Example: Electrical costs with the labor cost column highlighted.

Supervision Expense to the general contractor is not included in the labor cost. The cost of supervision and non-productive labor varies widely from job to job. Calculate the cost of supervision and non-productive labor and add this to the estimate.

Manhours per Unit and the Craft performing the work are listed in the "Craft@Hrs" column. To find the units of work done per man in an 8-hour day, divide 8 by the manhours per unit. To find the units done by a crew in an 8-hour day, multiply the units per man per 8-hour day by the number of crew members.

Manhours Include all productive labor normally associated with installing the materials described. This will usually include tasks such as:

• Unloading and storing construction materials, tools and equipment on site.

• Moving tools and equipment from a storage area or truck on site at the beginning of the day.

• Returning tools and equipment to a storage area or truck on site at the end of the day.

• Normal time lost for work breaks.

• Planning and discussing the work to be performed.

• Normal handling, measuring, cutting and fitting.

• Keeping a record of the time spent and work done.

• Regular cleanup of construction debris.

• Infrequent correction or repairs required because of faulty installation.

Adjust the Labor Cost to the job you are figuring when your actual hourly labor cost is known or can be estimated. If the hourly wage rates listed are not accurate, divide your known or estimated cost per hour by the listed cost per hour. The result is your adjustment for any figure in the "Labor" column for that craft. Find out more. . . 

Adjust for Unusual Labor Productivity. Costs in the labor column are for normal conditions: experienced craftsmen working on reasonably well planned and managed new construction with fair to good productivity. Labor estimates assume that materials are standard grade, appropriate tools are on hand, work done by other crafts is adequate, layout and installation are relatively uncomplicated, and working conditions don't slow progress.

Working conditions at the job site have a major affect on labor cost. Estimating experience and careful analysis can help you predict the affect of most changes in working conditions. Obviously, no single adjustment will apply on all jobs. But the adjustments that follow should help you produce more accurate labor estimates. More than one condition may apply on a job.

• Add 10% to 15% when working temperatures are below 40 degrees or above 95 degrees.

• Add 15% to 25% for work on a ladder or a scaffold, in a crawl space, in a congested area or remote from the material storage point.

• Deduct 10% when the work is in a large open area with excellent access and good light.

• Add 1% for each 10 feet materials must be lifted above ground level.

• Add 5% to 50% for tradesmen with below average skills. Deduct 5% to 25% for highly motivated, highly skilled tradesmen.

• Deduct 10% to 20% when an identical task is repeated many times for several days at the same site.

• Add 30% to 50% on small jobs where fitting and matching of materials is required, adjacent surfaces have to be protected and the job site is occupied during construction.

• Add 25% to 50% for work done following a major flood, fire, earthquake, hurricane or tornado while skilled tradesmen are not readily available. Material costs may also be higher after a major disaster.

• Add 10% to 35% for demanding specs, rigid inspections, unreliable suppliers, a difficult owner or an inexperienced architect.