Can you get the grease out of the drive-thru lane?

We reduce it, and we start dry — that order comes out of the federal industrial stormwater permit, and we work to it either way. Grease still sitting on the surface comes up with absorbents and sweeping before water touches it. What has soaked into the concrete is a different matter: PCA warns that solvent degreasers can dissolve oil and carry it deeper into the pores. So the honest expectation is an improvement, not a slab that looks like it was never a drive-thru.

Do you have to close the whole lot?

Not necessarily: a lot can be worked in sections, with only the section being washed empty of cars. Tell us the order that costs your tenants least, and the hours the lot is quietest. If the lot never really empties — a hotel, a clinic, a store that runs around the clock — say so at the estimate.

Do you use biodegradable products?

The product depends on the surface and on where the water ends up, so ask what is going on your pavement. The word biodegradable is not an answer to that. A Florida county stormwater programme says directly that biodegradable does not mean non-toxic and that none of these products are harmless to aquatic life. The label describes how a molecule breaks down over time. It says nothing about what the water does on its way to the drain.

Will the pressure damage the concrete?

There is no published safe pressure for concrete, and a contractor quoting you one is quoting a number no standards body stands behind. NRMCA's position is that curing decides how hard a surface ends up, so two slabs of the same age can behave differently under the same machine — and NRMCA lists a high-pressure washer as a tool for removing unsound surface concrete, which is exactly what a weak slab has. So the slab's condition matters before the machine is set, and where the top of one is already going, the estimate says so.

Parking lot cleaning

Part of a parking lot job happens before the washing starts. Oil and grease come up with dry methods first, before any water touches the slab — that is the order EPA sets in its industrial stormwater permit for the sites that permit covers, and it is how we work on every lot either way, because rinsing grease is how it leaves your property and ends up somewhere it is not allowed to be. And some of what you are pointing at is not a stain at all — an acid spill takes concrete away, and nothing puts it back.

The dry work comes before the water

On a lot, the first part of the job has no water in it. EPA's industrial stormwater permit sets that order for the sites it covers — dry pickup of oil and grease before any water touches the slab, by sweeping, absorbents and hydrophobic mops, together with controls that keep the amount of solids you move to a minimum — and it is how we work on every lot, whether or not your property is one of them. So hot degreaser down the drive-thru lane, then a rinse toward the inlet, is not a faster way of doing the work. It is the exact thing that order exists to prevent. In practice it means a dry pass first: sand and trash out of the corners and the curb line, and the grease at the dumpster pad and the delivery bay lifted rather than pushed. Gum is a separate question: we found no trade body's method for it, so nothing is promised about it here. Tell us if the lot has it. The machine comes out after that. The walkways in front of the units, the walls behind them and the storefront glass each have their own page and their own rulebook; this one is about the pavement.

What the word biodegradable on the drum does not mean

It carries less than it sounds like it does. A Florida county stormwater programme states it without hedging: biodegradable does not mean non-toxic, and none of these products are harmless to aquatic life. The word describes what eventually happens to a molecule. It says nothing about what that molecule does to a retention pond on the way there, which is the only question that matters on a commercial site. Federal law draws its line in a different place again — the industrial stormwater permit authorises pavement and building wash water only where no detergents or hazardous cleaning products are used, and it names bleach as one of them — and the commercial pressure washing page works that argument through rather than repeating it here. On a lot it comes down to one sentence: sodium hypochlorite is a chemistry for the dark biological film on a shaded slab and for a mildewed dumpster enclosure, so what is in the water on your property is never a hypothetical question. So the answer to what do you use is not one comforting word. It is the product, the surface it is going on, and where the water is going afterwards, decided with you and before the day. This site does not print safe for pets and plants either, for the same reason: the document behind that sentence has not turned up. If a bidder's whole answer is biodegradable, the second question is the useful one: where does it end up?

Some of it is not a stain — it is missing concrete

A property manager points at a pale, rough, slightly sunken patch under a delivery bay and asks what it takes to clean it off. The answer can be that there is nothing on it to clean. Acid spills do not deposit a mark, they dissolve the cement paste that holds the slab together: the Portland Cement Association rates a 10% sulfuric acid solution as causing rapid disintegration of concrete, and describes deterioration as increasing once acid pH drops below about 6.5. What you are looking at is where the concrete used to be. No wash restores it. The same mechanism is why acid-washing a tired lot to brighten it is a poor trade. NRMCA warns that chemical treatment may significantly alter the colour of concrete surfaces and may aggravate the situation, and PCA states flatly that acid treatment is not recommended. Old oil is a milder version of the same honesty: once it is down in the pores, cleaning reduces it rather than removes it, and PCA warns that solvent degreasers can dissolve the oil and carry it deeper. Lot concrete also raises the same surface-soundness question as any other slab — how it was cured decides how hard its top is — and the driveway page works through that rather than repeating it here. What we do is tell you at the estimate which marks will move and which will not.

The short list of what we do not do

Part of this job is knowing where our work stops, and that belongs in the first conversation rather than the second month. Where wash water is allowed to go in Florida is a question with a legal answer, and the commercial pressure washing page works through it properly. What it means on a lot is a few questions worth answering before the quote, and they are boring and specific. Where is water meant to go on this site. Who at your management company owns that answer. What has been done here before. And the part that costs us work, said plainly: we are not set up to collect wash water and haul it away, so if that is what your site requires, it needs a contractor equipped for it and we would rather tell you at the estimate than wash it and hope. We do not resurface, seal or re-stripe either. Cleaning changes what is on the pavement; it does not change the condition of the pavement, and a lot that is coming apart needs a paving contractor rather than a bigger machine. Paint is a limit of the same kind: those markings are a coating somebody else applied on a day we know nothing about, so tell us when the lot was last striped. It is a short list.

Common questions

Can you get the grease out of the drive-thru lane?: We reduce it, and we start dry — that order comes out of the federal industrial stormwater permit, and we work to it either way. Grease still sitting on the surface comes up with absorbents and sweeping before water touches it. What has soaked into the concrete is a different matter: PCA warns that solvent degreasers can dissolve oil and carry it deeper into the pores. So the honest expectation is an improvement, not a slab that looks like it was never a drive-thru.
Do you have to close the whole lot?: Not necessarily: a lot can be worked in sections, with only the section being washed empty of cars. Tell us the order that costs your tenants least, and the hours the lot is quietest. If the lot never really empties — a hotel, a clinic, a store that runs around the clock — say so at the estimate.
Do you use biodegradable products?: The product depends on the surface and on where the water ends up, so ask what is going on your pavement. The word biodegradable is not an answer to that. A Florida county stormwater programme says directly that biodegradable does not mean non-toxic and that none of these products are harmless to aquatic life. The label describes how a molecule breaks down over time. It says nothing about what the water does on its way to the drain.
Will the pressure damage the concrete?: There is no published safe pressure for concrete, and a contractor quoting you one is quoting a number no standards body stands behind. NRMCA's position is that curing decides how hard a surface ends up, so two slabs of the same age can behave differently under the same machine — and NRMCA lists a high-pressure washer as a tool for removing unsound surface concrete, which is exactly what a weak slab has. So the slab's condition matters before the machine is set, and where the top of one is already going, the estimate says so.

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