Labor burden in construction: How to calculate it

Whatever you do, don’t be like Larry 

Today, the hero of our story will be Larry, the new CFO at T-Rex Roofing, a fictional commercial roofing contractor based in Dallas.

Ever since Larry joined 9 months ago, T-Rex Roofing has been on a tear. It’s winning new jobs at a breakneck pace and completing most of them with a healthy gross margin. The owners are thrilled: T-Rex is on track to becoming the leading roofer in Texas, leaving its competitors in the dust.

But Larry is puzzled. Despite the growth of the business, T-Rex Roofing’s operating income is flat, leaving the business with little capital to continue growing.

The root cause of Larry’s woes is simple: his estimates, bids, and job cost reports are based on unburdened labor costs instead of fully-burdened labor costs. This means that Larry is systematically underestimating T-Rex Roofing’s true labor costs, leading to bids that are too low and gross margin estimates that are too high. 

What Larry’s missing is the construction labor burden: the employer costs that stack on top of an hourly wage, from payroll taxes and workers’ comp to benefits. When labor burden isn’t built into job costing, every estimate runs short, every bid comes in too low, and profits get eaten before the job closes. This guide walks through what the labor burden is, what’s included, and how to calculate it so you can avoid job costing mistakes and bid with numbers that hold up.

What is labor burden in construction?

Labor burden refers to the indirect costs of employing a worker: payroll taxes, workers’ comp, health and life insurance, paid time off (PTO), and benefits. Fully-burdened labor costs are the total of direct costs (like wages) and indirect costs (the labor burden). 

Larry isn’t using the right numbers. If he calculated fully-burdened labor costs, he’d see what T-Rex spends on labor beyond base wages and the total costs for each job. With accurate numbers, his bids stop coming in too low, and project margins stop disappearing between the estimate and the closeout.

Realistic margin tracking requires contractors to calculate every dollar they spend on a project, including fully burdened labor costs. With a better understanding of which jobs are most profitable, Larry will know which to bid on and how many workers he can afford to hire for each project.

How to calculate labor burden: Unburdened vs. fully-burdened labor costs

Larry is committing one of the cardinal sins of job costing: he uses direct or unburdened labor costs instead of fully-burdened labor costs. 

Unburdened labor costs refer to an employee’s direct, gross pay. If an employee’s hourly rate is $25/hour, their unburdened hourly labor cost is $25/hour. 

Fully-burdened labor costs include direct costs (wages) and any indirect costs related to employment (labor burden). These are a mix of employer-paid expenses connected to labor, such as taxes, insurance, and benefits. 

Exact calculations depend on company policies and state requirements, but common categories include:

• Payroll taxes: This includes employers’ mandatory social security and Medicare (FICA) contributions, as well as federal and state unemployment taxes.
• Workers’ compensation insurance: These premiums can be significant, especially for higher-risk trades. Rates depend on individual job classification and company claims history.
• Employee benefits: Health insurance, retirement contributions, and life insurance add to the total cost of employing each worker. 
• PTO: This includes vacation days, federal holidays, and sometimes sick leave. These days add to labor costs because companies still pay employees for their time despite not receiving any output from them. 
• Training: Similar to PTO, mandatory safety training and specialized certifications require paid-for time away from work. The employer also usually has to pay for these sessions.
• PPE: Employers are legally required to provide physical safety gear, such as helmets and safety vests, for all relevant employees. The price of purchasing and maintaining this equipment needs to be factored into indirect costs.

Unburdened labor costs are useful for generating quick payroll reconciliations and raw labor spend analysis, but fully-burdened figures are essential for accurate job costing and margin analysis. According to Bureau of Labor Statistics benchmarks, relying on unburdened costs underestimates labor expenses by roughly 30%, leading to artificially competitive bids and cash flow deficits.

What is the formula for calculating fully-burdened labor?

To calculate fully-burdened labor costs, add up total indirect labor costs and total direct wages. Then, use this formula to find the labor burden rate:

Labor burden rate = Total indirect labor costs ÷ Total direct wages x 100

Once you have a burden rate for an employee or classification, you can use it for quick fully-burdened estimates. Multiply the base wage by the burden rate and add it back to get an approximate fully-burdened cost. That’s useful for fast bid math, but exact fully-burdened labor costs pulled from actual payroll data are always more accurate, especially on long-running jobs where comp rates, benefits enrollment, or PTO accruals shift mid-project. In construction, burden rates generally land between 25-40% of base wages. Rates well above that aren’t necessarily a problem – workers’ comp premiums on high-risk trades, mandated prevailing wage fringes, and union benefits all push burden up – but they’re worth a closer look to confirm the numbers line up with what you expect.

