When to Hire a Concrete Contractor vs. DIY
This isn't a skill question, and treating it as one is why people get it wrong. What actually changes from a patio to a driveway to a footing isn't how hard the work is — it's how many people have to be holding a screed at the same moment, whether the law lets you do the work at all, and what it costs to undo if it goes wrong. Three gates answer it. Fail any one and the project isn't a DIY project, no matter how capable you are.
Almost every article on this subject quietly uses a patio as the template, and that's a problem: the patio is the one project where every hard variable happens to be favorable at once. Its failure is cosmetic, it's cheap to break out and redo, and most jurisdictions don't regulate it. None of that generalizes to a driveway, a garage floor, or a footing — so the reasoning that makes a patio an easy yes doesn't carry over.
The three gates
Each gate is a yes-or-no question, and a no on any single one ends the discussion. They're not weighted and they don't average — passing two out of three isn't a pass.
| Gate | Question |
|---|---|
| 1. Structural | Does anything rest on it, lean against it, or depend on it staying where it is? |
| 2. Legal | Permits, pre-pour inspections, right-of-way rules, owner-builder exemptions, and what happens at resale. |
| 3. The clock | Can your crew place and screed the volume inside the working window before it sets? |
Gate 3 is the one almost nothing else written on this covers, and it's the only one you can compute exactly in advance — see below.
Gate 1: Is it structural?
The test is one question — does anything bear on it that would be damaged if it moved? Not "is it thick." Not "is it big." A 400 sq ft patio isn't structural. A 4 sq ft pier under a deck post is.
| Project | Bears what | Structural? |
|---|---|---|
| Patio, walkway | Foot traffic and furniture | No — movement is cosmetic |
| Shed pad | A light structure that can be re-leveled | Marginal, usually non-structural |
| Driveway | Vehicle loads, repeatedly, for decades | Not structural, but load-bearing and expensive to replace |
| Garage floor | Vehicles — and often the walls, if monolithic | Depends — see below, this is the trap |
| Steps | People, with code-governed dimensions | Yes, in the life-safety sense |
| Retaining wall | Soil pressure — enormous and constant | Yes — failure is sudden, not gradual |
| Footings, piers, stem walls | The entire structure above | Yes, unambiguously |
A floating slab poured inside an existing garage, independent of the walls, carries nothing but vehicles — non-structural. But many garage slabs are monolithic: the floor and a thickened perimeter footing are poured as one piece, and that turndown carries the walls. In that case the slab is the foundation. The same square of concrete is a floor or a foundation depending on a detail at the edge that's invisible once the walls are up. If you're pouring a new garage, assume monolithic. If you're replacing a floor inside a garage that already stands on its own footings, it's non-structural — but don't disturb those footings while breaking out the old slab. If you don't know which you have, that uncertainty is itself a fail on this gate; one call to your building department resolves it.
Two that get underestimated
Retaining walls look like stacked masonry and behave like a dam. Soil exerts lateral pressure that increases with depth, and saturated soil after rain exerts substantially more — the wall has to resist overturning, sliding, and bearing failure. Most jurisdictions require a permit above 3–4 feet and engineered drawings beyond that. Below the threshold, a dry-stacked landscape wall is a weekend project; above it, you're designing a structure that can fail catastrophically, sometimes years later, usually after a wet spring.
Steps carry the tightest tolerance in residential construction: codes govern riser height, tread depth, and — the one that catches people — the maximum variation between risers in a single flight, commonly 3/8 inch. People climb stairs by feel rather than by looking, so one riser that differs from its neighbors is a trip hazard an inspector will measure.
Gate 2: Does the law let you?
Most states let a property owner act as their own contractor on their own home without a license. That exemption is narrower than it sounds:
- Occupancy intent — you typically must intend to occupy the home; building for immediate resale can void the exemption.
- Frequency caps — Florida, for example, limits owner-builders to one exempt project per 24 months.
- Resale disclosure — California requires disclosing owner-builder work if the home sells within a year of completion.
- Lender requirements — construction loans often require a licensed contractor regardless of what the state exemption permits.
- It never exempts you from code — the work still has to comply and pass inspection.
The section of driveway between the street and your property line — the apron — sits in the public right-of-way, even though the driveway it connects to is on your land. For pavement cutting, excavation, or traffic control, most agencies require a licensed, right-of-way-registered contractor because of bonding and insurance requirements; a certificate of insurance, a bond covering pavement restoration, and a separate ROW registration are typical. You may be free to pour everything on your own property and legally barred from pouring the twelve feet nearest the street. That's not a skill gate — it's a credentials gate, and no amount of competence gets you through it.
