Commercial GC Estimating: Direct Costs, Overhead, Profit, and Contract Types
Estimating is the most critical skill in commercial general contracting. An accurate estimate wins profitable work. An inaccurate estimate either loses bids to lower competitors or — worse — wins projects that lose money. This guide covers the full commercial GC estimating framework: how to structure direct costs, what overhead and profit markups are standard in commercial construction, which contract type fits which project scenario, and how to handle contingency and allowances without exposing yourself to scope creep.
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The Commercial GC Estimate Structure
A commercial construction estimate has four primary components:
1. Direct Costs: The actual cost of labor and materials to build the project. This includes your subcontractor bids, self-performed labor (if any), and direct material purchases. Direct costs should represent 70–85% of a typical commercial project's total cost.
2. General Conditions: The cost of running the project — project manager time, superintendent time, temporary facilities (site office trailer, portable toilets, fencing), project vehicle, permits and fees, testing and inspection, and insurance that is project-specific. General conditions typically run 8–15% of direct costs on a TI project and may be lower on larger ground-up projects with more efficiency.
3. Overhead: Your company's fixed costs that are not directly attributable to a specific project — office rent, administrative staff, software subscriptions, marketing, vehicles not on a specific project, professional services. Overhead allocation across projects typically runs 5–12% of project revenue depending on your volume. As you grow and spread overhead across more revenue, this percentage decreases.
4. Profit: Your intended markup above break-even. On commercial TI work, 5–10% profit margin is typical. Ground-up commercial work often sees 5–8% margins due to more competitive bidding. Healthcare and specialized work may command 8–15%. Your net profit (after overhead) is the number that actually matters.
Understanding Overhead vs. Profit
Many startup GCs confuse overhead and profit. They are separate and both must be explicitly included in every bid.
Overhead is what you spend to keep the lights on regardless of whether you win a project — your salary as owner/PM, your office, your software. If you have $300,000 in annual overhead and bid $5M in projects per year, you need to recover $300,000 / $5,000,000 = 6% overhead in every bid just to break even on overhead.
Profit is what you intend to earn above breaking even. A 5% profit on a $1M project is $50,000 — before owner distributions, taxes, or reinvestment in the business.
The total markup above direct costs and general conditions is your overhead plus profit — often expressed as O&P. A commercial GC with 10% overhead and 7% profit margin has an O&P of approximately 17–18% (not simply added — it compounds on the base). Use your estimating software or a construction accountant to model this correctly.
Lump Sum Contracts: Fixed Price, Full Scope Responsibility
A lump sum contract (also called a stipulated sum) means you are agreeing to complete a fully defined scope of work for a fixed price. If your costs come in under budget, you keep the difference. If they exceed budget, that is your loss.
When to use lump sum: When the scope is fully designed and documented (100% construction documents), when you have received competitive sub bids, and when you have a clear understanding of site conditions. Lump sum contracts shift the scope risk to you as the GC.
Risk management in lump sum contracts: Include a contingency line (5–10% of direct costs) in your internal estimate for unknown conditions, scope gaps, or sub performance issues. Do not include this contingency in your bid number — it is your internal buffer. AIA A101 is the standard owner-contractor agreement for lump sum commercial work.
Change orders are your revenue protection mechanism on lump sum projects. Scope creep — work that is added without a formal change order — is the primary way GCs lose money on lump sum contracts. Establish a firm change order process at the project kickoff meeting and enforce it consistently.
GMP Contracts: Open Book with a Ceiling
A Guaranteed Maximum Price (GMP) contract is a cost-plus arrangement where the GC agrees that total costs plus fee will not exceed a stated maximum. If costs come in below the GMP, the savings are typically shared between owner and GC per an agreed split (often 50/50 or 75/25 in favor of the owner).
GMP contracts are common on design-build projects, fast-track construction (where design is not complete at contract execution), and projects where the owner wants cost transparency. They require open-book accounting — the owner sees your actual cost invoices.
The fee in a GMP contract is your general conditions plus overhead plus profit, stated as a percentage of actual costs (typically 12–18% for commercial TI work). Your exposure is that if costs exceed the GMP, you absorb the overrun. Build a robust contingency into the GMP amount to protect yourself.
AIA A102 is the standard form for cost-plus with GMP commercial contracts.
Contingency and Allowances
Contingency: A dollar amount included in the contract to cover unforeseen conditions, scope gaps in the drawings, or minor design changes that do not rise to the level of a formal change order. Owner-controlled contingency stays with the owner; GC-controlled contingency belongs to you to manage project risks. On a TI project, 5–10% contingency is standard.
Allowances: When a design element is not yet specified at bid time (e.g., the owner has not selected flooring yet), the architect will include a unit price allowance (e.g., '$8/SF flooring allowance'). You include the allowance dollar amount in your bid. When the owner makes a selection, you reconcile actual costs against the allowance. If actual cost exceeds the allowance, a change order is issued. If it comes in under, the owner gets a credit.
Manage allowances carefully: Get allowance selections from the owner in writing as early as possible. Late decisions on high-allowance items are a major source of project delays and budget disputes.
Using RSMeans and Sub Bids Together
The best commercial GC estimates use two data sources in combination: RSMeans for independent cost validation and actual sub bids for the final number.
Process: Issue the bid package to your subs 10–14 days before bid due date. Use RSMeans to build an independent budget for each major scope. When sub bids come in, compare them to your RSMeans reference number. A sub bid that is 20–30% below your RSMeans number is either very competitive or missing scope — clarify before you include it. A sub bid that is 20–30% above RSMeans may indicate a capacity-constrained market where you need to shop for more sub bids.
Never build a final bid solely from RSMeans without actual sub quotes. RSMeans is a benchmark, not a substitute for competitive bids.
RECOMMENDED TOOLS
RSMeans by Gordian
The industry-standard construction cost database — localized unit costs for commercial construction across hundreds of assemblies and trades
AIA Contract Documents
Standard commercial construction contracts — A101 (lump sum), A102 (GMP/cost plus), and A201 (general conditions) used industry-wide
ProEst Estimating Software
Cloud-based commercial construction estimating with digital takeoff, bid management, and cost database integration
Some links above are affiliate links. We may earn a commission if you sign up — at no extra cost to you.
FREQUENTLY ASKED QUESTIONS
What profit margin should a commercial GC target?
Net profit (after overhead) of 5–10% is typical for commercial TI work in competitive markets. Specialized niches like healthcare construction or complex tenant improvements may command 8–15%. The key is understanding the difference between gross markup and net profit after overhead allocation.
How do I handle a project where my sub bids come in higher than my estimate?
You have three options: shop for additional sub bids to find lower pricing, reduce scope with the owner (via value engineering), or accept the higher cost and adjust your margin. Never submit a bid based on sub costs you are not confident in — a project bought at a loss cannot be un-bid.
What is an AIA G702/G703 and when do I use it?
AIA G702 (Application for Payment) and G703 (Continuation Sheet) are the standard forms for monthly contractor billing on commercial projects. G702 is the cover sheet showing total contract value, previous billings, and the current application amount. G703 breaks down the billing by line item (the Schedule of Values). Most commercial owners and lenders require these forms.
Should I include a contingency in my bid number?
Your internal estimate should always include a contingency buffer (5–10% of direct costs). Whether you expose this line item to the owner depends on the contract type. In a GMP contract, a contingency line is standard and visible. In a lump sum bid, your contingency is internal — you present a single total number and manage the contingency privately.