Before you hire a pressure washing company: the questions that sort pros from sprayers

Ten minutes of questions that protect the house

Before you hire a pressure washing company, ask how they will clean each surface and at what pressure, whether they carry insurance including workers' compensation, how they protect plants, pets and windows, what the quote includes, and what happens if the result is not right. A company that answers those clearly, without being prompted twice, is usually the one that runs a careful job. Vague answers about pressure and chemicals are the biggest warning sign.

At Park Cities Power Wash we have been cleaning house exteriors since 2016, and a steady share of our calls come after someone else's visit: stone that is still stained, paint that peeled, mortar that washed out of the joints. Almost all of it could have been avoided with a short phone conversation before the crew showed up. Here are the questions I would ask if I were hiring someone to clean my own house.

Start with method: how will you clean my walls and roof?

This is the question that separates exterior cleaning companies from people who own a pressure washer. A good answer names the surface and the method together. Porous Austin stone, limestone, cast stone and stucco should get a soft wash: low pressure, a cleaning solution that kills the growth, a dwell time, and a gentle rinse. Concrete driveways and sidewalks can take more pressure, ideally with a flat surface cleaner for even results.

Our soft washing article notes that rented gas pressure washers often run 2,800 to 3,400 PSI, far above what stone, stucco, painted siding or shingles can tolerate. If a company tells you they will simply turn the pressure down on your stone, ask what solution they use and how long it sits. Pressure alone removes the visible layer and leaves the roots, so the growth comes back faster and the surface pays for it.

Older homes deserve a follow-up question. Many older houses in Highland Park and University Park have soft mortar, cast stone details, custom paint colors or dark siding that react differently to cleaning solution. Ask whether the company tests a small hidden area first when there is any doubt. Our house washing page describes adjusting the solution for custom paint or dark siding and running a test first, and skipping the chemical step entirely if a paint is not compatible. A company that has never thought about this has probably never cleaned a house like yours.

• Good sign: they ask what your exterior is made of before quoting.
• Good sign: they explain soft washing for stone, stucco, painted siding and roofs.
• Good sign: they mention adjusting solution strength and dwell time by surface.
• Warning sign: one machine, one pressure, every surface.
• Warning sign: they plan to walk on a tile, slate or metal roof.

Ask about the solution, and what keeps it off your plants

Most professional soft washing uses diluted sodium hypochlorite with a surfactant that helps it cling to the wall. That chemistry works, and it will also stress a flower bed if nobody manages it. So ask exactly what happens to your landscaping before, during and after the wash.

On our house washing page we describe pre-wetting plants, covering them, and treating them with a neutralizer afterward, plus covering doorbells, cameras and exterior outlets. You do not need a company to use our exact routine, but you should hear a specific plan rather than "we're careful." Ask, too, whether they want pets and children kept indoors during the work. The right answer is yes.

Insurance is a question, and proof is the answer

Exterior cleaning involves ladders, roofs, wet surfaces and chemicals around someone else's property. If a technician falls from your roofline or a crew damages a window, you want that to be the company's insurance problem, not yours. Ask whether the company carries general liability and workers' compensation for its crew, and ask for the certificate.

Our soft washing article lists confirming full insurance, including workers' compensation, as the first item on its hiring checklist, and we state on our homepage that our team is insured and covered by workers' comp. A company that hesitates or says the crew is "covered somehow" has told you what you need to know.

Read the quote before you compare prices

Two quotes can look similar and describe completely different jobs. Before you compare totals, make sure each one tells you the scope, the method and what is included. Ask whether water, labor and cleaning solution are part of the price, whether a second pass on heavy growth is included, and whether oxidation or rust spots are extra.

I break down what moves a house wash price in what a house wash costs and what moves the price. The short version is that size, surface, condition and access drive the number, and a quote that ignores any of them is either padded or about to change on the day.

• Which surfaces are included, side by side: walls, roof, gutters, windows, flatwork.
• Which method is used on each surface.
• Whether water, labor and solution are included.
• What happens if stains remain after the first pass.
• Whether payment is due on completion, and how you receive the invoice.

Red flags I would walk away from

Some warnings show up before anyone touches the house. Our soft washing article advises caution with cash-only demands, full payment up front, no verifiable address, and bids far below everyone else. I would add a few from the calls we get afterward.

Be careful with anyone who knocks on the door with a machine already on the truck and a price good for today only. Be careful with a company that cannot show you before-and-after photos on surfaces like yours, especially stone or stucco. And be careful with anyone who promises that every stain will disappear before seeing it. Some old oil marks and long-standing rust can only be lightened, and an honest company says so up front.

• Cash only, or full payment before work starts.
• No physical address and no way to check reviews.
• A same-day price from a door knock.
• No photos of similar homes or surfaces.
• Guarantees that every stain will vanish, sight unseen.

Who will actually be standing in your yard?

The person who sells the job is not always the person who does it. Ask whether the crew is the company's own staff or subcontracted day labor, whether technicians are trained on soft washing, and whether you will know who is coming. Our homepage describes a full-time team and uniformed technicians, and we text when the technician is on the way so you are never guessing who is at the gate.

This matters for more than courtesy. A trained technician notices a leaky window, a loose downspout or a cracked tile before spraying near it, and tells you. Someone hired for the afternoon is less likely to stop and ask. If the company cannot tell you who will be on your property, assume it does not know either.

Ask what wash day looks like, minute by minute

A professional company can tell you exactly how the visit will run: when they will confirm, how you will know the technician is on the way, whether someone walks the property with you first, how long the work usually takes and what you need to do beforehand. Our homepage FAQ says most jobs take a few hours, depending on scope and surface size.

If the answer is "we'll show up sometime that week," expect the rest of the job to be just as loose. I walk through a typical visit, including the prep list we send, in how to prepare for house washing day.

What happens if something is missed?

Even careful crews occasionally miss a corner under an eave or a patch behind a shrub, and stains sometimes show up more clearly once the wall dries. What matters is what the company does next. Ask whether they have a written satisfaction policy, how quickly they come back and whether rework costs anything.

Our homepage states a 100 percent satisfaction guarantee and a return within 24 hours if a customer is unhappy, and our house washing page notes that missed spots are fixed at no charge. Whatever company you choose, get the policy in writing or in an email before the job, not after a problem.

It is also fair to ask how the company handles damage, however unlikely. Who do you call, how fast do they respond, and does their insurance cover it? A company that has a clear answer has usually thought about prevention just as carefully, and that is the company you want on a ladder next to your windows.

When you have the answers, choose like this

Lay your notes side by side. The company you want explained its method by surface, described a specific plant and pet routine, showed proof of insurance, gave you a quote that lists what is included, and put its satisfaction policy in writing. Price comes after those, not before. If two companies tie on everything else, take the one that communicated more clearly, because that is a good preview of how the job will go.

If you are still weighing whether to try it yourself first, read what you can safely pressure wash yourself and where to stop before you rent a machine. And if your main concern is dark algae on stone, the whole process is laid out in what is growing on green and black stone and how to remove it. We serve homes within about 30 miles of Dallas, and we are glad to answer every question on this page before you decide.

Questions people ask me