For anything with a footing, inspections happen before the pour, not after — with the trench open, grade stakes set, reinforcement tied, and forms braced, and the concrete can't be placed until it passes. That creates a three-way scheduling collision between the inspector, the ready-mix supplier, and the weather, none of which coordinate with each other. A contractor does this every week; a homeowner does it once. Schedule the inspection first, pass it, and only then confirm delivery — the extra day costs nothing next to a cancellation fee on several yards of concrete while an open trench sits through a rainstorm.
Your homeowner's policy generally excludes your own faulty workmanship, and unpermitted work surfaces at resale — buyers' inspectors find it, and some lenders won't finance a house with unpermitted structural work. Every legal claim above is jurisdictional; treat it as a list of questions for your building department, not an answer for your address.
Gate 3: Can your crew beat the clock?
Concrete has a working window — roughly 60 to 90 minutes at moderate temperatures, less in heat, wind, or direct sun. The entire pour has to be placed and screeded inside it, because concrete placed against concrete that's begun to set doesn't bond into one piece. You get a cold joint: a full-depth plane of weakness in a spot you didn't choose. Critically, that window doesn't get longer because your slab is bigger — a 100 sq ft patio and a 1,200 sq ft driveway both have to be placed inside roughly the same hour and a quarter. The work scales; the time doesn't.
| Project | Sq ft | Cubic yards | Crew at DIY rate | Crew at pro rate |
|---|---|---|---|---|
| 10×10 patio, 4 in | 100 | 1.23 | 1 | 1 |
| 4×20 walkway, 4 in | 80 | 0.99 | 1 | 1 |
| 10×12 shed pad, 4 in | 120 | 1.48 | 2 | 1 |
| 20×20 single garage, 4 in | 400 | 4.94 | 4 | 2 |
| 24×24 two-car garage, 4 in | 576 | 7.11 | 6 | 3 |
| 12×40 driveway, 5 in | 480 | 7.41 | 6 | 3 |
| 20×40 double driveway, 5 in | 800 | 12.35 | 10 | 5 |
| 24×50 driveway, 5 in | 1,200 | 18.52 | 15 | 8 |
Assumes a 75-minute place-and-screed window, a DIY rate of about 1 cubic yard per person per hour, and an experienced-crew rate of about 2. The rates are estimates — see the caveats below — but the shape of the result isn't sensitive to them.
A patio is one person. A two-car garage floor is six people working simultaneously, all of whom know what they're doing, for the entire window, with no breaks. Most people considering a DIY garage floor are imagining themselves and a friend — two people at the DIY rate place roughly 2.5 cubic yards inside the window, and the slab needs 7.11. They get a third of the way across, the first third begins to set, and the result is a floor with cold joints and a finish that got away from them. No amount of preparation fixes this; it's arithmetic, and it's the single best predictor of whether a project is a DIY project.
Placing is only the first clock. After screeding, bleed water has to evaporate before floating begins — float too early and you work water back into the surface, weakening it. On a large slab that window opens and closes at different times in different spots (the sunny end, the windy edge, the shaded corner), so you're chasing a moving boundary and need enough finishers to keep up.
Finish type sorts projects almost as cleanly as volume does. A patio or shed pad gets a broom or light float finish with hand tools. A garage floor wants a hard, steel-troweled finish, which realistically means a walk-behind power trowel — hand-troweling 576 sq ft to a hard finish inside the window isn't achievable for most crews, and a power trowel is heavy, torque-driven, and not a rental you learn on: run it too early and it tears the surface, too late and it burns it, held in one place and it digs a depression you can't remove. If the project calls for a hard-troweled finish and nobody on site has run one before, that's a fail on this gate independent of the crew-size math.
Heat, wind, and low humidity accelerate surface drying — a hot, dry, breezy day can cut the working window in half, and wind is the most underestimated of the three. Direct sun sets edges faster than the field. Fast-setting or accelerated mixes are correct for post holes and wrong for flatwork. Poor truck access means wheelbarrowing instead of chuting, and every yard costs several trips the clock doesn't pause for. A pump you didn't book converts an impossible pour into a routine one, but it's a scheduled service, not something arranged on the day.
Crew needed = cubic yards ÷ 1.25, at a DIY pace of roughly one cubic yard per person per hour within a 75-minute window. Under 2 people: comfortably DIY. Three to four: possible with experienced help and good access. Five or more: you're hiring, sectioning the pour, or failing. Sanity-check the volume itself with square feet ÷ 80 ≈ cubic yards at 4 inches thick.