Example of calculating fully-burdened labor for an employee

Let’s see how Larry should calculate the costs for Mario, an installer at T-Rex Roofing. Mario’s base wage is $30 per hour. 

Instead of guessing at each indirect labor cost, Larry pulls payroll data from the previous quarter and converts those expenses into an hourly rate. For flat monthly fees like health insurance and annual expenses like safety training, Larry divides the total realized company cost by the total hours Mario was paid for to determine hourly contributions:

• Employer payroll taxes: $2.30 per hour (based on Social Security and Medicare at 7.65% of wages)
• Workers’ compensation: $2.55 per hour (premium rate for Mario’s classification comes out to 8.5%)
• Health insurance: $1.65 per hour (employer contribution averaged across total paid hours)
• Retirement contributions: $0.45 per hour (company match based on plan participation)
• PTO: $1.35 per hour (vacation and holidays spread across total hours worked)
• Training and PPE: $0.70 per hour (annual safety and equipment costs allocated per employee)

These calculations bring the total indirect labor burden costs to $9.00 per hour. Now, Larry can apply the formula for burden rates: 

$9.00 ÷ $30.00 = 0.30 (30%)

To find the fully-burdened labor rate (the dollar amount), he should add the base wage and the labor burden together: 

$30.00 + $9.00 = $39.00 

While Mario earns $30 per hour, the actual cost to the business is $39 per hour. That 30% difference is what Larry was missing in his estimates. Across a 1,000-hour job, that creates a $9,000 gap between estimated and actual labor costs.

Calculating labor burden for a whole workforce

Most contractors aren’t running these numbers employee by employee. Calculate burden rates by trade classification, like roofers, laborers, foremen, equipment operators, and apply those rates across all workers in each category for easier estimates. 

Note that most contractors update these rates quarterly or at the start of each fiscal year. Estimated burden rates don’t need to be perfect — they just need to be close enough to reflect reality. 

Be sure to keep classifications separate rather than blending them into a single company-wide rate: a roofing installer and a project foreman carry different workers’ comp rates, different overtime patterns, and sometimes different benefits packages, and averaging them together will skew bids. 

The challenge with doing this manually is that the inputs keep changing:

• Classification drift: Workers move between roles mid-job, and manual tracking rarely catches it until after the fact.
• Rate staleness: Quarterly updates means leaders are often bidding on last quarter’s numbers when benefits costs or comp premiums shift mid-year.
• Allocation errors: When a worker splits time across multiple jobs in a week, manually dividing burden costs across those jobs is tedious and frequently skipped.

Job costing software built for construction handles this automatically by connecting time tracking and payroll to attribute labor costs to the correct job and classification as payroll is processed. Burden figures reflect actual, realized numbers from each run, not quarterly or annual estimates that go stale between updates.

Common pitfalls to avoid when calculating fully-burdened labor rates

Even finance leaders who understand the basic concept of labor burden can make mistakes. Here are common errors to look out for:

• Omitting occasional costs: Forgetting to account for annual bonuses or sudden spikes in employer health insurance contributions can throw off calculations mid-year.
• Improper time-split allocation: Many employees split their time between multiple job sites. Failing to track their hours properly makes it impossible to allocate their labor burden to each project.
  Misallocating overhead labor: Project managers, estimators, and office staff aren’t direct labor, but you still need to track those costs. Misclassifying overhead employees as field labor, or leaving them out entirely, throws off both your burden rates and your job costs..
• Underestimating insurance costs: At renewal, general liability and workers’ comp premiums can shift significantly, especially after filing a claim. Using last year’s rates without checking current premiums builds a margin gap into your bids before the job even starts.

Improve labor cost visibility with Miter.

Labor burden math is only useful if the numbers going into it are accurate — and keeping those numbers current manually is exactly the kind of work that slips when jobs get busy. When workers’ comp premiums change, benefits costs shift, or a worker moves between classifications mid-job, estimates drift. Those changes need to flow into your burden rates. 

Miter connects time tracking, payroll, and benefits in one place so the inputs to your burden calculations always reflect what you’re actually paying.

Where Miter goes further is in the fully burdened cost data it produces. By syncing directly with your ERP, Miter generates actual fully burdened labor costs from real payroll data, rather than estimates you’ve built. 

And it doesn’t stop at the company level. Those costs are tied to specific jobs, phases, and classifications, so you can see exactly what labor actually cost on each project, and learn whether a job was profitable and how to price the next one.