12 Questions to Ask a Concrete Contractor Before You Hire
Before hiring a concrete contractor, ask about the PSI mix and slump, reinforcement type and spacing, base depth and compaction, control joint plan, curing method, and — in cold climates — air entrainment. The answers separate crews who build slabs that last 30 years from crews whose work cracks in three. Bring this list to every estimate.
Credentials and Track Record
1. Are you licensed and insured? Why it matters: Concrete work involves heavy equipment and multi-ton deliveries on your property; licensing rules vary widely by state. Good answer: License number (where required) plus current liability and workers’ comp certificates, offered without hesitation. Verify using our license verification guide and the FTC’s hiring-a-contractor checklist. Bad answer: “We don’t need a license for concrete here” with no insurance paperwork offered.
2. Can I see past projects like mine — including older ones? Why it matters: Fresh concrete always looks good; work that’s 3–5 years old shows whether base prep and jointing hold up. Decorative finishes (stamped, exposed aggregate) are specialized skills. Good answer: Addresses you can drive past, plus photos of your exact finish. Bad answer: Only stock-looking photos, nothing older than this season.
The Mix and Reinforcement Questions
3. What PSI mix will you order, and what slump? Why it matters: PSI is the concrete’s design strength; slump measures wetness. Crews sometimes add water on site to make concrete easier to spread — which permanently weakens it. Good answer: “3,500–4,500 PSI for a driveway, around a 4–5 inch slump, and we don’t add water at the truck.” Strength standards come from the American Concrete Institute, whose residential code (ACI 332) governs exactly these specs. Bad answer: “Standard mix” with no number, or “we wet it up so it finishes easy.”
4. Will you use rebar or wire mesh, and at what spacing? Why it matters: Reinforcement holds cracks tight so they don’t widen. Position matters as much as presence — mesh trampled to the bottom of the pour does nothing. Good answer: Specifics: “#3 or #4 rebar on a 18–24 inch grid, on chairs” or “6×6 mesh, pulled to mid-slab” — plus when they’d recommend fiber. Bad answer: “You don’t need anything for a driveway.”
5. In a cold climate: will the mix be air-entrained? Why it matters: Air entrainment — microscopic bubbles that absorb the expansion of freezing water — is the single most important durability spec in freeze-thaw regions, per both the ACI and the Portland Cement Association. Good answer: “Yes, 5–7% air, standard for exterior work here.” Bad answer: A blank look. In the North, that alone disqualifies the bid.
The Base and Jointing Questions
6. What base depth and compaction are included? Why it matters: Bad base is the #1 cause of failed concrete. The slab is only as good as what’s under it. Good answer: Excavation depth, 4–8 inches of specified gravel, and mechanical compaction (plate compactor), all itemized in the bid. Bad answer: “We pour on grade” or a bid that never mentions base at all.
7. What’s your control joint plan? Why it matters: Concrete will crack as it shrinks; joints decide where. Spacing should be roughly 24–36 times slab thickness in inches (8–12 feet for a 4-inch slab), cut to one-quarter depth. Good answer: A sketch or spacing rule, plus whether they hand-tool or saw-cut and when. Bad answer: “We’ll see how it looks.”
8. How thick will the slab be — everywhere? Why it matters: 4 inches is standard for walks and patios; 5–6 inches where vehicles load, especially driveway aprons. Good answer: Thickness stated in the contract, with thickened edges where needed. Bad answer: A nominal “4 inches” with no written commitment.
The Pour-Day and Aftercare Questions
9. How will you cure the concrete? Why it matters: The first 72 hours of moisture retention largely determine surface durability for the life of the slab. Good answer: Curing compound sprayed at finish, or wet cure/blankets, named specifically. Bad answer: “It dries on its own.”
10. What’s your weather contingency plan? Why it matters: Concrete waits for no one — rain ruins fresh finishes and pouring on frozen ground guarantees failure. Good answer: “We reschedule below 40°F or ahead of rain; if a pop-up shower hits, we have plastic on the truck.” Rescheduling is discipline, not flakiness. Bad answer: “We pour rain or shine.”
11. Is sealing included, and what’s the recommended schedule? Why it matters: Sealing is the maintenance that doubles slab life in freeze-thaw climates. Good answer: Whether first sealing is in the bid, plus a 2–5 year reseal schedule and a salt warning for the first two winters. Bad answer: “Concrete doesn’t need sealing.”
12. What warranty do you offer, in writing? Why it matters: Hairline cracks are normal; widespread cracking and settling are workmanship failures. Good answer: A written 1–3 year workmanship warranty defining coverage. Bad answer: “Concrete cracks, nothing we can do.”
What Red Flags Should End the Conversation?
- A bid quoting price per yard of concrete only — labor and prep are the real product.
- No base prep itemized anywhere in the quote.
- Can’t name a PSI, slump, or air content.
- Demands a large cash deposit upfront (the FTC flags this pattern in its contractor guidance).
- Pressure to skip permits.
Suspiciously cheap labor is its own warning: BLS wage data shows skilled finishers command solid wages everywhere, so a far-below-market bid means inexperienced labor or skipped prep. Sanity-check pricing with the concrete cost guide and compare bids on identical specs using our bid comparison worksheet — and vet the company itself with how to find a concrete contractor.
Frequently Asked Questions
What are the most important questions to ask a concrete contractor? Base depth and compaction, PSI mix and air entrainment, reinforcement type and spacing, control joint plan, and curing method. Those five determine whether the slab lasts 30 years or cracks in three.
What PSI should residential concrete be? Typically 3,500–4,500 PSI for driveways and exterior flatwork, 3,000+ for patios and walks. In freeze-thaw climates, the mix should also be air-entrained at roughly 5–7%.
Is rebar or wire mesh better for a driveway? Either works when placed correctly — rebar for heavier loads, mesh or fiber for standard slabs. What matters most is position: reinforcement must sit mid-slab on chairs, not get trampled to the bottom.
How long before I can use new concrete? Foot traffic in 24–48 hours, vehicles after about 7 days, full design strength near 28 days. Curing method in the first 72 hours largely sets the surface’s lifetime durability.
What’s the biggest red flag in a concrete contractor’s answers? Vagueness about base prep. Everything visible looks fine on day one — the base underneath is what fails, and contractors who won’t itemize it usually plan to skimp on it.
Last updated: June 2026. For informational purposes only.
Sources: American Concrete Institute · Portland Cement Association · FTC: Hiring a Contractor · U.S. Bureau of Labor Statistics, Occupational Employment and Wage Statistics