Concrete — problems, causes and costs

Most concrete trouble starts underneath the slab or before the pour, not in the surface you can see. Find what you’re seeing below. Several of these you can handle yourself, and we say which ones.

877-360-4657 What concrete work costs

Quick answerConcrete fails in four main ways: it cracks as it cures or moves, it sinks when the ground under it compacts, its surface flakes off from freeze-thaw or a poor finish, or it holds water because the grade is wrong. Some of this is normal and cosmetic. Cracks that widen, offset or open with the seasons, and slabs that sink, are movement and worth a closer look.

Everything we have on concrete: what fails, why, what it costs, and which of it you can handle without calling anyone. A lot of the expensive damage is decided before the truck arrives, by the base, the reinforcement, the joints and the weather on pour day.

A flight of poured concrete steps with fallen leaves scattered across the treads — Photo by Uljana Vasiljeva on Unsplash

1Start with what you can see

Often DIYCracks radiating from a cornerFirst-year shrinkage cracks are normal. Cracks that widen or offset are movement. Usually a proDriveway settling near the garageBackfill compacts and the slab follows it down. Lifting often beats replacing. Usually a proSpalling surface flaking offFreeze-thaw damage or a bad finish. Patching a delaminating surface is temporary. Often DIYExpansion joints filled with debrisClear them and refill with flexible sealant so the slab can move where it should. Often DIYWater pooling on the drive after rainA grade issue, not a concrete defect. Near the house it becomes a foundation problem. Tree firstTree roots lifting a sectionCutting roots can destabilize the tree. Get the tree assessed before the slab. Before the pourPour scheduled in extreme heatHot-day concrete cures too fast and cracks. Ask for an early pour and a curing plan. Before you signRebar or mesh unclear in the quoteReinforcement is where cheap quotes get cheap, and you can’t see it afterwards. CostsConcrete cost: what to expect and what to skipWhat drives the price, and which concrete work you shouldn’t be paying for.

2How concrete fails

Failure	Usual cause	First thing to try
Cracking	Shrinkage while curing, missing or packed joints, or movement in the base	Mark the crack ends and watch them through a season before deciding
Sinking or settling	Soil or backfill under the slab compacting or washing out	Check where roof and surface water goes; ask about lifting before replacing
Surface flaking (spalling)	Freeze-thaw, a poor finish, or deicer on young concrete	Find out how deep it goes; a delaminating surface needs more than a patch
Standing water	Slab pitched flat or toward the house, or low spots from settling	Redirect downspouts and regrade the soil at the edges
Lifting and heaving	Tree roots, or frost under a slab with poor drainage	Have the tree looked at before anyone cuts roots

A crack running through a concrete surface — A crack in concrete. Whether it is shrinkage or movement depends on whether it keeps changing. Photo by Sari Crasnich on Unsplash.

Slab sinking, heaving or breaking up?Talk to a local concrete contractor who will look at the base and the drainage, not just the surface.

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3What concrete work costs

The price moves with the area and thickness of the slab, how much old concrete has to be broken out and hauled away, base preparation, reinforcement, access for the truck or pump, finish, and the season. Lifting a sound slab is usually cheaper than replacing it. Prices vary by region, and where a job has a genuine do-it-yourself version we say so rather than quoting a number.

Concrete cost: what to expect and what to skip

4Concrete FAQ

Are cracks in new concrete normal?

Some are. Fine shrinkage cracks in the first year are common and largely cosmetic. Cracks that keep widening, step out of level, or open and close with the seasons point to movement under the slab.

Should I replace or lift a sunken slab?

If the slab itself is in one piece and sound, mudjacking or foam lifting is usually cheaper than tearing it out. Badly broken or spalling slabs are better replaced.

Can I seal over a flaking surface?

Sealer can help protect sound concrete. Once the surface is delaminating, sealing or patching over it is temporary, because the layer underneath is what failed.

What should a concrete quote spell out?

The slab thickness, base preparation, the reinforcement and its spacing, joint layout, the finish, and the curing plan. Ask for it in writing, because most of it is hidden once the concrete is poured.

Written by Jaylan Jones. I Like To Exterior Services earns a referral fee when a call connects to a contractor. See our business-model disclosure.

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