22.10 - Plain concrete in structures assigned to seismic design category C, D, E or F.

concrete, except as follows:

(a) Isolated footings of plain concrete supporting pedestals or columns are permitted, provided the projection of the footing beyond the face of the supported member does not exceed the footing thickness. Exception: In detached one- and two-family dwelling three stories or less in height, the projection of the footing beyond the face of the supported member does not exceed the footing thickness.

(b) Plain concrete footing supporting walls are permitted, provided the footings have at least two continuous longitudinal reinforcing bars. Bars shall not be smaller than No. 4 and shall have a total area of not less than 0.002 times the gross cross-sectional area of the footing. A minimum of one bar shall be provided at the top and bottom of the footing. Continuity of reinforcement shall be provided at corners and intersections. Exception: In detached one- and two-family dwellings three stories or less in height and constructed with stud bearing walls, plain concrete footings with at least two continuous longitudinal reinforcing bars not smaller than No. 4 are permitted to have a total area of less than 0.002 times the gross cross-sectional area of the footing.

Ord. 2022-05 § 1, 2022

16.02.220 Amend Section 1907.1 General. Section 1907.1 General is deleted and based upon Express Findings 1 and 3 in Section 16.02.040 is amended to read as follows: 1907.1 General. The thickness of concrete floor slabs supported directly on the ground shall not be less than 3 1/2 inches (89 mm). A 6-mil (0.006 inch; 0.15 mm) polyethylene retarder with joints lapped not less than 6 inches (152 mm) shall be placed between the base course or subgrade and the concrete floor slab, or other approved equivalent methods or materials shall be used to retard vapor transmission through the floor slab. As a minimum and in all cases where a slab is to be placed inside of a building, the slab shall be reinforced with not less than six inches by six inches ten-gauge welded wire mesh or an approved alternate installed at mid height of the slab. Exception: A vapor retarder is not required:

(1) For detached structures accessory to occupancies in Group R-3, such as garages, utility buildings or other unheated facilities. (2) For unheated storage rooms having an area of less than 70 square feet (6.5 m2) and carports attached to occupancies in Group R-3.

(3) For buildings of other occupancies where migration of moisture through the slab from below will not be detrimental to the intended occupancy of the building.

(4) For driveways, walks, patios and other flatwork which will not be enclosed at a later date.

(5) Where approved based on local site conditions.

In all slabs under habitable spaces, a 4-inch (10 mm) crushed rock capillary water barrier shall be provided under the minimum 6 mil vapor retarder.

Ord. 2022-05 § 1, 2022