Setting Up Unit Costs

NOTE-- We retired the MacNail estimating program in 2000, and replaced it with Goldenseal construction estimating software. There are still a significant number of die-hard MacNail users, so we keep the manuals online for them! Goldenseal is an integrated program that also includes accounting, scheduling and contract writing. It uses a similar system of material unit costs, and construction assemblies.

Unit prices should be big enough. Ideally, you want the biggest possible assembly of work that doesn't have to be split into different options. Having separate items for wall studs and top/bottom plates would be unnecessary, for example, since they'd fit together just fine in a bigger item called 'wall framing'.

Unit prices should also be small enough. If the 'assembly' has too many components, you'll need too many line items to cover all possible permutations. For example, if you have a choice of two different kinds of exterior paint, five different siding types, three different exterior sheathings, four types of framing, six interior wall finishes and three types of interior paint or wallpaper, you'd need 2,880 different line items to cover all possible exterior wall assemblies. You could cover all of the same possibilities with just 23 lines by breaking each wall into six separate components.

When you use smaller 'chunks' of work in the MacNail construction estimating software, scheduling is also more accurate, and subcontracting to different sub-trades is easier. However, you may still want to create supplementary unit price items for larger assemblies that you do very often (see page 111).