The verdict, by project
| Project | Structural | Legal | Clock | Verdict |
|---|---|---|---|---|
| Walkway, stepping stones | Pass | Pass | Pass | DIY — the clearest yes on the list |
| Patio up to ~200 sq ft | Pass | Usually pass | Pass | DIY with a helper |
| Shed pad | Pass | Usually pass | Pass | DIY — watch for a turndown edge |
| Patio over ~400 sq ft | Pass | Usually pass | Marginal | Hybrid — split the job, see below |
| Garage floor, replacement | Pass if floating | Permit likely | Fail | Hire, or hybrid at minimum |
| Garage floor, monolithic | Fail | Fail — inspected | Fail | Hire |
| Driveway | Pass | Fail at the apron | Fail | Hire, or hybrid in sections |
| Steps | Fail — life safety | Permit likely | Pass | Hire unless experienced |
| Retaining wall under 3 ft | Pass | Usually pass | Pass | DIY with drainage done properly |
| Retaining wall over 3–4 ft | Fail | Fail — engineering | Varies | Hire — not a close call |
| Footings, piers, stem walls | Fail | Fail — pre-pour inspection | Varies | Hire |
Projects rarely fail on exactly one gate — the things that make concrete structural also tend to make it inspected and large. The large patio and the replacement garage floor are exactly where the gates disagree, and they're the two projects worth thinking hardest about.
What failure actually costs
Most DIY mistakes are reversible at the cost of materials. Concrete isn't — it's heavy, bonded to whatever's under it, destructive to remove, and the debris is charged by weight at the landfill. A cubic yard weighs about two tons.
| Project | Cubic yards | Rubble to remove | What makes removal hard |
|---|---|---|---|
| 10×10 patio | 1.23 | 2.5 tons | Little — open on all sides, thin, usually unreinforced |
| 24×24 garage floor | 7.11 | 14.2 tons | Inside a building, one door, carried out by hand or barrow |
| 12×40 driveway | 7.41 | 14.8 tons | Thicker and reinforced — mesh and rebar cut as you go |
| 20×40 double driveway | 12.35 | 24.7 tons | A machine job and a series of dumpsters |
| Footings | Varies | — | Can't be removed without first supporting everything above |
For a patio, the worst realistic outcome is a weekend and a few hundred dollars spent on a slab you're not proud of — bounded and small. For a driveway or garage floor, the worst realistic outcome is a weekend and several thousand dollars spent on a slab with cold joints and a failed finish, followed by paying a contractor to demolish and haul away fifteen tons of material before rebuilding the thing you were trying to save money on — roughly double the cost of hiring it out in the first place. For a footing or retaining wall, the downside isn't bounded the same way, because the failure damages something other than itself.
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The middle options nobody offers you
Framing this as a binary is the biggest missed opportunity in it. The job divides cleanly, and the division follows exactly the line the three gates draw: excavation, base prep, compaction, forming, and reinforcement have no clock at all — take a week, stop for rain, redo a form, measure twice. Placement and finishing are the only parts under time pressure, and they're the parts that need a trained crew of the right size at one moment.
| Split | How it works |
|---|---|
| You prepare, a crew pours and finishes | The highest-value split. You handle excavation, base, forms, and rebar on your own schedule; a crew arrives on pour day and does the timed part. Ask for a "pour and finish" or "labor only" price. |
| Hire a finisher for the day | You supply the concrete and the muscle; one experienced finisher runs the finish and directs the pour, often for a day rate. Works when you have enough bodies but nobody who knows what good looks like. |
| Pour in sections on separate days | A large slab is divided into properly jointed bays, each poured as its own complete pour. A 12×12 bay comfortably passes the clock gate with two people. The joint has to be designed — bulkhead forms and dowels — not improvised, and this doesn't apply to a monolithic structural slab. |
| Contractor does the base, you do the rest | The inverse split — right when the base is the hard part: deep fill, expansive clay, drainage work, or anything needing machine compaction and testing. |
| Buy the materials, hire the labor | You order and pay for concrete and base material directly; the contractor bills labor only. Gives visibility into the mix design and batch tickets, but moves material risk — including a short order — onto you. |
If you hire, hire well
Deciding to hire is half the decision — the other half is not getting a bad version of the thing you just paid for. Verify rather than ask: check the license with the issuing state board by number, request the certificate of insurance from the insurer directly (not a copy from the contractor), confirm workers' comp covers everyone on your property, and confirm right-of-way registration if the work touches the apron.
