Questions to Ask a Concrete Contractor Before You Hire

"What are you doing to the ground before you pour?"

Ask this first, because the answer predicts more about the finished slab than anything else on the quote. Concrete is strong in compression and weak in tension — it does not span voids. Whatever the base does over the next ten winters, the slab does too. Settlement under one corner is what turns a hairline crack into a step you can catch a toe on.

A contractor who takes base preparation seriously will describe it without being prompted: how far down they excavate, what unsuitable soil gets removed, what granular material goes back in, and how it is compacted — in lifts, with a plate compactor or roller, not just raked level and driven over. Ask how deep the excavation goes and how thick the compacted base will be. A quote that gives you a pour price with no excavation or base line item is not a cheaper version of the same job; it is a different job.

"What mix are you using, and how thick is the slab?"

Concrete is specified by compressive strength, and residential flatwork does not all get the same mix. A patio and a driveway that will carry vehicles are different loads, and in any climate with freeze-thaw cycles, exterior concrete generally needs air entrainment — microscopic air voids that give freezing water somewhere to expand — plus a strength appropriate to that exposure. Ask what strength is being ordered and whether the mix is air-entrained for exterior use.

Thickness and reinforcement belong in the same conversation. Ask what slab thickness the quote assumes and whether it includes rebar or welded wire mesh, and if so, how it will be held at the correct height in the pour rather than lying on the ground where it does nothing. Reinforcement does not stop concrete from cracking; it holds the pieces together and in plane when it does. That distinction is worth hearing a contractor make, because it tells you they are describing concrete accurately rather than selling you a promise it cannot keep.

One more question in this group is worth asking bluntly: will any water be added to the mix on site to make it easier to place? Adding water past the design mix raises the water-to-cement ratio and lowers the finished strength. A good crew will tell you they use a plasticizer or adjust the order instead.

"Where are the control joints, and when will they be cut?"

All concrete cracks as it cures and shrinks. Control joints are the plan for where — a deliberate line of weakness that makes the inevitable crack happen straight, at the bottom of a groove, where nobody notices it. A contractor who tells you their concrete will not crack is either inexperienced or managing your expectations badly, and the second is worse.

Ask where the joints will fall and how they were spaced, since joint layout is generally driven by slab thickness and geometry rather than by how the panels look. Ask whether they will be tooled during finishing or saw-cut afterwards, and if saw-cut, how soon — cutting too late lets the slab crack on its own first, which is the most common way a well-poured driveway ends up with a random crack across it. Also ask how the slab is isolated where it meets the house, a garage floor, or existing walkways, so the two can move independently instead of fighting each other.

"Which way does the water go?"

Flatwork is never actually flat. Every driveway, patio, and walkway needs a deliberate slope that moves water away from the building, and the destination matters as much as the direction — sloping neatly toward a neighbour's yard or a spot that puddles against a foundation solves nothing. Ask specifically where the water will go, and what happens to it in the heaviest rain the area gets.

For a driveway that runs toward a garage or a basement entry, ask whether a trench drain or catch basin is included, where it discharges, and who is responsible for connecting it. This is a frequent source of change-order surprises, because drainage is easy to leave out of a quote and expensive to add after the forms are set. Pooling water is also a durability issue, not just an inconvenience: standing water that freezes and thaws repeatedly on a surface will take that surface apart faster than traffic does.

"How is it finished, cured, and protected — and for how long do I stay off it?"

Finish is the part you will actually look at every day, so be specific. A broom finish, exposed aggregate, and a stamped decorative surface are different labour, different cost, and different maintenance. Ask to see completed examples of the exact finish you are buying — ideally ones a few years old, because a new stamped patio and a five-year-old stamped patio are very different photographs.

Curing is the step homeowners never ask about and crews cut most often when the schedule tightens. Concrete gains strength through hydration, not drying, so ask how the slab will be cured — a curing compound, plastic, or wet covering — and what the plan is if the weather turns hot, cold, or wet during the pour or the days after. Then get the practical numbers in writing: when you can walk on it, when you can park on it, and whether a sealer is included, when it would be applied, and how often it needs redoing.

"What exactly does the warranty cover, and what does the quote exclude?"

Because concrete cracks by nature, a concrete warranty is only meaningful if it distinguishes between kinds of cracking. Ask what the warranty says about shrinkage cracks, cracks that show displacement or settlement, spalling and surface scaling, and discolouration — and get the answer in writing rather than as reassurance on a driveway. Ask what would void it, since de-icing salts on young concrete are a common and legitimate exclusion.

Then ask what the quote does not include. The usual gaps on a concrete job are demolition and disposal of the existing slab, unsuitable soil discovered during excavation, drainage work, landscape restoration where the truck and crew worked, and permits where a municipality requires them for driveway or curb-cut work. Ask how additional depth or removal of unexpected material would be priced if it comes up mid-dig. Getting that number before excavation costs nothing; getting it after is a negotiation with a machine idling in your yard.

"Who is pouring it, and what happens if it rains that morning?"

A residential pour is a single unrepeatable day. Once the truck starts discharging, the finishing window is set by the concrete, not by the crew's schedule — which is why crew size and experience show up directly in the surface quality. Ask how many people will be on site, who is running the finishing, and whether the crew are employees or a subcontracted pour-and-finish team. There is nothing wrong with the latter, but you should know who to call about a defect a year from now.

Ask about weather calls too: who decides to postpone, how much notice you get, and whether a deposit is affected. And confirm the coverage questions that apply to any trade — liability insurance, and workers' compensation coverage for everyone on site, which you can verify directly with the provincial or state board rather than taking on trust. Our concrete companies directory sets out the full standard we apply, and the broader version of these checks lives in our guide to licensing and insurance before hiring a contractor.

The short list to take into the quote

• ▸How deep is the excavation, what granular base goes back in, and how is it compacted?
• ▸What concrete strength is specified, and is the mix air-entrained for exterior exposure?
• ▸What is the slab thickness, and is rebar or mesh included and supported off the ground?
• ▸Will water be added on site, or is a plasticizer used to keep the mix at design strength?
• ▸Where do the control joints fall, and will they be tooled or saw-cut — and how soon?
• ▸Which direction does water drain, where does it end up, and is any drain included?
• ▸How will the slab be cured and protected, and what is the hot, cold, or wet weather plan?
• ▸When can I walk on it, when can I park on it, and is sealing included?
• ▸What does the warranty cover, in writing, and what voids it?
• ▸What is excluded — demolition, disposal, unsuitable soil, drainage, landscaping, permits?

Frequently asked questions