Fill driveway cracks before winter
Water that sits in a crack freezes, expands and makes it worse. Seal cracks while it's still warm enough for the product to cure.
Step by step
Buy a product made for your surface. Concrete and asphalt need different fillers.
Work only while temperatures stay inside the label's range. Most products need roughly 40–50°F or warmer, a frost-free surface and no rain on the way.
Pull weeds and remove loose material from the crack. Some manufacturers recommend opening narrow cracks to at least ¼ inch with straight sides.
Vacuum or blow out the dust. The crack must be clean, dry and free of oil for the sealant to stick.
For deeper cracks, press in foam backer rod a little wider than the crack so the sealant stays within the depth on the label, often ¼ to ½ inch. Don't puncture the rod.
Fill to the level the label specifies. Pourable fillers may call for a slight overfill. Self-leveling sealants usually sit flush or slightly below the surface so tires don't pull them out.
Don't smooth sealant with water unless the label says you can.
Keep traffic off for the full cure time. Depending on the product, that ranges from under an hour for foot traffic to three days for cars.
Safety first. Cracks wider than the product allows (often ½ inch) need a patching product. Cracks that keep widening, lift or go uneven can mean a base or drainage problem, so have a concrete contractor take a look. Don't use deicers on concrete during its first winter. Use sand for traction, and never use ammonium-based deicers.