(A) Compressive strength standard. Burnt adobe units shall have an average ultimate compressive strength of not less than 600 pounds per square inch. One unit out of five may have a compressive strength of not less than 500 pounds per square inch. Tests in accordance with ASTM C-67 for an approved testing agency shall be applied to five sample units selected at random for each 5,000 units used.
(B) Construction. All units shall be laid in running bond with full head and bed joints and a 50% lap. Walls shall be supported on foundation (stems) to maintain a minimum of six inches above adjacent ground at all points. Burnt adobe units shall not be used in any building more than one story in height. The unsupported height of every wall shall not be more than 15 times the thickness of such walls except that when gable construction is used, an additional four feet is permitted to the peak of the gable. Walls shall in no case be less than eight inches in thickness.
(C) Sealing. The surface of exposed walls shall be protected from water absorption by either exterior plastering or a chemical water-repellent sealer compound.
(D) Bond beams and anchorage. Bond beams shall be provided in support and anchor all roof construction. Bond beams shall have a minimum of three continuous rows of joint reinforcing between the required number of courses to resist uplift forces. Top plate anchor bolts shall be designed to resist the uplift forces (minimum one-half inch diameter and 20 inches embedment, 24-inch-on-center spacing) and provided with washers at least one-eighth inch thick by four inches by four inches welded to bolt. Top plate washer shall be a minimum two inches in diameter.
(E) Stresses. Burnt adobe masonry shall conform to the stresses set forth in Table 1.
Table 1 | |||||||
Type M | Type S | Type M or Type S Mortar | Type N | ||||
Material | Compression1 | Compression1 | Shear or Tension in Flexure2,3 | Tension in Flexure4 | Compression | Shear or Tension in Flexure | |
Unburned clay (adobe) masonry | 30 | 30 | 8 | 4 | | | |
Burnt adobe | 85 | 85 | 8 | | | 60 | |
1 Allowable axial or flexural compressive stresses in pounds per square feet in gross cross-sectional area (except at notes). The allowable working stresses in bearing directly on the concentrated loads may be 50% greater than these values. 2 This value of tension is based on tension across a bed joint, i.e., vertically in the normal masonry work. 3 No tension allowed in stack bond across heat joints. 4 The value shown here are for tension in masonry in the direction of running bond, i.e., horizontally between supports. 5 Mortar in masonry shall not be considered to resist axial tension. | |||||||
('80 Code, § 7-60) (Ord. 2021, passed 7-1-81) Penalty, see § 150-999