A commercial lot gets dirty in ways a broom does not fix. Tire rubber worn into the turning points, algae on the shaded edge, the black film that builds along a curb line, and oil under wherever vehicles sit longest.
Most of the time we are cleaning because something else is going on afterwards. Paint and sealer are coatings, and a coating is only as good as its bond to the surface underneath, so the wash is what decides whether the work above it lasts.
Asphalt takes much less pressure than concrete does. Too much strips the binder out from between the stones and leaves a rough, pale patch that does not come back, so the work is done with the right chemical and enough dwell time rather than by turning the machine up.
On a striping company’s site, surface cleaning is mostly a story about adhesion. Paint and sealer are coatings, and a coating only lasts as long as its bond to whatever is underneath it. Almost every line that peels off a lot in sheets a few months after it was painted came off something that was never properly clean.
Cleaning as preparation, not as a finish
There is a version of this service that is about appearance, and it is real enough. A grey lot with black streaks down the drive lane looks neglected whatever condition the asphalt is in, and the entrance is the first thing a tenant’s customers see. But the cleaning that actually changes the outcome of a job is the cleaning that happens before something else goes down.
Blowers and brooms handle loose grit, and on most re-stripes that is enough. Washing earns its place where contamination has bonded to the surface rather than sitting on it. Tire rubber worn into a turning point. Algae and mildew on a shaded north edge. The black film that builds along a curb line where dirt compacts and never dries out. Those do not blow off, and paint over them is paint on a release layer.
Oil, and why it is a different problem
Petroleum dissolves the bitumen that holds asphalt together, so a spot that has been dripped on for a year is not merely dirty, it is softened. Pressure alone drives the oil deeper rather than lifting it out. What works is a degreaser given time to sit and pull the contamination back to the surface, then rinsing, and on stubborn areas heat, because hot water moves grease that cold water pushes around.
Even then some spots do not come fully clean, and that is worth saying before the work rather than after. Where sealer is going down afterwards, a stubborn spot gets treated with an oil spot primer so the coating has something to hold. Where paint is going down, a stall line is usually moved a few inches rather than run through a patch that will not hold it.
Pressure is not the setting that matters most
Asphalt tolerates far less pressure than people expect. Turn it up and the water starts stripping binder out from between the stones, leaving a lightened, rough patch with the aggregate standing proud. That damage is permanent, it is very obvious once the lot dries, and it happens fastest exactly where somebody is trying hardest, on the stain that will not shift.
What does the work is a combination of the right chemical, enough dwell time for it to act, water hot enough to help, and a surface cleaner rather than a wand. A wand concentrates everything into a narrow fan that a careless operator holds too close and too long, which is what produces the striped, etched look on a badly washed lot. A rotating surface cleaner spreads the same energy across a wide head at a fixed height and leaves an even result.
Concrete is a different substrate and takes more. Sidewalks, dumpster pads, loading aprons and entrance walkways are usually the areas that respond best, which is why a wash quote for a commercial property often covers more concrete than asphalt.
What has to be settled before a crew turns up
Three practical things decide whether a wash day runs smoothly, and none of them is about the equipment.
Water. A commercial lot uses a lot of it, so somebody has to confirm there is a working spigot on the property and that the crew is allowed to use it, or the water gets brought in and that changes the quote.
Drainage. Where the runoff goes matters, and it is a question for the property rather than an assumption. Some sites drain to landscaping, some to a storm inlet, some to a sanitary connection at a wash pad. Settle it with the property manager in advance rather than discovering it with a hose already running.
Access and timing. Cleaning is wetter and slower to clear than striping, and a washed area stays wet long after the crew has moved on. Surfaces that are being coated afterwards have to dry fully before anything goes down, which is what usually turns a wash and seal into a two-visit job.
| Settle in advance | The question | Why it changes the job |
|---|---|---|
| Water | Is there a working spigot on the property, and is the crew allowed to use it? | If not, water gets brought in — and that changes the quote |
| Drainage | Where does the runoff actually go — landscaping, a storm inlet, or a sanitary connection? | A question for the property, not an assumption to discover with a hose already running |
| Access and timing | How long can the area stay wet, and what happens on it next? | Surfaces being coated afterwards must dry fully first — usually what turns a wash-and-seal into a two-visit job |
Where it fits in the order of work
Cleaning comes first, always. After that the sequence is the one every other job on this site runs to: fill the cracks, seal the surface, let it cure, then stripe. Washing a lot after it has been striped is fine as maintenance, though it wants a lighter touch, because the same pressure that lifts a stain will lift a line.
The one case where washing changes the plan rather than fitting into it is a lot somebody is about to seal that has never been cleaned properly. A sealer coat over an unwashed surface is money spent on a coating that is going to release, and that is a conversation worth having before the drums arrive rather than a year later.
What a badly washed surface looks like afterwards
- Light etched bands across the asphalt, wider at one end, which is a wand held too close and swung in an arc
- Exposed aggregate standing proud in patches, where binder has been stripped out by too much pressure
- A clean strip down the middle of a drive lane and a dirty margin either side, meaning nobody overlapped the passes
- Streaks that reappear as the surface dries, so the contamination was pushed around rather than lifted
- Oil spots that look clean wet and reappear dry
- Debris and silt left in the gutter line or over a storm inlet after the crew has gone
Reading a surface cleaning quote
- Square footage, and whether asphalt and concrete are priced separately, because they are different work
- Hot water or cold, and whether a degreaser is included or charged as an extra
- Surface cleaner or wand for the open areas
- Oil spots called out individually, with an honest statement of which ones may not come fully clean
- Who supplies the water, and what happens if there is no usable spigot
- What happens to the runoff and to the debris the wash leaves behind
- If a coating is going on afterwards, how long the surface has to dry first and whether that is a second visit
Questions worth asking before booking
- Does this lot actually need washing, or would blowing and sweeping do the same job for the work we are planning?
- Which stains do you expect to shift, and which are you telling me now will not come out?
- What pressure are you working at on asphalt, and how do you keep from etching it?
- Where does the wash water go on this property, and is that arrangement agreed with whoever manages the site?
- If we are sealing afterwards, how long between the wash and the sealer?
- Are the accessible spaces getting cleaned too? Faded hatching under a layer of grime reads as worn out when it may only be dirty, and that is worth knowing before a compliance re-mark gets quoted
The useful answer to the first question is often no. A contractor who tells you the lot does not need washing before a re-stripe is telling you something about how they price the rest of the work too.