Masonry Magazine November 1963 Page. 6
The Contemporary Bearing Wall
Scaffolding can be much simpler in wall-bearing construction (Fig. 3) because the walls are built only to story height, and all masonry can be laid from scaffolds erected on the floor slabs. The height of a single frame of tubular scaffold is usually sufficient to top out the walls. All materials can be stocked and facing and backup laid up from this single scaffold.
FIG. 3 Multi-story Wall-Bearing Building Under Construction
It is desirable in wall-bearing design to obtain the maximum structural use from the masonry wall at the lowest possible cost. Most load-bearing walls, as presently built, utilize standard size clay facing brick backed up with hollow units. Oversize clay brick units are being produced and used in many areas to build walls with one material and can offer economies. Special load-bearing clay masonry units that can offer the advantages of a single unit through the wall are desirable. Such units eliminate the need for backup units and result in even greater construction economies.
For years it has been claimed that skeleton frame construction offers the most rapid and economical building enclosure. One of the claims of those promoting building panels, for example, is that their use permits much more rapid enclosure of the building frame, with resultant savings due to early occupancy. These claims, however, do not consider the length of time required to get the frame ready for setting the panels.
In a number of actual job situations, architects designing five to seven-story apartment buildings have cited both lower cost and earlier occupancy as their reasons for changing from skeleton frame to wall-bearing design.
The advantages of structural brickwork for wall-bearing buildings in heights of 15 or more stories have been utilized in Europe for a number of years. The renaissance of wall-bearing design in England, for example, has resulted in the design and construction of many wall-bearing structures of 12 or more stories, based upon the economies of this system over skeleton frame design.
1. CONSTRUCTION MATERIALS
# INTRODUCTION
In order to achieve the economies that are possible in wall-bearing construction, and to be certain that the walls will perform structurally in accordance with the engineering design, careful thought must be given to the type or types of masonry units and mortar used. Their specification, of course, will usually be the responsibility of the architect and his engineer. However, the mason contractor, with his knowledge of bricklaying costs and the effect on those costs that the type of masonry unit and mortar used can have, can be of valuable assistance to the designer and owner in the final selection of materials. No attempt will be made in this article to cover the engineering design of wall-bearing structures and the effect the choice of materials can have on the design. It should be emphasized however, that the unit compressive and tensile strengths that are required in the design and construction of multi-story wall-bearing structures of the types being considered can be found only in structural clay masonry units.
CLAY MASONRY UNITS
Wall-bearing clay masonry can utilize the standard sizes of brick and structural clay load-bearing tile that make up the major portion of the industry's production today. Since these units are available in all sections of the country, and most contractors are familiar with what is available in their own areas, no attempt will be made here to describe or discuss their use. Standard wall types using such units are well documented and described in the industry's literature (Refs. 1 and 2). A wide variety of wall types built with standard units are available for selection depending upon the requirements of the building. In many cases, the economy of wall-bearing construction compared to skeleton frame systems will not suffer by the use of conventional clay masonry walls built with what are considered to be "standard size" units.
However, it should be apparent that the larger the masonry unit, the less the cost of building the wall-up to a limit, of course. A unit that is too large and heavy for one man to handle easily may not be the most economical unit to lay. There are, however, larger size brick units produced in many areas of the country that do make possible more economical construction.
One size unit that does offer definite construction economies is the 4 by 4 by 12 in. brick that is now being used in many sections of the country (Fig. 4). A variety of wall types can be built utilizing this unit, from a simple two-unit 8-in. wall to a 12-in. masonry bonded hollow wall. Some manufacturers are also producing this unit in lengths up to 16 in.
4"x4"x12" BRICK
"SCR brick""
(6"x26"x12" or 6x4"x12")
"REG. U. S. PAT. OFFICE, SCPRF
NOTE: ALL DIMENSIONS SHOWN ARE NOMINAL
FIG. 4 Typical Large Structural Clay Lead-Bearing Units
In the types of multi-story wall-bearing structures being considered in this series of publications, solid masonry walls 6 or 8 in. in thickness will often be structurally adequate. Further economies can be achieved, therefore, if those walls are built with through-the-wall units, thus permitting both the facing and backing to be laid in one masonry operation.
For 6 in. walls, the "SCR brick" is an ideal unit (Fig. 4). This unit is normally produced with a norman brick face dimension (2-2/3 by 12 in. nominal dimensions), but is also available in some areas in heights up to a nominal 4 in. The 6-in. "Jumbo" or hollow brick (Fig. 5) produced by some manufacturers is another unit that can be used in the construction of 6-in. load-bearing walls.
"Reg. U.S. Pat. Off.. Structural Clay Products Research Foundation
MASONRY. November, 1