Skip to content
Menu

Labour and productivity

Sizing a crew for the work: when adding people slows it down

By Review.LivePublished 3 min readHow we write

The project manager wants the top floor of a head office boarded a day early and asks the drywall foreman for six hangers instead of the planned four. The floor has two open work areas and one panel lift. On the floor below, six hangers spent part of every day waiting for the lift.

An unoccupied timber apartment building under construction shows repeated wall bays and roof framing against a forested hillside.
Photo: Marek Ślusarczyk on Wikimedia Commons · Wood frame condominium construction in Canada – apartment building construction in Fernie, British Columbia · CC BY 3.0 · Cropped, resized, colour adjusted and sharpened.

Put on the smallest of three numbers: the people the quantity needs by the date, the people the open work areas and shared equipment can keep busy at once, and the people one foreman can keep supplied and checked. Beyond that number, extra people can add waiting instead of output. A survey of 54 mechanical and sheet metal projects in the United States found productivity losses of 0 to 41 per cent when a trade's peak crew rose above its average for the job, depending on how far the peak exceeded the average and how large it was. Those were whole projects in other trades: read the finding as a caution, not a forecast for your floor.

Three limits, then the smallest

  1. Start from the quantity and the date: work out the people the task needs at your crew's real rate, using durations from quantities.
  2. Count the places to work: rooms, wall runs or bays where a pair can work all day without waiting, and the lifts, scaffold bays, cutting stations and hoist time they share.
  3. Check the supervision: if the foreman spends the day finding tasks instead of checking work, the crew is bigger than one foreman can run.
  4. Take the smallest of the three. If the date needs more, change the plan rather than the crew: open another area, or give the extra people their own front and a lead hand.
  5. Watch the first two days: people waiting for a lift, two crews in one room, material in the walkways, output flat after people were added. Move people the day you see it.

Common mistakes

  • Sizing the crew from the finish date alone, without counting the places to work.
  • Judging a crew by how busy it looks, not by what it installs.
  • Stretching one foreman across two crews on two floors.

Checklist

Before you add people

  • The crew the quantity and date call for
  • Work areas and shared equipment, counted today
  • What one foreman can run
  • The smallest of the three
  • A front and a lead hand for anyone extra
  • Output per person, before and after

Check your understanding

The quantity calls for ten framers by the date, and the floor has five open fronts that each take a pair. Your foreman already spends much of the day finding tasks for six. What do you change before adding four?

Show the answer
Supervision is now the limit, not space. Give the extra people a lead hand and their own area with its own task list, or the four will wait for direction and slow the six. Then add them front by front and watch output per person.

Sources

  1. Impact of overmanning on mechanical and sheet metal labor productivity (Journal of Construction Engineering and Management, 2007): abstractArizona State University research portal · accessed

Related articles