Driveway Sealcoating in Oshkosh, WI
A residential driveway in Oshkosh takes two kinds of punishment that have nothing to do with the cars parked on it. The first comes from below: clay subgrade that holds water, a water table that sits close to the surface across the low ground near the lake and the river, and frost that WisDOT measures at 18 inches or more before it will call a road frozen. The second comes from above, in the form of the salt and brine that Winnebago County lays on 689 lane miles of highway and that rides home on your tires every day from December to March. Sealcoating does nothing about the first problem. It does a great deal about the second.
Sealer is a wear layer, not structure. It is a coal tar or asphalt emulsion, loaded with silica sand, brushed or sprayed over asphalt that has been cleaned down to bare pavement. What it buys you is a surface that sheds water instead of absorbing it, resists the chloride brine that drips off a car in a heated garage, and takes UV punishment on behalf of the binder underneath. Asphalt fails when the binder that glues the aggregate together oxidizes and goes brittle. A sealed surface oxidizes far more slowly, which is the entire argument.
The sequence matters more than the product. Cracks get filled first, because sealer bridged over an open crack is sealer that will tear in the first hard freeze. The surface gets cleaned, because sealer over dust is sealer that peels in sheets by August. Oil spots get primed, because nothing sticks to a driveway that has had a leaking transmission parked on it for two years. Then two coats go on, with a third in the turning areas near the apron where tires scrub hardest. Anything less than that sequence is a paint job, and it will look like one within a season.
Signs your driveway is due
Sealcoat wears out quietly. It does not fail in a way that gets your attention, which is why so many Oshkosh driveways go five or six years between coats and then need patching instead. These are the things to look for, ideally in May when the surface has dried out from the thaw.
- The color has gone from black to a flat gray or brown, especially in the wheel tracks
- Individual stones in the surface are visible and feel loose under a thumbnail
- Water beads up in some spots and soaks straight in on others
- Hairline cracks have opened into lines you can lay a pencil in
- The apron end, where county salt gets tracked in first, looks noticeably worse than the garage end
- Rain leaves dark patches that take much longer to dry than the rest of the surface
That last one is the important one in this town. A patch that stays wet after everything else has dried is asphalt that has gone porous, and porous asphalt over lakebed clay is a frost problem waiting for December.
Seal it, patch it, or replace it
Sealcoating is cheap and it is not a repair. Knowing which of these three you actually need saves a lot of money, and the difference is usually visible from the end of the driveway.
Seal it
The surface is intact, cracks are narrow, and the driveway drains. This is the large majority of Oshkosh driveways under 20 years old and it is the cheapest outcome by a wide margin.
Crack fill first, then seal
Cracks have opened past a quarter inch but the pavement is still one piece and still firm underfoot. [Hot rubber crack filling](/crack-filling) goes in first and the sealer goes over the top.
Patch first, then seal
There are soft spots, sunken areas, or webbed alligator cracking in one or two places. Those areas need [asphalt patching](/asphalt-patching) because they are base failures, and sealer over a base failure hides it for about four months.
Replace it
The surface flexes underfoot, alligator cracking covers a third or more of the area, or water ponds and stays. At that point the base has failed and no surface treatment is worth the money.
If you are unsure which category you are in, the flex test settles it. Walk the driveway on a warm afternoon and press hard with your heel in the worst area.
Firm pavement is a sealing job. Pavement that gives is a base problem, and you should read the [old lakebed guide](/old-lakebed-driveway-problem) before spending anything.
Driveway Sealcoating FAQs
How often should an Oshkosh driveway be sealed?
Every two to three years for most homes, and closer to two if the driveway faces south or gets heavy winter salt tracking. Sealing every single year is a common mistake here. Sealer that goes on before the previous coat has worn thin builds up, and thick built-up sealer cracks in its own right when the ground heaves in February. The honest test is to look at the surface in late spring. If the aggregate is showing through and the color has gone gray-brown rather than black, it is time.
My driveway is brand new. When can it be sealed?
Wait. New asphalt needs a minimum of 30 to 60 days to cure before it is sealed, and in this climate most crews will push a driveway paved in September to the following spring rather than seal it late in the year. The light oils in fresh asphalt have to work their way out. Seal too early and you trap them, which leaves a soft surface that scuffs and tracks. A new driveway is at its most durable in its first couple of seasons anyway, so there is no urgency.