Hiring a concrete contractor is uncomfortable precisely because you cannot inspect the thing you are actually buying. Once the pour is done, the base underneath it is invisible forever. You are, in a very literal sense, paying for work you will never see — which is why the questions you ask beforehand matter more here than in almost any other trade.
Start with the base, because it is where every corner gets cut. Ask directly: how deep are you excavating, what granular material are you putting down, and how are you compacting it? A contractor who is doing it properly will answer immediately and specifically, because they price it and they think about it. A contractor who is not will get vague, change the subject to the finish, or tell you the ground here is fine as it is. On Richmond delta silt or a Port Coquitlam lot that ponds water, the ground is very much not fine as it is.
Then ask about drainage and grade. Where is the water going to go once this surface is in? A real answer describes a fall away from the house, a defined discharge point, and — behind any wall — drainage rock and weeping tile. If your contractor has not looked at your downspouts, your low spots, or what happens to your yard in November, they are quoting a shape, not a job.
Get the estimate in writing and read what is in it. It should say the slab thickness, the base depth, the reinforcement (mesh or rebar and where), the control joint layout, the finish, the sealer, and what happens to the debris from the old surface. It should say what is included and what is not. A one-line quote with a number on it is not an estimate, it is a hostage situation waiting to happen — because everything not written down becomes a change order once your driveway is a hole in the ground.
Ask for proof of insurance and expect to receive it without an argument. Concrete work involves heavy equipment, excavation, and materials moving around your property, and if an uninsured crew has an accident on your land, that becomes your problem. Ask about WorkSafeBC coverage too. A legitimate contractor will send the documents before you have finished asking; a reluctant one has just told you something important.
Now the price. If one quote comes in dramatically below the others, do not congratulate yourself — find out what it leaves out. It is almost always base depth, reinforcement, or drainage, because those are the three things you cannot see and the three things that decide whether the slab lasts twenty-five years or five. A driveway is not a thing you want to buy twice. In our experience the cheap quote and the expensive quote usually end up costing the same amount of money; the cheap one just spreads the payments out over two contractors.
Finally, look for signs of a business that will still be there. An incorporated company, a fixed phone number, a real service area, references from jobs near you, and someone who will tell you honestly when a repair will do instead of pushing a replacement. Ask what they will not do — a contractor who admits the limits of their trade and calls in an engineer when a wall needs one is telling you they intend to be around long enough for the outcome to matter to them.
We have been doing this in Metro Vancouver for over 8 years and we are happy to be measured against every question above. Ask us all of them. Ask the next contractor too — and hire whichever one answers them properly.