Labor Burden Calculation: What Belongs in Job Cost Beyond Wages

Why Base Wages Are Only Part of the Story

Most GC owners know their carpenters make $32 an hour. Fewer know what that carpenter actually costs the company per hour worked. The gap between those two numbers is labor burden, and if you are not calculating it correctly and charging it to jobs, your job cost reports are wrong. Period.

Understating labor burden is one of the most common reasons a job looks profitable midway through and then bleeds money at closeout. The fix is not complicated, but it requires discipline and a clear list of what belongs in the calculation.

What Labor Burden Actually Is

Labor burden is the total cost of putting an employee on a job, expressed as a percentage of base wages or as an additional dollar amount per hour. It covers every employer-paid cost that sits on top of the gross wage. When you charge a job for labor, you should be charging the burdened rate, not the base rate.

A carpenter earning $32 per hour does not cost you $32 per hour. After you add up everything below, that same carpenter costs $46 to $52 per hour depending on your benefits package and state. If you bill the job at $32, you are subsidizing every hour that carpenter works from your overhead and profit.

The Full List of Burden Components

Mandatory Payroll Taxes

These are non-negotiable and easy to quantify:

Workers' Compensation Insurance

This is often the largest single burden component for field labor. Workers' comp rates are set per $100 of payroll and vary dramatically by classification code. Carpentry work (NCCI code 5651) runs higher than supervision (5606). If you have multiple classifications on the same job, allocate the correct rate to each worker type rather than blending everything together. On a $75,000 annual wage, a 12% workers' comp rate adds $9,000 per year, or roughly $4.33 per hour based on 2,080 hours.

General Liability Insurance

Many contractors allocate GL premium to jobs as a burden component. Some carry it in overhead instead. Either approach works as long as you are consistent. If you allocate it to jobs, use the same per-$100-of-payroll method your insurer applies. Typical GC GL rates for field labor run 2% to 6% depending on scope and loss history.

Employee Benefits

This is where burden calculations get company-specific:

Union Fringes (if applicable)

Union contractors have it spelled out in the collective bargaining agreement. Fringe benefit packages covering pension, annuity, health and welfare, apprenticeship, and vacation funds are contractually fixed rates per hour. A union carpenter in Chicago might carry $18 to $22 per hour in fringes on top of the base wage. These are not optional, and they must hit the job cost record for every hour worked.

How to Express the Burden Rate

Once you have totaled every component, express burden as a percentage of gross wages. A typical open-shop commercial GC in the Southeast might look like this:

Applied to a $32 base wage, that is $12.78 in burden, bringing the true cost to $44.78 per hour. Round it to $45 for simplicity when building estimates and job budgets.

Recalculate this number at least once a year. Insurance renewals, benefit changes, and wage base adjustments all shift the rate.

How Burden Shows Up in Job Cost Reports

In CSI MasterFormat, field labor typically lives in the Division 01 through Division 09 cost codes depending on scope. When you post labor to a job, your accounting system should apply the burden rate and post the full burdened cost to the same cost code. Some systems post burden to a separate sub-code (e.g., 03-100-L for concrete labor and 03-100-LB for concrete labor burden). Others roll it up. Either method is fine as long as your job cost report reflects total labor cost, not just gross wages.

If your report shows $48,000 in Division 03 labor for a concrete package but only base wages hit that code, your cost-to-complete estimate for that scope is wrong by 35% to 45%. That error compounds as the job progresses and will show up as profit fade at the end.

The Practical Step Most Contractors Skip

Build your burden rate into your estimate at the line-item level, not as a lump-sum markup at the end. When you estimate 1,200 labor hours for framing at $38 per hour burdened, that $45,600 cost should match what your job cost system will accumulate as those hours are posted. If the estimate uses one rate and the job cost system posts another, variance reports become noise instead of signal.

Also, review your workers' comp and GL classifications annually with your broker. Misclassified employees inflate your burden artificially and expose you to audit findings at policy renewal.

Keeping Job Cost Accurate

Keeping job cost reports accurate takes constant attention. EZBilling ties every labor transaction to a job and cost code automatically, including the full burdened rate, so your reports reflect what the work actually costs.