ESTIMATED UNIT-COST Lh—Hourly Direct Labor. From his gen eral experience and what information he can gather from published data, the estimator is in a position to determine with fair accuracy between what limits he can reasonably expect to come on the item of direct labor, which is the funda mental labor charge and which ought to be nearly proportional to the actual amount of work accomplished.
L w and m—Weekly and Monthly Labor. This can be selected as a percentage of the item above mentioned, and depends very largely upon the local conditions, number of men employed, etc. Where there is a large amount of plant, such as steam shovels, hoists, drills, etc., it may run as high as 15 per cent maximum. For aver age work it is likely to be about of this.
should be allowed for loss in handling, shortage in shipment, etc.
It is a practice of many estimators to add from 5 per cent to 10 per cent to their estimate for miscellaneous and contin gencies. The more the detail of the estimate, the less the necessity for a large amount for this item. Miscellaneous items can cover possible inefficiency of laborers, strikes, raise in rates of wages, or unforeseen contingencies. From 5 per cent to 20 per cent of estimated labor cost is a fair allowance. It is an item used to insure against oversight or ignorance in making up an estimate. On materials the prices of which can be obtained before putting in a bid, there is no necessity for these.