Washington Administrative Code › Title 51 - Enterprise Services, Department of (Building Code Council) › Chapter 51-50 - State Building Code adoption and amendment of the 2021 edition of the International Building Code › Section 51-50-0602 - Section 602-Construction classification

Current through Register Vol. 24-14, July 15, 2024
602.4.2.2.2
Protected area.
Interior faces of mass timber elements, including
			 the inside face of exterior mass timber walls and mass timber roofs, shall be
			 protected in accordance with Section 602.4.2.2.1.
EXCEPTIONS:
Unprotected portions of mass timber ceilings and walls
						  complying with Section 602.4.2.2.4 and the following:
1. Unprotected portions of mass timber ceilings and
						  walls complying with one of the following:
1.1. Unprotected portions of mass timber ceilings,
						  including attached beams, shall be permitted and shall be limited to an area
						  less than or equal to 100 percent of the floor area in any dwelling unit or
						  fire area.
1.2. Unprotected portions of mass timber walls,
						  including attached columns, shall be permitted and shall be limited to an area
						  less than or equal to 40 percent of the floor area in any dwelling unit or fire
						  area.
1.3. Unprotected portions of both walls and ceilings
						  of mass timber, including attached columns and beams, in any dwelling unit or
						  fire area shall be permitted in accordance with Section 602.4.2.2.3.
2. Mass timber columns and beams that are not an
						  integral portion of walls or ceilings, respectively, shall be permitted to be
						  unpotected without restriction of either aggregate area or separation from one
						  another.
602.4.2.2.4
Separation distance between
			 unprotected mass timber elements.
In each dwelling unit or fire area,
			 unprotected portions of mass timber walls and ceilings shall be not less than
			 15 feet from unprotected portions of other walls measured horizontally along
			 the floor.
602.4.2.3
Floors.
The
			 floor assembly shall contain a noncombustible material not less than 1 inch in
			 thickness above the mass timber. Floor finishes in accordance with Section 804
			 shall be permitted on top of the noncombustible material. Except where
			 unprotected
mass timber
ceilings are permitted in Section
			 602.4.2.2.2, the underside of floor assemblies shall be protected in accordance
			 with Section 602.4.1.2.
602.4.4.3
Concealed spaces.
Concealed spaces shall not contain combustible
			 materials other than building elements and electrical, mechanical, fire
			 protection, or plumbing materials and equipment permitted in plenums in
			 accordance with Section 602 of the
International Mechanical
			 Code
. Concealed spaces shall comply with applicable provisions of
			 Section 718. Concealed spaces shall be protected in accordance with one or more
			 of the following:
1. The building shall be
			 sprinklered throughout in accordance with Section 903.3.1.1 and automatic
			 sprinklers shall also be provided in the concealed space.
2. The concealed space shall be completely
			 filled with noncombustible insulation.
3. Combustible surfaces within the concealed
			 space shall be fully sheathed with not less than 5/8-inch Type X gypsum board.
EXCEPTION:
Concealed spaces within interior walls and partitions
						  with a 1-hour or greater fire-resistance rating complying with Section
						  2304.11.2.2 shall not require additional protection.