The above rate is based on figures of 30c per hour. For other rates the following will apply in addition: At 35c per hour add 17%; at 40c add 34%; at 45c add 51%; and at 50c per hour add
Example:
(A) Take 1,000 feet of hardwood floor to be cleaned at 50c per hour =
$54.00 + $36.72 = $90.72
Looking again we find it would take 180 hours at 50c per hour = $90.00
(B) Take 1,000 feet of joists to be placed at 50c per hour = $6.00 +
14.08 = $10.08.
Looking for the hours we find it would take 20 at 50c, or $10.00.
83. Total Building Costs by Percentages.—Having carefully estimated the costs of one or two of the large items in a building, such as lumber or millwork or labor, the total cost of a building may be approximated with a fair degree of accuracy by a general contractor by means of the following table of percentages. Foundations or any other parts of a building which may be unusual should be excluded and figured separately in detail. In any event, before a building is finally completed the contractor will have to settle with each sub-contractor upon the basis of detailed cost estimates. Where time is available, the contractor as a rule secures bids from the various sub-contractors, such as the plumber, the lather, the mason, etc., combining these and adding his commission of 10% for oversight, and an additional 10% for incidentals or contingencies.
COSTS BY PERCENTAGES
| Items | Frame Building | Brick Dwelling |
| Excavation, brick and cut stone | 16% | 36% |
| Plastering and materials, including lathing | 8 | 6 |
| Millwork including glass and glazing | 21 | 20 |
| Lumber | 19 | 12 |
| Carpentry labor | 18 | 10 |
| Hardware | 3½ | 3 |
| Tinwork and galvanized iron | 2½ | 4½ |
| Plumbing and gas fitting and materials | 7 | 3 |
| Painting and materials | 5 | 5½ |
| Heating (not included) | ||
| Total | 100% | 100% |
Example:
A lumber bill for a given frame house is found to "figure" $500,
determine the approximate cost of the various sub-contracts, and
for the house as a whole.
Solution:
| $500 = 19% of the total cost. Total cost = $2632 (exclusive of heating). | |
| Excavation, brick and cement work = 16% of $2632 | = $421.12 |
| Plastering = 8% of $2632 | = 210.56 |
| Millwork and glazing = 21% of $2632 | = 552.72 |
| Carpentry labor = 18% of $2632 | = 473.76 |
| Hardware = 3½% of $2632 | = 92.12 |
| Tinwork = 2½% of $2632 | = 65.80 |
| Plumbing = 7% of $2632 | = 184.24 |
| Painting = 5% of $2632 | = 131.60 |
| Lumber | = 500.00 |
| $2631.92 |
To this must be added heating, electric wiring, electric and gas fixtures, window shades, cement walks, sewerage, grading, decoration of walls, architect's fee and contractor's commission.
For furnace heat, add 6 to 7% ; for steam, add 8 to 10% ; for hot water, add 10 to 12% additional.