Asphalt, sealcoating and concrete
Answers
These are the questions we get asked about driveways and parking lots, answered the way we would answer them on the phone, with what is true in northwestern Wisconsin rather than what is true somewhere warmer.
41 questions, answered in full.
Sealcoating
What sealer is, what a coat of it does, and where it stops being the answer.
Can I sealcoat my own driveway?
Yes, and what decides whether it holds up is not the coat itself but the cracks and the cleaning that happen before it.
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.
How long does it take to sealcoat a driveway?
The work on a normal residential driveway is a few hours, and the part that takes a day or two is the cure that has to follow it.
How many coats of sealer does a driveway need?
Two coats is the normal answer on a driveway, and one coat is enough on a surface that was sealed two or three years ago and has held up.
How much does sealcoating cost?
Sealcoating is priced by the square foot of surface, and Black Widow Sealcoating publishes a rate of $0.15 to $0.25 per square foot.
How often should a driveway be sealed?
Every two to three years in northwestern Wisconsin, because freeze and thaw here does more damage to a driveway than sun does.
Is a freshly sealed driveway slippery?
A sealed driveway is not slippery once the coat has cured, because sand mixed into the sealer is what gives the finished surface its grip.
Is sealcoating worth it?
Sealcoating is worth it while the asphalt under it is still sound, and it is money wasted once the base has failed.
Is sealer sprayed on or squeegeed on?
Both are used, and the difference that matters to you is that a squeegee pushes sealer into the surface while a spray lays it on top.
What is sealcoating?
Sealcoating is a thin coat of asphalt emulsion spread over paved asphalt to keep water, sun and fuel out of the surface underneath it.
When can I drive on a freshly sealed driveway?
Usually 24 hours for a car and 48 before anything heavy, and the number moves with the weather, so the one you are given that day is the one to go by.
Weather and the season
When the work can be done in northwestern Wisconsin, and what a winter does to a surface.
How cold is too cold to sealcoat?
Below 50 degrees is too cold to sealcoat, and the number has to hold overnight as well as during the day for the coat to cure.
What happens if it rains right after sealcoating?
Rain on sealer that has not cured washes it off the surface in streaks, and the affected areas have to be recoated rather than left to dry.
When is sealcoating season in Wisconsin?
Sealcoating season in Wisconsin runs from about May through early October, and it is the overnight low rather than the daytime high that opens and closes it.
Why do potholes form?
A pothole is what is left after water gets under the asphalt, freezes and lifts it, and traffic breaks the unsupported piece out.
Why does a parking lot heave in the spring?
Water in the ground under a lot freezes into layers of ice that lift the pavement, and the lot drops unevenly when those layers melt in spring.
Why does asphalt crack over the winter?
Water gets into the asphalt, freezes, expands about nine percent, and levers the sides of every opening a little further apart, dozens of times a winter.
Reading the damage
What the cracks, the gray, the loose stones and the low spot are telling you.
How do I get oil stains off my driveway?
Oil stains have to be scrubbed out with a degreaser and rinsed before any sealer goes down, because nothing bonds over oil.
How do I know if my driveway needs replacing instead of sealing?
A driveway needs replacing once the base has failed under roughly a quarter to a third of the surface, because past that you are patching patches.
What causes a dip in a parking lot?
A dip means material under the pavement has gone somewhere, usually a settled utility trench, a failing drain structure, or water washing the base out.
What is alligator cracking?
Alligator cracking is asphalt broken into a pattern of small connected squares, and it means the base underneath that area has already failed.
Why are there loose stones all over my driveway?
Loose stones coming off the surface is called raveling, and it means the binder holding the top of the asphalt together has worn out.
Why does the edge of my driveway crumble?
Driveway edges crumble because there is nothing beside them holding the asphalt up, so anything that drives onto the edge breaks a piece off.
Why does water stand in one spot on my parking lot?
Water stands where the surface has settled below the grade around it, which means the base under that spot moved or a drain near it stopped working.
Why is my asphalt turning gray?
Asphalt turns gray because sun and oxygen have burned the binder out of the top of the surface, leaving the stone in it exposed.
Repair, overlay and repaving
When a surface is worth keeping, and what replacing one involves.
Asphalt or concrete for a parking lot?
Asphalt costs less to build and needs a maintenance cycle to reach its life, and concrete costs more up front and asks for little until it fails.
How thick should an asphalt parking lot be?
The section a lot needs is set by the soil, the traffic and the frost depth, and on anything of size it is an engineer's number rather than a rule of thumb.
Should I sealcoat or resurface my driveway?
Sealcoat while the surface underneath is still sound, and resurface once the asphalt itself has worn or cracked past what a coating can protect.
What is a mill and overlay?
A mill and overlay grinds off the top layer of an asphalt surface and lays new asphalt in its place, so the lot gets a new surface without getting any taller.
What is the difference between resurfacing and repaving?
Resurfacing puts a new layer of asphalt over the old one and keeps the base, while repaving takes the old surface out and rebuilds what is underneath it.
Parking lots
Layout, stall sizes, thickness, cycles and the words on a bid.
How often should a commercial parking lot be sealcoated?
A commercial lot in northwestern Wisconsin is normally sealcoated every two to three years, and the drive lanes come up before the stalls do.
What is a pavement condition index?
A pavement condition index is a score from 0 to 100 that rates a paved surface from the distresses visible on it, following ASTM D6433.
What is a standard parking stall size?
There is no single standard: the zoning code where your property sits sets the stall and aisle minimums, and they differ between neighboring towns.
What should be on a parking lot bid?
A parking lot bid should give the area, the work in the order it happens, the material by name, and how long the lot is out of service.
Concrete
Driveways, sidewalks, salt damage and how thick a slab has to be.
Does road salt damage concrete?
Salt does not attack concrete chemically, but it makes the surface freeze and thaw far more often than it otherwise would, and that is what flakes the top off.
How thick should a concrete driveway be?
Four inches over a properly compacted base is the usual thickness for a driveway carrying cars, and the base under it decides more than the inches do.
When does a sidewalk need replacing?
A sidewalk is due once a panel has lifted, dropped or broken enough to catch a foot, and how much is too much is set by your city or county.
Why does new concrete crack?
Concrete shrinks as it cures and it has no give, so it cracks somewhere, and the job of the saw cuts in a new slab is to decide where.
Winter
Ice melt, plows, and what both of them do to what is underneath.
Which ice melt does the least damage to asphalt and concrete?
Ice melt damages pavement through the meltwater it makes rather than chemically, so the less of it that clears the ice, the less the surface takes.
Getting a quote
How to measure the job, and what to ask before anybody starts.
How do I measure my driveway for a sealcoating quote?
Measure the length and the width in feet and multiply them, and break an odd shaped drive into rectangles and add them up.
What should I ask a sealcoating contractor?
Ask what the sealer is by name, what happens to the cracks first, how long you stay off it, and what insurance is in place.
Send a photo of the worst spot
Free estimates across northwestern Wisconsin. Tell us what you are looking at and we will tell you what it is, including when the answer is that it can wait a season.