What a General Contractor Actually Does
A general contractor is not just a middleman who calls subcontractors. They are a project manager, a scheduler, a purchasing agent, a quality control inspector, and a risk manager simultaneously. The GC overhead and profit that shows up on bids — typically 15–25% of subcontractor costs — pays for all of this coordination plus the GC's license, insurance, bonding, and the liability they accept for the whole project.
When you act as your own GC, you take on all of those functions. If you have never managed a construction project, you are learning while spending hundreds of thousands of dollars. If you have done it before, you know exactly what you are signing up for.
Where You Actually Save Money
The real savings in owner-building come from eliminating the GC markup on subcontractor labor and materials. A general contractor bids out framing, HVAC, plumbing, and electrical, then charges you cost plus 15–25%. If you hire those trades directly, you pay cost only. On a $350,000 construction budget with 20% GC markup, that is $70,000 in potential savings.
You will not capture all of it. As an owner-builder, you lose the volume discounts GCs receive from material suppliers they work with regularly. You will also pay retail for materials that a busy GC buys at contractor pricing. Realistically, expect to net 10–15% savings on a well-managed owner-build, not the full 20–25% markup elimination.
The Hidden Costs of Owner-Building
Insurance is the first surprise. Builders risk insurance — which covers the structure during construction — is more expensive for owner-builders than for licensed GCs, and some carriers will not write it for owner-builds at all. Budget $3,000–$8,000 for a policy, and verify coverage before breaking ground.
Subcontractor management takes 20–30 hours per week during active construction. You are scheduling inspections, coordinating trade sequencing, resolving conflicts when the electrician's rough-in blocks a plumbing run, and chasing subs who are running behind. This is a full-time job during the build phase. If you have a full-time job yourself, owner-building will strain both.
Mistakes are expensive. A licensed GC who makes an error is liable for it. When you make a mistake — ordering the wrong windows, missing a plumbing inspection that requires a wall to be opened — you pay for it out of pocket with no recourse. The GC markup you saved can disappear quickly in a single significant error.
Who Should Consider Owner-Building
Owner-building makes the most sense if you have construction industry experience, a flexible schedule during the build, a strong network of trades, and a simple project — a rectangular single-story home is far more manageable than a complex custom two-story with multiple roof planes.
It also works well for people building in rural areas where GC availability is limited and trades are accustomed to working directly with owners. In dense suburban and urban markets, the best subcontractors have full books and prioritize GC clients who provide them with ongoing work over one-off owner-builds.
If you do pursue owner-building, hire a project manager consultant — someone with GC experience who advises you for an hourly or flat fee without taking the markup. This approach captures most of the savings while buying back much of the expertise.