The barrier to entry in this trade is a trip to the hardware store, which means the gap between the best and worst operator in any town is enormous. Seven questions separate a professional pressure washing company from a person with a machine.
The questions, and the answers you want
1. How will you clean my siding? The only right answer involves soft washing. Anyone planning to put high pressure on vinyl or painted wood should not be allowed near it.
Listen for the mechanism, not the label. A good answer describes applying a diluted solution, letting it dwell, and rinsing at low pressure — and it mentions that the solution kills the growth rather than blasting it off. The distinction between the two methods, and what each one is for, is set out in the comparison of soft washing and pressure washing. If the person you are speaking to cannot explain the difference in a sentence, they do not know it.
2. How will you clean my roof? Same test, higher stakes. Low-pressure chemical treatment is the manufacturer-endorsed method; pressure on shingles takes years off the roof.
The stakes are higher because roof damage is invisible from the ground and permanent. Granules stripped from shingles do not grow back, and they are the layer standing between asphalt and sunlight. Ask what pressure they use on a roof; the answer should be roughly what comes out of a garden hose. Anyone describing a spinning attachment or a wand on shingles is describing a resurfacing, not a cleaning.
3. Are you insured? Ask for the certificate, not the claim. Exterior cleaning involves ladders, water and other people’s property.
A certificate of insurance is a document, and any insured operator can have theirs sent to you without fuss. The reason it matters is the shape of the risk: the expensive failures in this trade are not scratched paint, they are water inside a wall, a broken window, a damaged vehicle or an injury on your property. Vagueness here is the answer.
4. Is the quote flat or hourly? Flat, in writing, before work starts.
Hourly billing pays for slowness, which is the wrong incentive on work you cannot supervise from a ladder. A flat quote moves the efficiency risk onto the operator, where it belongs. It also forces them to look properly at the job before pricing it — which is the whole point. What drives that number up and down is covered in the breakdown of what exterior cleaning actually costs here.
5. What do you do about my plants? The answer should include pre-wetting before solution goes on — that is the step that actually protects landscaping.
Pre-wetting works because saturated foliage cannot take up much more liquid, so anything that drifts onto it is diluted on contact. The full answer includes rinsing again afterwards, and covering or moving anything delicate. Watch for it happening, not just being promised — it takes a few minutes with a hose before the first drop of solution goes anywhere near the wall.
6. Who is actually doing the work? Owner-operated or a crew, either is fine — but you want to know who shows up.
The reason to ask is accountability. If the person quoting is not the person washing, you want to know who is training them and who you speak to when something needs sorting. There is nothing wrong with a crew. There is something wrong with not being able to get a straight answer about it.
7. What happens if I am not happy? A confident operator walks the job with you at the end and fixes anything that is not right before leaving.
The walk at the end is the tell. It costs the operator nothing if the work is good and everything if it is not, which is exactly why the ones doing good work offer it and the ones rushing to the next job do not.
Red flags that end the conversation
A quote given without seeing the property or photos of it. Pressure on roofs or siding presented as normal. No insurance, or vagueness about it. Door-to-door pressure tactics with a today-only price. Any answer to the plant question that amounts to ‘it is fine’.
None of these guarantee a bad job. All of them shift the odds in the wrong direction on work where the damage from a bad job exceeds the cost of a good one.
Two more worth adding to the list
Cash only, no paperwork. There is nothing suspicious about a small operator, but there is about one who will not put a number and a scope in writing.
And an unwillingness to say what will not come out. Every property has something that will not fully clear — a rust stain that has been there for years, an oil patch that has soaked deep into the slab, a deck board too far gone. An operator who promises everything will look new has either not looked or is planning to argue with you later.
How to check the answers without being an expert
You do not have to know the equipment to test whether someone knows what they are doing. Three things do most of the work.
- Ask an open question and listen for mechanism. “What is actually growing on my north wall?” A professional will talk about moisture, shade and colonies. An amateur will talk about dirt.
- Ask what they would not do. Everyone will tell you what they can clean. The useful answer is where they draw the line — what they will not put pressure on, what they will not promise to remove.
- Look at the equipment, not the truck. A surface cleaner rather than a wand for concrete, a low-pressure applicator for walls, hoses long enough to reach without dragging the machine into the beds. Wood surfaces are their own discipline again, and the way a deck gets ruined by too much pressure is a good example of a job where the right answer is deliberately gentler than the customer expects.
Then judge the result at the right moment. Everything looks clean while it is wet. Look at the house the following week, in daylight, from the road and from close up.
What vetting looks like in Southeast Missouri
In a rural market the calculus is a little different from a city one, in ways that mostly work in your favour. Reputation travels here. An operator working out of Patton, Marble Hill or Fredericktown is going to run into their customers at the feed store and the school run, and that is a stronger accountability mechanism than any review site. Asking a neighbour who they used is a genuinely good research method in this region.
The distances change things too. A hundred-mile radius means the person quoting your job in Poplar Bluff or Ste. Genevieve is planning a real drive, so confirm they actually cover you rather than assuming. Seasonal operators who appear in spring and vanish in autumn are more common the further out you go, and the problem with them is not the work — it is that there is nobody to call in October.
There are also regional specifics worth raising directly, because they separate the operators who know the area from the ones who do not. Ask what they do about orange staining from iron-rich well water, which is common on private supplies here and needs different chemistry from anything organic. Ask how they handle the growth on a heavily shaded north wall under mature oak, because that is the standard local condition rather than an edge case. Ask about freeze-thaw damage on older concrete and whether cleaning will make surface spalling more obvious — sometimes it does, and you deserve to know that before rather than after. If the house itself is the job, the specifics of the process are laid out under house washing.
Common questions
Should I be at home while the work is done?
Not necessarily, but it helps at the start and at the end. At the start so windows are shut and anything that needs moving gets moved; at the end for the walk round. The middle is just work.
Is a licence required to pressure wash in Missouri?
There is no state trade licence for exterior cleaning as such, which is precisely why the questions above matter. Requirements can vary by municipality for things like business registration and wash-water handling, so ask locally rather than assume. Insurance is the thing you should insist on regardless.
How much notice should I expect to give?
More in spring than at any other time of year, because the good window is short and everyone wants it at once. An operator who can start tomorrow in May is either very well organised or not very busy, and it is fair to wonder which.
What should I do before the crew arrives?
Close all windows and doors, move vehicles and anything fragile off the surfaces being cleaned, unplug or cover exterior electrics that are not weather-rated, and point out anything you already know is damaged — a loose board, a cracked pane, a leaking window seal. Existing faults found before work starts are information. Found afterwards, they are an argument.
What if something gets damaged?
An insured operator handles it through their insurance, which is the entire reason the certificate matters. Raise it immediately rather than after the truck has gone, and photograph it. This is also the argument for the end-of-job walk: it settles the state of the property while both parties are standing in it.
Are online reviews worth anything in a small market?
Some, but there are fewer of them and they are easier to skew in either direction. Weight them less than a specific recommendation from someone whose property you can go and look at, and less than the answers to the seven questions above.
Ask us all seven. We enjoy the questions — they are the ones that make the cheap-and-fast operators uncomfortable. Read more about a professional pressure washing company →