Resource Loading and Cost Loading: Do You Need Them?

Resource loading and cost loading are two of the most often requested and least often maintained features of a construction schedule. Both can be genuinely useful. Both can also turn into a large amount of data entry that nobody looks at after the baseline is approved. This post explains what each one is, what you get from it, what it costs to keep up, and a simple way to decide whether your job needs it.

Definitions

Resource loading means assigning labor, equipment, or material quantities to activities. "Steel Erection, Level 3: 8 ironworkers for 10 days, 1 crawler crane." The schedule can then show how many of each resource you need, period by period, and whether you have more demand than supply.

Cost loading means assigning dollar values to activities. "Steel Erection, Level 3: $180,000." The schedule can then produce a cash flow curve, support schedule-based payment applications, and feed earned value analysis.

They are related but separate. You can cost-load without resource-loading (common), resource-load without cost-loading (less common), or do both. Some schedules derive cost from resources by giving each resource a rate.

What cost loading gets you

• A cash flow projection. Owners and lenders want to know how much money is going out the door each month. A cost-loaded schedule produces an S-curve tied to the actual plan rather than a straight-line guess.
• Schedule-based pay applications. Some contracts require that the schedule of values match the schedule activities, so that percent complete on each activity drives the pay request. This keeps billing and progress honest with each other.
• Earned value. With cost loading and a baseline, you can compute planned value, earned value, schedule variance, and the schedule performance index. Earned Value for Construction Schedulers covers the details.
• A sanity check on the plan. If the cost curve shows 40% of the contract value spent in one month, something about the schedule is probably wrong.

What resource loading gets you

• A labor histogram. How many electricians, ironworkers, or drywall hangers you need each week. Useful for subs planning manpower and for GCs checking whether the plan is staffable.
• Resource leveling. If you need 14 carpenters in a week and only 10 are available, a leveling routine can delay lower-priority activities within their float to bring demand under the limit.
• Equipment planning. Crane time, hoist time, and lift availability are often real constraints. Loading them makes conflicts visible.
• Better durations. If durations come from crew size and production rates, the resource assignment is the documentation of the assumption. See Estimating Activity Durations the Field Will Believe.

A worked example

Three activities on a steel-frame building, using a five-day workweek. Steel erection runs four weeks. Metal deck starts two weeks after steel (start-to-start with a 10-day lag) and runs two weeks. Spray fireproofing follows deck and runs two weeks.

Spread each activity's cost and crew evenly over its weeks:

Week               1        2        3        4        5        6
Steel        100,000  100,000  100,000  100,000        -        -
Deck               -        -   60,000   60,000        -        -
Fireproof          -        -        -        -   30,000   30,000
Weekly       100,000  100,000  160,000  160,000   30,000   30,000
Cumulative   100,000  200,000  360,000  520,000  550,000  580,000

Ironworkers        8        8       12       12        0        0
Applicators        0        0        0        0        3        3

Total cost checks: $400,000 + $120,000 + $60,000 = $580,000, which matches the final cumulative value.

Two things fall out of this immediately. The cash flow is front-loaded in weeks 3 and 4, which the owner's draw schedule needs to know about. And ironworker demand peaks at 12 in weeks 3 and 4. If the steel sub can only staff 10, you have a choice: delay deck (which may push fireproofing and everything after it), extend steel erection with a smaller crew, or bring in another crew. A schedule without resource loading would show none of this. You would find out on site in week 3.

What they cost to maintain

This is the part that gets underestimated.

Cost loading is moderate effort to set up and relatively low effort to maintain, as long as the schedule of values and the activities are mapped once and kept in sync. The work shows up when activities get split, added, or deleted: the cost has to move with them, and the total has to still match the contract value. Change orders add cost that needs a home.

Resource loading is more expensive. Every duration change raises the question of whether the crew changed. Every new activity needs a resource assignment. Actual resource usage, if tracked, needs to come from timesheets or daily reports. A resource-loaded schedule that is not maintained produces histograms that look precise and are wrong, which is worse than no histogram.

A common compromise is to resource-load only the constrained resources: one or two trades that are genuinely in short supply, cranes and hoists, and maybe the superintendent's own crews. Everything else stays unloaded.

Do you need them?

Some quick questions to decide.

Government and large institutional contracts often require cost loading in the specification. Section 01 32 16 is the usual place to look, and Reading a Schedule Spec: Section 01 32 16 covers what those requirements tend to look like.

Practical tips

• Match the schedule of values to the WBS, not activity by activity. Mapping 400 activities to 400 SOV lines is painful. Mapping cost to WBS nodes or groups of activities is often enough for pay apps and cash flow.
• Do not cost-load level-of-effort activities with large amounts. General conditions spread evenly over the job will flatten your curve and hide the real shape of the work.
• Avoid front-loading. Putting disproportionate value on early activities to improve cash flow is a known practice, and reviewers look for it. It also distorts earned value.
• Use the same units throughout. Hours, crew-days, or headcount. Pick one per resource and stay with it.
• Level with care. Automatic leveling can produce strange results if priorities are not set. Review what it moved, and do not level the baseline without telling anyone.

If you do decide to load, schedule.construction supports resource loading and leveling and earned value from a cost-loaded baseline, so you can see the histogram and S-curve alongside the Gantt.

Key takeaways

• Cost loading gives you cash flow, schedule-based pay apps, and earned value. It is often contractually required.
• Resource loading gives you histograms and leveling, but costs real effort to maintain.
• Load only the resources that are actually constrained. Everything else is data entry.
• A loaded schedule that is not maintained is worse than an unloaded one, because it looks accurate.
• Check the spec first. If it requires loading, plan the mapping before you build the activities.