Calculating Unit Costs

NOTE-- We retired the MacNail estimating program in 2000, and replaced it with Goldenseal estimating software. There are still die-hard MacNail users, so we keep the manuals online for them! Goldenseal is integrated software that also includes accounting, scheduling and contract writing features. Goldenseal uses Cost Items and Assemblies to calculate unit costs for construction work.

Figuring Unit Costs Directly

In many cases, you'll be able to figure unit prices directly, by calculating the number of actual person-hours it takes per unit, and the material cost per unit.

EXAMPLE: if it takes a crew of two carpenters 1 hour and 20 minutes to hang an exterior door, then the skilled labor cost will be about 2 * 1.33 hours, or 2.66 person-hours per door. If each door costs $235 and requires $55 of additional hardware, then the material unit price would be $290 per door.

If your crews fill out detailed time cards, then you'll be able to use their exact working hours to calculate unit prices for work that you've done in the past. This is the most accurate way to arrive at unit labor costs, since it's based on actual paid hours.

You can also try the stop-watch approach, or use an intuitive 'feel' for how long something should take. In such cases, it's a good idea to adjust the times upward by 10-25% to account for setup time, breaks, material deliveries, and other unproductive hours.

When calculating material costs in the MacNail construction management software, figure in a 'waste factor' to account for ordinary losses during construction. For even more accuracy, create material assemblies to calculate material unit prices (see page 118).