Masonry Magazine September 1969 Page. 23
Estimating the Cost of Concrete Masonry
To estimate the cost of concrete masonry, the number of units required, and the quantity of other materials, cost of these items can be estimated from knowledge of local unit prices. Providing no errors have been introduced in estimating quantities, this is a reasonably accurate procedure. But, calculating labor requirements is less apt to be as accurate since labor requirements are subject to many factors. Here are some examples which will illustrate this point.
Building Type-A mason can lay more concrete masonry units per day on a factory or a warehouse having long straight walls than he can on a building having shorter walls interrupted by numerous doors and windows. A mason can also lay more units per day on a thick, multi-wythe wall than on a wall of lesser thickness. For different building types, the typical productivity values given in Table 4 should be altered 10 to 25%, plus or minus.
Weather-A mason can lay more concrete block on a warm, clear day than he can when it is cold or raining, or when it is necessary to heat masonry materials during freezing weather.
Workmanship-so called, "cheaper" construction may result in greater mason productivity, but its cost in the long run will seldom justify its use. Nevertheless, it must be recognized that crooked walls, open mortar joints, and walls that are slovenly in appearance require less effort to build than straight walls with full joints and plumb corners.
Your Local Producer
For additional assistance in estimating the quantity and probable cost of your concrete masonry needs, the sales department of your local NCМА member producer can be a most helpful source of information.
TABLE 2. CONCRETE MASONRY QUANTITIES
| | | | |
| :---------------------------- | :---- | :---------------------------- | :---------------------------- |
| Wall Gross Area | s.f. | | Deductions (special shapes) |
| Openings (deduct) | s.f. | | |
| Wall Net Area | s.f. | | |
| Corners (deduct) | | Unit | Number of Units |
| (No.) x (ht.) x (t) | | | |
| 12 | s.f. | | Full length |
| | | Corners | |
| | | Lintels | |
| Masonry Area | s.f. | Sash/Jamb | |
| | | Con.-Joint | |
| Total Number CMU's** | s.f. | Others | |
| | | Totals | |
| No. Number of corners. | | | Total Deduction in Full Length Units |
| ht. Wall height in feet. | | | Net Number of Stretcher Units |
| t. Wall thickness in inches. | | | |
| Based upon information contained in Tables 3 and 5. | | | |
TABLE 3. MORTAR AND CONCRETE MASONRY REQUIREMENTS FOR 100 SQUARE FEET OF WALL AREA
(Wall is assumed to be one masonry unit in thickness.)
| Nominal Height and Length of Units in Inches | Number of Units Per 100 Sq. Ft. | Cu. Ft. of Mortar Per 100 Sq. Ft. |
| :------------------------------------------- | :------------------------------ | :--------------------------------- |
| 8 x 16 | 112.5 | 6.0 |
| 8 x 12 | 150.0 | 7.0 |
| 5 x 12 | 221.0 | 8.5 |
| 4 x 16 | 225.0 | 9.5 |
| 24 x 8 | 675.0 | 14.0 |
| 4 x 8** | 450.0 | 12.0 |
| 5 x 8*** | 340.0 | 11.0 |
| 2 x 12**** | 600.0 | 15.0 |
| 2 x 16***** | 450.0 | 15.0 |
| Modular Concrete Brick (2% x 3% x 7%). | | |
| Jumbo Concrete Brick (3% x 3% x 7%). | | |
| Double Concrete Brick (4% x 3% x 7%). | | |
| Roman Concrete Brick: (1% × 3% x 11%) | | |
| (1% x 3% x 15%). | | |
TABLE 4. TYPICAL VALUES FOR NUMBER OF CONCRETE MASONRY UNITS LAID PER 8-HOUR DAY BY A SINGLE MASON
| Size of Masonry Unit, in. WxHxL | Number of Units Per 8-Hour Day |
| :-------------------------------- | :----------------------------- |
| 4 x 8 x 16 | 200 |
| 6 x 8 x 16 | 180 |
| 8 x 8 x 16 | 160 |
| 10 x 8 x 16 | 140 |
| 12 x 8 x 16 | 120 |
| Concrete Brick: | |
| Modular | 800-900 |
| Jumbo | 600-700 |
| Double | 400-500 |
| Roman | 250-350 |
| Decrease by 10 percent for normal-weight and heavy-weight units. | |
| Increase by 3-5 percent for 12-inch long units. | |
| Increase 15 percent for 4-inch high units. | |