(A) Mortar. Portland cement mortar used in laying up masonry shall be mixed in proportion of one part of portland cement to not more than three parts of sand, by volume. Hydrated lime or lime putty may be added not to exceed 15% by volume of portland cement used. Cement-lime mortar shall be mixed in the proportion of one part of portland cement and one part of hydrated lime or lime putty to not more than six parts of sand by volume. Lime mortar shall be mixed in the proportions of one part of portland cement added to the amount of 15% of the volume of lime.
(B) Materials for concrete and cement mortar. Portland cement shall conform to the Standard Specifications and Tests for Portland Cement adopted by the American Society for Testing Materials under serial designation C9-26.
(1) Steel used as reinforcement for concrete shall conform to the specifications of the American Society for Testing Materials, as given in that organization’s standards.
(2) Fine and course aggregate and water shall conform to the specifications in the latest edition of the Building Regulations for Reinforced Concrete recommended and published by the American Concrete Institute.
(C) Bearing power of soils. In the absence of tests the different soils, excluding mud and quicksand, shall be assumed to sustain safely in following loads per square foot, and footings shall be provided under all walls and columns where required to keep the pressure on the soil within the limits specified in this section:
Soil Type | Loads per Square Foot |
Soft clay | 1 ton |
Firm clay, fine sand or layers of sand clay, wet condition | 2 tons |
Clay or fine sand, firm and dry | 3 tons |
Hard clay, course sand, gravel | 4 tons |
Soft rock, shale and hard pan | 8 to 15 tons |
Rock | 15 to 72 tons |
(D) Masonry walls. Masonry is that form of construction in which incombustible masonry units such as stone, brick, concrete block, or tile, hollow clay tile, gypsum block or other similar building units or materials or a combination of these materials, are laid up unit by unit and set in mortar. The minimum permissible thickness of walls and partitions of masonry, and the quality of these materials, shall conform to the recommendations in the report of the Building Code Committee of the United States Department of Commerce, and published under the title of Recommended Minimum Requirements for Masonry Wall Construction. Masonry bearing walls, party walls, fire walls, fire division walls, exterior panel walls, inclosure walls or curtain walls, eight inches or less in thickness must be laid in portland cement or cement lime-mortar as defined in this subchapter.
(E) Monolithic concrete walls. Monolithic concrete walls having less than 0.2% of reinforcing steel shall be considered as plain concrete walls and the thickness of single bearing walls of plain concrete shall be in accordance with the recommendations in the report of the Building Code Committee of the United States Department of Commerce as last published under the title of Recommended Minimum Requirements for Masonry Wall Construction. Subject to the other requirements of this subchapter, reinforced concrete bearing walls shall have a thickness of not less than six inches for the top story with the thickness of succeeding lower stories including basement, increasing at the rate of one inch for each two stories.
(1) In such walls the amount of reinforcement shall be at least 0.2% in each direction, horizontal and vertical, the steel being equally distributed on each face of the wall within a minimum bar spacing of 24 inches. The combined thickness of the separate parts of double or triple monolithic walls shall be not less than that required for single walls, and no single section of a double or triple wall shall be less than four inches thick.
(2) The sections shall be tied together with three-eighth inch round or square galvanized or tar-coated rods, with two-inch hooks at each end, the rods to be spaced not more than 18 inches horizontally and vertically. Exterior panel walls supported at each story of skeleton construction buildings shall be not less than five inches thick of reinforced concrete.
(Prior Code, § 7-2-7) Penalty, see § 10.99