New Mexico Administrative Code
Title 14 - HOUSING AND CONSTRUCTION
Chapter 7 - BUILDING CODES GENERAL
Part 4 - 2021 NEW MEXICO EARTHEN BUILDING MATERIALS CODE
Section 14.7.4.23 - COMPRESSED EARTH BLOCK CONSTRUCTION (CEB)

A. General. Compressed earth block shall not be used in any building more than two stories in height. The height of every wall of compressed earth block without lateral support shall be defined in Table 1 of Subsection B of 14.7.4.8 NMAC. The height of the wall is defined as the distance from the top of the slab or top of stem wall to the underside of the bond beam. Heights for exterior walls, which are laterally supported with those supports located no more than 24 feet apart, are defined in Table 1 of Subsection B of 14.7.4.8 NMAC. The bottom story of a two-story is allowed a minimum thickness of 14 inches with the upper story allowed a thickness of 10 inches, providing the structure meets the provisions of Table 1 of Subsection B of 14.7.4.8 NMAC. Passive solar structures incorporating the use of solar mass walls (trombe), direct gain arrays or sunspaces (greenhouses) as defined by the passive solar heating worksheet, dated June 2004 and prepared by the state of New Mexico energy, minerals and natural resources department, are allowed.

B. Fireplaces. Adobe or masonry fireplaces and chimneys in compressed earth block structures shall comply with 14.7.3.18 NMAC. They shall be integrated into adjacent compressed earth block walls during construction or secured to them by suitable steel ladder reinforcement or reinforcing rods.

C. Count Rumford fireplaces. Count Rumford fireplaces are allowed as designated in 14.7.3.18 NMAC.

D. Stop work. The building inspector shall have the authority to issue a "stop work" order if the provisions of this section are not complied with.

E. Stabilized compressed earth blocks. The term "stabilized" is defined to mean a block with certain admixtures that retains minimum strength requirements as specified in Subsection J of 14.7.4.23 NMAC after saturation in water. Saturation is defined as a minimum 4 hours of submersion in water as defined in ASTM D1633-00.

F. Unstabilized compressed earth blocks. Unstabilized blocks are defined as not meeting the minimum strength requirements as defined in Subsection J of 14.7.4.23 NMAC after saturation in water. Use of unstabilized compressed earth blocks is prohibited within four inches of the finished floor grade. Stabilized compressed earth blocks, poured concrete, or waterproof masonry units and mortar may be used for the first four inches above floor grade.

G. Materials. The material must be a mineral soil with the aggregate content not exceeding one inch in diameter. The material shall not contain more than two percent soluble salts.

H. Testing. Each of the tests prescribed in this section shall be applied to sample units selected at random of five units per building project prior to construction. Test may be waived if block manufacturer provides certification of compliance. The certification must be dated within one year of the date on the application for the building permit.

I. Shrinkage cracks. Shrinkage cracks are allowed, providing that these cracks do not jeopardize the structural integrity of the blocks.

J. Compressive strength. Cured units shall have a minimum compressive strength of 300 pounds per square inch when tested. The compressed earth block shall be tested in the flat position. The length of the test unit must be a minimum of twice the width. The surfaces must be smooth. The test unit shall be subjected to a uniform compressive load that is gradually increased at a rate of 500 psi/minute until failure occurs. A true platen should be used in the testing machine, along with swivel head to accommodate nonparallel bearing surfaces. The compressive strength is defined as P/A, where P = load and A - area of compression surface.

K. Modulus of rupture. Units shall have a minimum compressive strength of 50 pounds per square inch in modulus of rupture when tested according to the following procedures: A cured unit shall be laid over two-inch diameter cylindrical supports two inches from each end and extending across the full width of the unit. A cylinder two inches in diameter shall be laid midway between and parallel to the supports. Load shall be applied to the cylinder at a rate of 500 psi/minute until rupture occurs. The modulus of rupture is equal to: 3PL/2bt2 (P= rupture load in pounds, L= span between supports, b= width of block, t= thickness of block).