Residential Building Code, allows a duplex to sit on two lots.  As a result of this change, Greenville County is no longer requiring two-unit townhomes to be combined and then subdivided after CO.  Instead, two-unit towns are permitted as a duplex on two lots.  A two-hour wall is required.

Townhome end units are popular, so two-unit townhome designs are becoming more popular.  Earlier this year, the Greenville County building official declared that a two-unit townhome project is a duplex. The building code states that a townhome is three or more units in a row. The zoning code also says that a duplex is two units on a single lot.

This interpretation, which has not been followed by other Upstate jurisdictions (yet), caused some builders to be required to combine lots, finish their projects, and then subdivide the lots after the certificate of occupancy is issued in order to sell the townhomes. In one case, a builder changed his plans to connect three two-unit townhomes with two roofs to get around the issue. The builder waited 18 weeks for building permits and has since had problems with the footing inspection because of this duplex interpretation.

The same official at the International Codes Council who backed up the county’s interpretation on two-unit townhomes was recently elected to the county’s Building Codes Board of Appeals by Greenville County Council,” Michael Dey, HBA vice president of government affairs, said.

“There has been debate nationally about this issue because of the fire separation requirement for townhomes vs. duplexes. A duplex only requires a one-hour wall. A townhome requires a two-hour wall,” Dey said. “This wall separation detail issue emphasizes the problem with this opinion, and why other building officials haven’t followed the county’s lead. By declaring two-unit townhomes a duplex, the county made it possible for a builder to build those units with a one-hour wall, at least until the end of the year,” Dey said. “I wouldn’t recommend that.”

As a result, in the 2021 International Residential Code, which takes effect on January 1, 2023, a duplex that has a lot line separating the two units requires a two-hour wall between the units. That change also makes clear that a duplex can sit on two lots, ending the issue of two-unit townhomes in Greenville County. “The county no longer requires townhome lots to be combined and subdivided after CO, but two-unit towns are now permitted as a duplex on two lots, and they will require a two-hour wall between the units,” Dey said.