STATE BUILDING CODE INTERPRETATION NO. 01-08

CODE:

1997 Uniform Building Code (UBC) (as revised 2000)

SECTION:

310.6.1 Exception 3, and 313.6.1 Exception 3

QUESTION:

UBC Section 310.6.2, Floor Area, establishes 70 square feet as the minimum required floor area for a habitable room. In Sections 310.6.1 and 313.6.1, Ceiling Heights, Exception 3 states: "Not more than 50 percent of the required floor area of a room or space is permitted to have a sloped ceiling less than 7 feet in height, with no portion of the required floor area less than 5 feet in height." If it is the intent to limit to 35 square feet (50 percent of 70) the area allowed to be counted as habitable space with a sloped ceiling less than 7 feet in height, the state amended code language appears to make this section more restrictive.

Is it the intent of the Council to require a larger percentage of floor area to have a ceiling height of 7 feet or more than was previously required for habitable rooms larger than 70 square feet? 

ANSWER:

No. The purpose of the state amendment to the 1997 UBC Sections 310.6 and 313.6 was to reduce the required residential ceiling height from 7 feet 6 inches down to 7 feet.

Exception 3 is intended to convey that in a room with a sloped ceiling there must be a least 50 percent of the minimum required floor area (35 sf for 70 sf min.; 60 sf for 120 sf min. required by 310.6.2) with 7 feet or more clear height to the ceiling.

Any space in the room with a sloped ceiling beyond that minimum required floor area must be 5 feet or more in height to be considered "habitable space".

Space within that room under a sloped ceiling may be less than 5 feet in height, but cannot be counted in the habitable area of that room.

SUPERSEDES:

None

REQUESTED BY:

King County