The two walls were carried up simultaneously, one form being shifted into place and filled while the other was left in place until the concrete was sufficiently hard. It was found that 18 hours was amply sufficient to allow the concrete to set hard, after which the form was removed and lifted to a higher level. Thus the men were continuously engaged in lifting and filling first one form and then the other. The average length of time required to remove, raise and fill one form was 5 to 6 hours. Thus, two forms could be raised and filled almost every day. The construction of the forms and of the gallows frames is shown by Figs. 234 and 235. The cost of one set of forms and gallows frames was as follows:
| 320 ft. B. M. of 2×10 in.×10 ft. plank at $34 | $ 10.88 |
| 150 ft. B. M. of 3×4 in.×16 ft. spruce at $33 | 5.25 |
| 135½ ft. B. M. 1×8 in. yellow pine at $30 | 4.08 |
| 335 ft. B. M. 1¼×6 in. spruce at $33 | 11.05 |
| 4 posts 6×8 in.×26 ft. = 416 ft. B. M. at $30 | 12.48 |
| 4 sills 6×8 ins.×16 ft., 2 caps 6×6 ins.×9 ft., | |
| 4 braces 6×6 ins.×16 ft. = 490 ft. B. M. at $30. | 14.70 |
| 3 pieces 3×10 ins.×20 ft. = 150 ft. B. M. at $30 | 4.50 |
| ——— | |
| Total lumber (1,996.5 ft. B. M.) | $ 62.94 |
| Accessories: | |
| Bolts for trussing, 675 lbs. at 2 cts. | $ 13.50 |
| Iron guy rope and clips | 7.00 |
| Blocks | 8.00 |
| One coil of ¾-in. rope | 28.00 |
| ——— | |
| Total accessories | $ 56.50 |
| Labor making one outfit: | |
| 2 men, 8 days, at $2.75 per 9 hrs. | $ 44.00 |
| ——— | |
| Grand total | $163.44 |
This sum covered the cost of forms for one side of the building 85 ft. long and containing 150 cu. yds. of concrete, hence the cost of forms was in round figures $1.10 per cu. yd. of concrete. Each cubic yard of concrete required 1,997 ÷ 150 = 13⅓ ft. B. M. of form lumber.
The concrete was a 1-2½-4½ mixture. A careful record for 15 days, showed an average of 2.8 cu. yds. of concrete placed in 6 hours by a gang of 6.3 men. From this we can figure the cost of concrete in place to be about as follows:
| 2.8 cu. yds. concrete at $3 for materials | $ 8.40 |
| 6.3 men 6 hours at 15 cts. | 5.67 |
| 1 foreman 6 hours at $4 per day | 2.00 |
| ——— | |
| Total per cu. yd. | $16.07 |
Thus the cost of concrete in place was $16.07 ÷ 2.8 = $5.73 per cu. yd. Adding the cost of forms we get $5.73 + $1.10 = $6.83 per cu. yd. as the cost for labor and materials in constructing forms and mixing and placing concrete.
Fig. 236.—Detail of Column and Cantilever Column Footing for Four-Story Garage.
Offsets and molding decorations were easily made, although they were quite numerous on the building in question, at least more so than would ordinarily be the case in mill building construction. The offset of 1 ft. at every column was made very readily by sliding wooden shoulder pieces into place on the inner face of the form, which pieces in turn received 2-in. faced planking, the latter being slid into place from above. Thus the entire system was collapsible and small alterations were easily made whenever the form was shifted. Flat surfaces or offsets could be obtained at will by either removing or setting in the shoulder pieces. Molding effects were made on the front face of the wall by tacking molding strips to the form wherever necessary. The entire work was done with common labor and the finished building presented a smooth, homogeneous surface which required very little dressing.