Concrete installation: what to know

What the job involves, what changes the price, and what to ask a pro.

What concrete installation is

Concrete installation means building a new slab, walk, floor or pad on prepared ground. People usually call when they are adding a garage floor, a shed pad, a walkway or a new basement floor, because the finished result depends on the base and forms as much as the pour itself.

Signs you need it

  • The spot you want to pave is bare dirt or loose gravel that turns to mud or dust and cannot take a load
  • A shed, hot tub, generator or equipment pad sits on soil that shifts, and it needs a level reinforced base
  • You plan an addition, enclosure or garage where a finished floor must be poured to a set height
  • Water runs toward the house from a yard or path that needs a new surface with a slope pointing away from the building
  • An old slab was removed or washed out and the area needs a new base and surface poured in its place
  • A dirt path wears into ruts and needs a poured walk that holds up to foot traffic and a wheelbarrow

What the pro does

  • Mark the layout and set grade stakes, then dig out topsoil and soft fill to the depth the slab design calls for
  • Place and compact a gravel base in layers, and lay a vapor barrier under the slab where moisture could rise through it
  • Build wood or metal forms to the finished height, pitched slightly so water runs off and away from any building
  • Set rebar or welded wire mesh on chairs so it sits in the middle of the slab, then place the mix and strike it level with a screed board
  • Bull float the surface, then finish it with a broom or trowel and cut control joints before the surface sets
  • Keep the new slab damp and covered through the first days of curing, and strip the forms once the edges hold their shape

What changes the price

Every job is different, so we do not publish prices. These are the things that move the quote up or down.

  • Slab size and thickness, since a garage floor needs far more concrete and reinforcement than a backyard walk
  • How much excavation and base material the site needs, especially on soft ground or a slope
  • Whether the slab sits at grade or is elevated, and whether the edges need thickening where they carry a wall
  • Truck and pump access, and how far the mixer can reach the pour spot without a long wheelbarrow run
  • The finish you pick, from a standard broom finish to added color or a textured look
  • Reinforcement chosen for the load, such as fiber in the mix alone or rebar with mesh for vehicles
  • Removal and hauling of any old slab or debris that has to go before the new one can be poured

What a written quote should spell out

  • Slab dimensions, thickness and the concrete mix grade named in the proposal
  • Base depth, the gravel type used and the compaction method, with who handles the subgrade
  • The reinforcement type, such as rebar, welded wire mesh or fiber, and whether a vapor barrier is included
  • Control joint layout, edge detail and the finish type for the surface
  • Whether forms, pump service and cleanup of excess concrete are included, and who removes them
  • The curing method and whether a curing or sealing compound is applied after the finish

Questions to ask before you hire

  • How deep will the gravel base be, and will you compact it in layers with a plate compactor or roller?
  • Where will the control joints go, and how do they line up with the shape and corners of the slab?
  • How much slope will the surface have, and which direction will the water flow?
  • What mix and reinforcement will you use for the load this slab has to carry?
  • Who checks the grade and the forms before the truck arrives, and what happens if something is off?
  • What is your plan if rain or a cold snap is forecast on the day of the pour?
  • How long will the forms stay on, and when can the slab take foot traffic and then vehicles?

Red flags

  • Plans to pour directly on soil with no compacted base under the slab
  • Says the slab will not crack and skips the control joints entirely
  • Adds water to the truck on site to make the mix easier to place, which weakens the finished concrete
  • Pours in freezing weather with no blankets, heater or curing plan for the slab
  • Sets forms or pours without checking that the grade drains away from the building

What you can do yourself

A homeowner can clear the site, dig out topsoil and set the gravel base on a small job such as a shed pad if they rent a plate compactor. Hire a pro for the grading, forms, reinforcement and the pour itself, because a slab that is out of level or badly finished is hard to fix later. Concrete is heavy and alkaline, so wear gloves, eye protection and long sleeves around wet mix.

Licenses and permits

Concrete flatwork is commonly done by licensed contractors, and many areas require a permit for new slabs, especially driveways, large pads or work tied to a building. Check with your state or local licensing agency and your local building department before work starts.

Concrete installation questions

How long does a new slab need before I can use it?

Light foot traffic is usually fine after a day or two, while cars and heavy loads should wait longer. Concrete reaches most of its full strength over about four weeks, so ask the crew for the curing schedule for your slab.

Why did my new slab crack at all?

Some fine cracking is normal as concrete cures and shrinks, and control joints are there to guide cracks into straight lines. Wide, uneven or growing cracks usually point to a weak base, poor drainage or too little reinforcement.

Do I need to be home for the pour?

You do not have to watch every step, but someone should approve the forms and grade before the truck arrives. Ask the pro who will be on site during the finishing and who to call if the weather changes.

About this guide

This national guide is written and checked by infinibell. Rules and conditions differ by place, so local pros are credited on guides for the cities they serve, not on national ones.

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