Most homeowners can safely pressure wash a driveway, walkway or plastic patio furniture with a consumer machine, a wide-angle nozzle and a surface cleaner attachment, as long as they start at a distance and respect the machine's power. Stucco, roofs, windows, screens and anything high off the ground are where do-it-yourself jobs go wrong. The difference between a good weekend project and an expensive repair is mostly nozzle choice, distance and knowing what to leave alone.
Choosing a machine
Pressure is measured in pounds per square inch (PSI) and flow in gallons per minute (GPM). Cleaning power is a combination of the two, so a higher PSI machine is not automatically better.
| Type | Typical output | Good for | Cautions |
|---|---|---|---|
| Electric, light duty | About 1,300 to 2,000 PSI, 1.2 to 1.6 GPM | Patio furniture, cars, small decks, light cleaning | Slow on large concrete; needs a GFCI outlet |
| Electric, heavy duty | About 2,000 to 2,800 PSI | Driveways, walkways, fences with a surface cleaner | Check circuit capacity; cord and hose management |
| Gas-powered | About 2,500 to 4,000 PSI, 2 to 4 GPM | Large concrete areas, tough stains | Can damage surfaces fast; exhaust fumes; noise |
| Rental commercial unit | 3,000 PSI and up | Big slabs and grime | Easy to cause damage; read instructions carefully |
Machine specifications vary by brand, so treat the ranges as typical, not guaranteed. Make sure your outdoor spigot can supply the flow the machine needs, or it will run dry and may be damaged. Gas-powered units must never be run in a garage or enclosed space because of carbon monoxide.
Nozzles, plain and simple
Nozzles are color-coded by the angle of the spray fan. Wider angles mean less force on the surface.
- 0 degrees (red): A pinpoint jet that can cut skin, strip paint and gouge concrete. Do not use it for cleaning.
- 15 degrees (yellow): A narrow fan for tough stains on hard concrete, used from a distance.
- 25 degrees (green): The general-purpose choice for many surfaces.
- 40 degrees (white): A gentle, wide fan for delicate surfaces and rinsing.
- Soap nozzle (black): Low pressure for applying detergent.
A rotary surface cleaner attachment is worth buying or renting for flat surfaces. It spins a pair of jets under a hood to prevent stripes and spray-back, and it speeds work considerably. The driveway guide shows how to combine it with stain treatments.
What not to pressure wash
- Roofs. Pressure damages shingles and tile, and falls are a serious hazard. See the roof guide.
- Painted stucco and aging paint. It can peel or pit, and water can be forced into cracks. A low-pressure wash is better.
- Windows, door seals and vents. Water can get behind frames and weatherstripping.
- Screens and lanai enclosures. Mesh tears easily and frames bend.
- Electrical equipment. Meters, outdoor outlets, light fixtures and air conditioner coils should not be sprayed directly.
- Soft wood, old mortar and loose pavers. They erode or shift.
The comparison of soft washing and pressure washing explains which surfaces belong to which method.
Safety that matters
- Treat the jet as a cutting tool. High-pressure water can penetrate skin, and injection injuries can look minor while causing serious internal damage. Seek medical attention immediately after any skin contact with the jet. Never point the wand at yourself or anyone else.
- Wear protection. Closed shoes with grip, long pants, safety glasses and hearing protection. Gloves help with chemicals.
- Use a GFCI outlet for electric machines, and keep connections off wet ground.
- Mind kickback. The trigger gun pushes back, particularly with strong machines. Keep a firm stance, and do not work from a ladder.
- Never mix chemicals. Bleach with ammonia or acid-based cleaners releases toxic gas. Use one product at a time, and rinse between products.
- Watch the heat and sky. South Florida afternoons are hot, and storms build quickly. Work early, drink water, and stop when you hear thunder.
A sensible sequence
- Sweep, move furniture, close windows and cover outdoor outlets.
- Wet nearby plants.
- Test the nozzle in a hidden spot, starting a couple of feet away and moving closer only if needed.
- Apply detergent with the soap nozzle if the surface needs it. Let it dwell without drying.
- Work from top to bottom and overlap each pass slightly.
- Rinse everything, including surfaces that only caught spray, then let the area dry fully.
Water use and runoff
Miami-Dade's year-round water restrictions apply to landscape irrigation, and the county's page lists pressure cleaning of paved surfaces among exempt activities. Even so, wash water is not harmless. Keep soapy water out of storm drains, point runoff at your lawn, and avoid sending bleach or oily water into the street. The runoff page explains why. Low-volume equipment uses less water and is easier to control than a bare wand on a garden hose.
Do it yourself or hire out?
If the job is flat concrete and you have a free morning, doing it yourself is reasonable. If it involves height, a delicate finish or large areas, a professional with the right equipment is often cheaper than repairing a mistake. Getting one written quote before you start is a cheap way to find out which side of that line your job falls on.
Frequently Asked Questions
What PSI do I need to clean a driveway?
Many homeowners use machines in the range of about 2,000 to 3,000 PSI with a surface cleaner. Flow rate and attachments matter as much as the number.
Can I use bleach in my pressure washer?
Many machines have a detergent tank not designed for bleach. Check the manual, and consider applying bleach solutions with a separate sprayer. Protect plants and never mix chemicals.
Why does my concrete have stripes?
Uneven movement or distance with a narrow nozzle. A surface cleaner attachment prevents it, and another pass can blend light lines.
Is it okay to pressure wash in the rain?
Light rain is not a safety problem, but lightning is. Chemicals also need dry weather to work well. Work early on days with afternoon storms.
What should I do if the jet touches my skin?
Get medical attention right away, even if the wound looks small. Injection injuries can be deceptive.