Overhead costs are the expenses that keep your construction business running but don’t tie directly to any single job. Office rent, administrative salaries, vehicle costs, insurance, software subscriptions, and equipment used across multiple projects all fall into this bucket. To understand true job profitability, you need to spread these costs across your jobs in a consistent way.

The most common allocation methods for contractors are based on labor hours, labor dollars, or total direct costs.

Labor hours works well when your projects are labor-intensive and crews work consistent hours across different job types. Calculate your total annual overhead, divide by expected total labor hours, and you get an hourly overhead rate to apply to each job based on the hours worked.

Labor dollars makes sense when wage rates vary significantly across jobs or crews. A job using your highest-paid foreman should absorb more overhead than one staffed with entry-level workers. The math is similar: total overhead divided by total labor cost gives you a percentage to apply to each job’s labor expense.

Total direct costs (materials plus labor plus subcontractors) is the simplest method and works for general contractors who sub out most of the work. Apply the overhead percentage to each job’s direct costs. The downside is that material-heavy jobs absorb more overhead even if they don’t actually consume more of your indirect resources.

Here’s how to calculate it practically. Add up last year’s overhead costs. Identify your allocation base. Divide overhead by your allocation base to get your rate. For this year, apply that rate to each job based on actual hours or costs.

Example: If your overhead was $120,000 last year and your crews worked 8,000 total labor hours, your overhead rate is $15 per labor hour. A job requiring 400 labor hours should absorb $6,000 in overhead.

The method matters less than consistency. Pick one approach and stick with it so you can compare job performance over time. If you switch methods every year, your historical job data becomes unreliable for estimating future work. This is where proper job costing for contractors becomes essential because the structure has to support accurate allocation from the start.

Review your overhead rate quarterly or at minimum annually. If your overhead increased significantly due to a new office lease, additional vehicles, or hiring an office manager, but you’re still using last year’s rate, you’re underallocating. Your job margins look better than they actually are, which leads to underpricing future work.

Most contractors we work with in MetroWest struggle not with the math but with the discipline to track overhead separately and apply it consistently. Good business bookkeeping gives you the foundation to identify overhead costs clearly, separate them from direct job costs, and build allocation into your monthly reporting.

The goal is accurate job costing that feeds back into your estimates. When you know that similar jobs consistently run at 18% overhead, you can bid confidently. When overhead is a guess or an afterthought, your margins are fiction and you won’t know until year-end whether you actually made money.