| Contract term | What to require |
|---|---|
| Thickness | A number, in inches, for each element — not "standard" |
| Strength | A specified PSI at 28 days — 3,000–4,000 for residential flatwork |
| Reinforcement | Type, size, spacing, and support on chairs at the correct depth — not laid on grade |
| Base | Material, depth, and that it's mechanically compacted |
| Control joints | Spacing, depth (about ¼ of slab thickness), and timing — cut too late, they don't work |
| Curing | What method, for how long. If the answer is nothing, keep looking |
| Batch tickets | That you receive them — they document what was actually delivered |
| Payment schedule | Modest deposit, balance on completion |
| Warranty | In writing, with a term, and specific about what it covers |
All concrete cracks. Any contractor who promises a slab that will never crack is either inexperienced or telling you what you want to hear. The right answer is specific: control joints at a stated spacing so cracking occurs there rather than randomly, and a warranty covering cracks beyond a stated width or outside the joints. A contractor who volunteers that distinction unprompted is demonstrating the knowledge you're paying for.
Red flags: leftover material from another job, door-to-door solicitation with pressure to decide today, cash-only or a large cash deposit, no written contract or one that skips thickness and strength, a quote substantially below the others with no explanation, and vagueness about joints and curing — the two things that separate a slab that lasts from one that doesn't.
Quick reference
| Working window, standard mix | 60–90 minutes; halved by heat, wind, or low humidity |
| DIY place-and-screed rate | About 1 cubic yard per person per hour |
| Experienced crew rate | About 2 cubic yards per person per hour |
| Weight of one cubic yard | About 4,000 lb — 2 tons of rubble if it comes back out |
| Square feet per cubic yard at 4 in | 81 — round to 80 |
| Control joint spacing | About 2–3 times slab thickness in inches, measured in feet |
| Control joint depth | About one quarter of slab thickness |
| Max riser variation in a stair flight | Commonly 3/8 inch — verify locally |
| Retaining wall permit threshold | Commonly 3–4 ft — verify locally |
| Residential flatwork strength | Typically 3,000–4,000 PSI at 28 days |
Use the calculator below to size whatever you're pouring, then divide by 1.25 to get your crew-size check — pre-filled at a 12×40, 5-inch driveway:
A 12×40 ft slab poured 5 in thick needs about 367 80-lb bags of concrete, or 8.15 cubic yards of ready-mix — that's roughly 30,000 lb of concrete.
The question is almost never whether you could learn to do this — concrete work is learnable, and plenty of people have taught themselves on a patio and gone on to do good work. The question is whether this particular project gives you room to learn. A patio does: small enough for one person, forgiving enough that a mediocre result still functions, cheap enough to break out if it comes to that. A garage floor doesn't — not because it's harder, but because seven cubic yards has to be placed in seventy-five minutes by people who already know what they're doing, and there's no version of that afternoon where you learn as you go. If you want to do concrete work yourself, start where the gates all pass and build up — and when a project fails one, remember the choice isn't only hire or DIY. Do the week of work that has no clock. Buy the hour that does.
Common questions
How do I know if a concrete project is structural?
Ask one question: does anything bear on it that would be damaged if it moved? A patio only carries foot traffic, so it's not structural. A footing, a retaining wall over about 3 to 4 feet, or a monolithic garage slab carries the building or the soil behind it, so it is — and that alone is usually reason to hire it out.
Can I pour my own driveway apron?
Often no. The apron between the street and your property line sits in the public right-of-way, and most agencies require a licensed, right-of-way-registered contractor for that section because of bonding and insurance requirements — regardless of your skill. You may be free to pour the rest of the driveway yourself and legally barred from the twelve feet nearest the street.
How many people do I need to pour a concrete slab myself?
Roughly your cubic yards divided by 1.25, at a DIY placing rate of about one cubic yard per person per hour inside a 75-minute working window. Under two people is comfortably DIY; five or more means hiring, sectioning the pour into smaller bays, or failing partway through.
What is the 90-minute rule for concrete?
Standard concrete has a working window of roughly 60 to 90 minutes at moderate temperatures, shorter in heat, wind, or direct sun. The entire pour has to be placed and screeded inside that window, because concrete placed against concrete that's begun to set doesn't bond — it leaves a cold joint, a full-depth plane of weakness.
Is there a middle option between hiring a contractor and DIY?
Yes, and it's usually the best value. Excavation, base prep, forming, and rebar have no clock — you can do that part yourself on your own schedule. Only placing and finishing are timed. A common split is doing the prep work yourself and paying a crew for a "pour and finish" day, which captures most of the labor saving while eliminating the clock risk entirely.