Sealcoating
Does my driveway need crack filling or sealcoating?
It usually needs both, in that order: the cracks get filled first because sealer cannot bridge an opening, and the coat goes over the top afterward.
The numbers
- Crack filling is priced by the linear foot of crack. Sealcoating is priced by the square foot of surface.
- Hot rubber goes in at around 400 degrees so it bonds to both walls of the crack.
- Sealer dries to a film. It cannot span a gap of any width.
- Cracks wide enough to take a finger, or cracking broken into squares, are usually a repair rather than a fill.
Why the cracks come first
Sealer is a thin wear layer. Poured over an open crack it sags into it, dries, and splits along the same line as soon as the crack moves, which in northwestern Wisconsin is the first cold night. The crack is back inside a month and the coat over it was wasted.
Filled first, the crack is a solid rubber joint that moves with the asphalt. The coat then goes over a continuous surface and does the job it is good at.
When it is crack filling on its own
A drive with a handful of cracks and a surface that is still black does not need sealing yet. Filling the cracks is what shields the base, which is the expensive failure, and the sealing waits for its own cycle.
That is a smaller job than most people expect, because it is measured along the cracks rather than across the drive.
When it is neither
Once cracking has broken into a network of squares, or an area gives under your foot, the base under that area has failed. Filling and sealing both go over the top of a problem that is underneath. Those areas get cut out full depth and rebuilt, and the rest of the drive can still be filled and sealed the same day.