For a century or more, productivity experts have been looking at factories and office buildings. In those environments, most of the variables are carefully controlled. If an assembly line is bottlenecking, you can create parallel lines at the crucial point, and move on. On construction sites, labor productivity is affected by more dynamic variables. This means you need to approach it from a larger framework, viz:
A great deal of downtime is caused by improper sequencing of subcontractors, or of discrete job elements. You can think of this as a human-resource corollary to zero-inventory management. But here it is “zero-waiting-around-for-the-other-guy-to-finish-something”.
Crowding is the most common breakdown of a good workflow. You cannot put too many people in the same space at the same time. When scheduling subcontractors, think about whether their work is going to impair—via dust, fumes, or foot traffic—adjoining work. Think about what time frame after they are done will be needed for things to dry, cure, cool down, etc. And then give all those margins a good margin for error.
Labor Fatigue and Scheduling
Human labor productivity starts to decline almost immediately once we go to work. Some studies show that the most productive workers are those who work relatively short days and take breaks up to 25% of the time. Needless to say, that is not the kind of worker that most of us are instinctively eager to hire. But think about this a different way: if you are working into the wee hours, you are paying people overtime for hours in which they are almost certainly less productive than the normal working day. You are paying more for less. How do you prevent that? By making realistic estimates of how long the job will take. If you have to rush, you should seriously consider hiring a second shift rather than the “zombie shift” of overtime workers.
The Missing Specialist
There are few labor markets so slow that you can’t find a guy to haul lumber. But scheduling your electrician or your plumber may be a little more tricky. And if you can’t get the electrician in until Wednesday, you may find that there’s not much to do on Monday and Tuesday. There will still be people on the payroll, though. The takeaway here is to schedule around your scarcest subcontractors and make sure they are reliable.