Why store-bought caulk pops out and what works instead
We see the same repair all over Aurora. A homeowner squeezes a bead of hardware store caulk into a driveway crack in the fall. By the following spring it's cracked, shrunken, and peeling out in a long strip. The crack underneath is wider than it was.
Concrete cracks move. In winter, the slab shrinks in the cold and the crack opens. In summer, it closes up as the slab warms and expands. Cheap caulk can't keep up with that. It tears at the edges, loses its bond, and lets water in. Then the freeze-thaw cycle does the rest: water enters the crack, freezes, expands, and pries it open a little more.
We fix it differently. We cut the crack out with a router or saw to give the filler a clean, wider channel to grip. We blow it out, dry it, and fill it with a flexible polyurethane sealant that stretches and shrinks along with the slab. For cracks that no longer move, we can use epoxy, which bonds the two sides back together. Pricing runs $4 to $12 per linear ft. A Cracks across a typical 2-car driveway (about 75 linear ft) typically lands at $300 to $900. Crack repair is the starting point in our concrete repair services.
Which cracks need work now, and which can wait?
Not every crack deserves a repair. Here's how we sort them when we walk the slab.
Call soon if you see
- A crack wide enough to slide a nickel or a pencil into
- A crack where one side sits higher than the other
- Cracks that have gotten wider or longer since last year
- A crack that lets water in, with stains or damp spots along it
- Cracks that are branching or breaking off pieces near an edge
Usually safe to watch
- Hairline cracks, no wider than a credit card edge, that have stayed the same
- A crack right along a control joint, where cracking was planned
- Fine surface crazing with no depth to it
- Cracks in a slab that is being replaced this season anyway
Types of cracks and how we handle each one
Hairline shrinkage cracks
Concrete shrinks a little as it dries, and thin cracks often appear in the first year. They are usually harmless. If they stay hairline-thin, a penetrating concrete sealer across the whole slab is often enough to keep water out, rather than filling each line.
Moving cracks
A crack that opens in winter and closes in summer is still moving. It needs a flexible filler, so we use polyurethane sealant. It stays rubbery, handles the seasonal swing, and bonds to the sides of the routed channel. This is the most common repair on driveways and walkways.
Dormant structural cracks
Some cracks open once, usually from a load or a one-time settlement, and then stop. In a slab that isn't moving, epoxy can weld the two sides back together and restore strength. We don't use epoxy on a crack that is still shifting, because it is rigid and will just crack again next to the repair.
Cracks that mean the base failed
A crack with one side sunken, a series of cracks running across a panel, or cracks that keep returning after a repair, usually point to a problem under the slab. Soil washed out, clay swelled, or fill was never compacted. Filling the crack won't fix that. A sunken panel can often be lifted with concrete leveling. If the slab has broken into pieces, replacement is the better call.
How we repair a concrete crack
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Read the crack
We check the width, the length, whether the sides are level, and whether it moves. We also look at where the water goes, since drainage is often the reason a crack formed.
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Rout the crack
We cut a clean channel along the crack, usually about a quarter to a half inch wide. This gives the filler something to grip and removes loose, crumbling edges.
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Clean and dry
We blow out dust and debris with compressed air. Anything left in the crack stops the sealant from bonding, and wet concrete does the same.
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Fill with the right material
Moving cracks get flexible polyurethane. Dormant structural cracks get epoxy. We tool the surface flush so water runs off instead of pooling.
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Cure and protect
Sealants need time before traffic. We tell you how long for each one. On a driveway, a penetrating sealer over the whole slab protects the repair and the surrounding concrete.
What affects the price of crack repair
Most crack work runs $4 to $12 per linear ft. Here's what moves a job up or down.
- Total length
Price follows the linear feet of crack. Many jobs have a minimum charge, so a single short crack costs more per foot than a driveway full of them.
- Crack width and depth
Wide or deep cracks need more material and sometimes backer rod, which holds the sealant at the right depth.
- Material
Flexible polyurethane suits most cracks. Epoxy costs more and only works on cracks that aren't moving.
- Site prep
Oil stains, old caulk, and packed dirt have to be cleaned out before the sealant goes in. A cracked slab with lots of old failed repairs takes more time.
- Base problems
If the slab is sunken or rocking, leveling it first adds cost but keeps the crack from reopening. Leveling is priced at $4 to $8 per sq ft.
Crack repair through Aurora’s seasons
Winter
Cracks are at their widest in cold weather, which is when a flexible sealant has to stretch the most. But sealants and epoxy need dry, above-freezing conditions to cure, so most repairs wait for a warm stretch.
Spring
Spring shows you which cracks grew over winter. Wait for the slab to dry out, then repair them before summer storms bring more water.
Summer
Summer is a good time to repair cracks. We work early, before heat and wind make the materials set too fast.
Fall
Fall is the ideal window. Repair cracks in September or October, let the sealant cure, and add a sealer before the first snow so water and salt stay out.
Aurora soil, salt, HOAs, and permits
Expansive clay soil
Clay under Aurora slabs swells and shrinks, which makes cracks open and close and sometimes lift one side. That's why flexible sealant matters and why we look for a base problem when cracks keep returning.
Deicing salt
Salt carried home on tires gets into open cracks and speeds up damage. A repaired crack and a sealed surface keep it out. If the surface is already flaking, resurfacing may be the better fix.
HOA approval
Crack repair rarely needs HOA approval, but visible patching on front walks or driveways may be worth a quick check with your board, especially if a color match matters.
City of Aurora permits
Private work on public right-of-way concrete, like the sidewalk or curb in front of your house, needs a city permit and has to meet city specs. Driveways, detached driveways, and aprons are the owner's to maintain. Confirm current rules with Aurora Public Works.
Concrete Crack Repair FAQs
How much does concrete crack repair cost in Aurora?
Most crack repair runs $4 to $12 per linear ft. A Cracks across a typical 2-car driveway (about 75 linear ft) typically costs $300 to $900. Minimum charges apply to small jobs.
Why does caulk from the hardware store fail?
It doesn't flex enough. Concrete cracks open and close with the seasons, and cheap caulk tears or pulls loose, usually within a winter. We rout the crack and use a flexible polyurethane sealant made for the movement.
When do you use epoxy instead of polyurethane?
Epoxy is for cracks that have stopped moving and need to be bonded back together. Polyurethane is for cracks that still move. Using epoxy on a moving crack means it will just crack again beside the repair.
Will the crack come back?
A sealed crack should hold if the cause was shrinkage or normal seasonal movement. If the base has failed or the slab keeps shifting, the crack can reopen, so we check for that first.
Is a hairline crack a problem?
Usually not. Thin shrinkage cracks that stay the same width are cosmetic. Keep an eye on them, and seal the slab so water stays out.
Should I repair the crack or replace the slab?
Repair cracks that are stable and in a solid slab. Replace when the slab is broken into pieces or the base has failed. Our repair vs replace guide covers how to tell.