What should I ask a concrete contractor before hiring them?

Start with the licence, then ask how they will build the slab. A good concrete contractor answers the technical questions without hesitation: how thick, what goes under it, what mix they order, where the joints go, and how they cure it. Ask every contractor the same questions, write down the answers, and compare quotes on the same specification.

Licence and paperwork

Are you licensed, and in what class? Virginia's Code says: "No person shall engage in, or offer to engage in, contracting work in the Commonwealth unless he has been licensed under the provisions of this chapter."^[1] The class has to fit the price: a Class C contractor works on single contracts over $1,000 but less than $30,000, and a Class B contractor on contracts of $30,000 or more but less than $150,000.^[2]

Which specialty covers concrete? The Board for Contractors defines concrete contracting (CEM) to include placing, finishing, curing, sawing and sealing concrete and building its forms, and says the CBC, RBC and H/H classifications also cover that work.^[3] Home improvement (HIC) licensees cover repairs and improvements to dwellings, which includes patios and driveways that do not require a permit under the building code.^[3]

Check it yourself. DPOR warns that a licence number on an advertisement or business card does not necessarily mean the licence is valid, and the Board can also tell you about past complaints and disciplinary actions.^[5]

Who calls 811 and who gets the approvals? Virginia 811 says your contractor is responsible for contacting Virginia 811.^[7] For a new driveway onto a state-maintained road, Virginia's access management rules say the property owner shall obtain an entrance permit,^[8] so agree in writing who applies. DPOR advises against pulling permits yourself, because the permit holder becomes the general contractor and takes on responsibility for the overall job.^[5]

How they will build it

How thick, and on what base? Ask for the thickness in writing and what they do to the ground first: removing soft soil, adding and compacting gravel, and setting the slope so water runs away from the house.

What concrete will you order? Outdoor slabs in Virginia go through freeze and thaw, and thickness depends on the load. Quikrete says 4 inches is sufficient for passenger cars, and a thickness of 5 or 6 inches is recommended where trucks and other heavy vehicles will use the driveway.^[12] Ask for the thickness, the specified strength in psi and whether the mix is air-entrained, and have all three on the quote.

Where do the joints go, and when are they cut? Most cracks in a new slab trace back to jointing, the base, water and curing, so ask for the joint layout before the pour. As a yardstick, Quikrete's instructions cut 1-inch control joints into the slab every 6 to 8 feet,^[10] and VDOT's sidewalk specification divides the slab into sections approximately 5 feet long with control joints that extend into the concrete at least 1/4 of the depth.^[9] Ask too about a strip of joint filler where the slab meets the house, a walk or a curb; VDOT requires preformed joint filler between its concrete sidewalk and any adjacent fixed structure.^[9] If they saw the joints, ask when, since late cuts let the slab crack first.

Do you add water on site? Some water may be added when the truck arrives, within the mix design. Ask to see the delivery ticket and what it says about water, and do not ask for a wetter mix; extra water weakens concrete and makes cracking more likely.

How will you cure it, and in what weather will you pour? Quikrete says curing should continue for 5 days in warm weather at 70 F or higher, or 7 days in colder weather at 50 F to 70 F.^[11] Ask what they do on a hot, windy day: VDOT's specification says care shall be taken in hot, dry, or windy weather to protect the concrete from shrinkage cracking by applying the curing medium at the earliest possible time after finishing operations.^[9] And ask what they do before a freeze: VDOT has its contractor prevent the temperature at the surface of the concrete from falling below 40 degrees F during the first 72 hours after placement.^[9] For timing after the pour, see how long new concrete should cure before you drive on it.

What does your warranty cover? No contractor can promise a slab that never cracks. A useful warranty says which cracks, settling or surface flaking will be repaired, and for how long. Why new concrete cracks explains which cracks are normal.

The contract and payments

For residential work, Virginia's Board for Contractors requires a written contract that includes when work is to begin and the estimated completion date, the total cost, the amounts and schedule of progress payments including the down payment, a list of the specified materials and work, a statement that the contractor will comply with local permit, inspection and zoning requirements, the cancellation rights of the parties, and the contractor's name, address, licence number, class and specialty.^[4] It also says any change to cost, materials, work or completion date must be in writing and signed by all parties.^[4]

DPOR's rule of thumb is a deposit of no more than 10% of the total price or $1,000, whichever is less, and it says do not pay 100% of the bill until the job is 100% complete.^[5] If something goes wrong later, a single Recovery Fund claim is limited to $30,000, and a claim requires a court judgment against a licensed contractor for improper or dishonest conduct, and the work must have been for your residence in Virginia.^[6] The Fund covers losses from the improper or dishonest conduct of a licensed residential contractor, and a claimant who has a judgment against a bonded contractor must seek recovery through the bond.^[6]

For what drives the price, read what a concrete slab costs in Virginia.

Stop and call a pro if

These are signs to stop, or to choose a different contractor:

• The contractor will not give a licence number, or the number does not check out.
• They want cash, a large deposit, or a signature today for a special price.
• They plan to dig without a locate ticket.
• The slab is meant to carry a structure and nobody has mentioned a design or the building office.
• The quote leaves out thickness, mix, joints or curing, so you cannot compare it with others.

If you decide to pour a small pad yourself instead, see how to pour a small concrete slab.

Finding a contractor in Virginia

Loclis lists DPOR-licensed businesses from the state register with their licence number, class and a link to DPOR's lookup. Look up concrete contractors in Blacksburg, browse concrete and flatwork, or see all concrete and hardscaping answers.

Describe the job once and licensed local concrete businesses quote it.