How Do You Seal Driveway Cracks, and Is It Worth It?

Sealing driveway cracks is one of the cheapest ways to make a driveway last longer, because it keeps water out of the base underneath, and most cracks up to about half an inch wide can be filled yourself for $15-$60 in materials. Wider cracks, sunken slabs, and spiderweb cracking that covers a large area usually mean the base has failed, which calls for patching, slab lifting, or replacement instead.

Why small cracks matter

A driveway is only as strong as the gravel and soil under it. Cracks let water reach that base, which softens it, washes it out, and, if you get hard freezes, expands as ice. Each cycle makes the crack wider. Filling cracks while they are narrow is cheap, and it is what keeps a crack from becoming a pothole or a sunken slab.

How to fill cracks yourself

1. Pick a dry day with temperatures comfortably above about 50 degrees, and no rain in the forecast for at least a day. Check the product label for its own limits.
2. Clean the crack. Pull weeds, scrape out loose debris with a screwdriver, and blow or vacuum out the dust. Filler does not stick to dirt.
3. Use backer rod in wider cracks. For cracks deeper than about half an inch, press foam backer rod in first so the filler does not disappear into the crack.
4. Fill slightly below the surface with a filler made for your driveway type: asphalt crack filler for asphalt, and concrete crack sealant for concrete.
5. Let it cure before driving on it, usually a day or more. Follow the product directions.

Sealcoating asphalt

If you have an asphalt driveway, sealcoating every 2 to 3 years protects it from sun, water, and oil. Fill the cracks first, then sealcoat. Sealing too often builds up a layer that can crack and peel, so more is not better. Concrete driveways do not need sealcoat, though some homeowners apply a penetrating concrete sealer, especially where de-icing salt is used.

When cracks mean something bigger

• Spiderweb cracking over a large area of asphalt, sometimes called alligator cracking, means the base underneath has failed. Filling it is a temporary fix.
• Sunken or tilted concrete slabs usually mean soil has washed out or settled underneath. Lifting the slab can fix it if the concrete is intact.
• Cracks along the house where the driveway meets the garage or foundation deserve attention, since water there can reach the foundation. See when to worry about foundation cracks.
• Cracks that reappear right after filling often mean ongoing movement or a drainage problem.

Water is often the root cause. If downspouts empty onto the driveway or the edges, redirect them. See gutter cleaning for getting roof water away from the house.