Masonry Magazine January 1977 Page.17
TABLE 2
Types of Mortar Permitted
| Kind of Masonry | Types of Mortar Permitted |
|---|---|
| Foundations: Footings Walls of solid units Walls of hollow units Hollow walls | M or S M, S or N M or S M or S |
| Masonry other than foundation masonry: Piers of solid masonry Piers of hollow units Walls of solid masonry Walls of solid masonry, other than parapet walls or rubble stone walls, not less than 12 inches thick nor more than 35 feet in height, supported laterally at intervals not exceeding 12 times the wall thickness. Walls of hollow units; load-bearing or exterior, and hollow walls 12 inches or more in thickness. Hollow walls, less than 12 inches in thickness where assumed design wind pressure: (a) exceeds 20 pounds per sq ft (b) does not exceed 20 pounds per sq ft Glass block masonry Non-bearing partitions of fire-proofing composed of structural clay tile or concrete masonry units. Gypsum partition tile or block Fire brick Linings of existing masonry, either above or below grade. Masonry other than above | M, S or N M or S M, S, N or O M, S, N, O or K M, S or N M or S M, S or N M, S or N M, S, N, O or gypsum Gypsum Refractory air setting mortar M or S M. S or N |
Based on Table 1. A41.1-1953(R 1970), "American Standard Building Code Requirements for Masonry."
*For design wind pressures, consult "American Standard Building Code Requirements for Minimum Design Loads in Buildings and Other Structures, A58.1."
Workmanship
In regard to workmanship, the A41.1 Standard (Section 4.2.1) contains the following general provisions:
4.2.1. Higher Stresses. Higher stresses than herein specified may be used, but only if it is clearly established to the satisfaction of the building official, by test, or other approved evidence, that material of a higher grade or a superior workmanship than is generally provided in accepted practice will be employed under approved inspection. The use of higher stresses, however, shall not be allowed until a statement giving the reasons for such permission together with the facts and circumstances on which it is based, has been placed on file and made a part of the official record of the permit.
Superior workmanship, as defined in the appendix of the A41.1 Standard, includes the complete filling of all joints and leveled (unfurrowed) bed joints.
The engineered masonry standards require a reduction in allowable stresses of one-third to one-half when the construction is not inspected by an architect or engineer to ensure, to the designer's satisfaction, that the workmanship is in accordance with the contract drawings and specifications. Therefore, the stresses given in Table 3 are considered to be those permitted "without inspection."
Composite Construction
As previously stated, an important aspect of the A41.1 Standard is that it provides for composite masonry constructions (e.g., brick and hollow concrete block; brick and structural clay tile) which are not covered by the engineered masonry design standards. The requirements of the standard are as follows:
4.2.2. Composite Walls. In composite walls or other structural members composed of different kinds or grades of units or mortars, the maximum stress shall not exceed the allowable stress for the weakest of the combinations of units and mortars of which the member is composed.