Masonry Magazine September 1972 Page. 21
The distance between pilasters or between pilasters and endwalls or crosswalls should not be more than 18 feet for walls ten inches thick or 15 feet for walls eight inches thick. These distances should be reduced by three feet for grouted or mortared reinforcing bar wall stiffeners.
Horizontal stiffness can be increased by using horizontal steel reinforcement in the mortar joints at intervals of not more than 16 inches, or by bond beams.
Either sand and gravel or lightweight block may be used for foundations provided they meet specifications. Type M, S, or N mortar is suitable for laying the wall as indicated by Table 2, but Type N should not be used for walls extending more than five feet below grade.
Sill plates should be anchored to the wall at intervals of not more than six feet, and not more than 12 inches from the end, using one-half inch diameter bolts that extend at least fifteen inches into filled cells of the masonry units.
U-Factors
Thermal conductivities of foundation walls depend on the unit weights of the concrete in the block but typical values are given in Table.
Where girders bear on the foundation wall, at least two cores should be filled to a depth of six inches in the top course below the end of the girder. Pilasters are sometimes bonded to the wall at a girder location to provide additional support. The cores of the top course of pilasters should also be filled to a depth of six inches. In some basements it may be feasible if a center masonry bearing wall is used to eliminate the need for a center beam.
Ends of floor joists should be anchored at six-foot intervals, normally every fourth joist. At least the first three joists parallel to a wall should also be anchored to it at intervals of not more than eight feet.
Design for Watertightness
If each step in the construction of a basement is taken with adequate care there is no reason that the basement should not be completely dry. The common expectation that basements are damp or wet is unnecessary.
A bed of crushed stone should be laid inside the footing four to six inches thick over most of the area, but thicker at the edges. Drain tiles should be installed in the thicker perimeter area as shown in Figure 1. These drains should lead to a lower surface outlet or to a storm sewer. When the first course of block is being laid weep holes should be installed about every 32 inches to drain water into the crushed stone over the drain tile. The floor slab should be at least four inches thick and should be cast at a level above the weep holes.
The exterior of the walls should be plastered and coated with bituminous material. The surface must first be cleaned and dampened to provide a reservoir of curing water for the plaster. A 4-inch coat of portland cement-sand plaster is then troweled over the surface and allowed to cure and dry. Two brush coats of bituminous waterproofer are then applied. An alternative procedure is to use two 4-inch coats of plaster, and another method is to apply a heavy troweled-on coat of cold asphaltic mastic reinforced with fiber. No pinholes should be permitted.