The Homeowner’s Guide to Pressure Washing

“Pressure washing” has become the catch-all term for exterior cleaning, but it describes only one of two distinct methods. True pressure washing relies on mechanical force — water alone, at high PSI — to physically blast grime off a hard surface. It is the right call for concrete, pavers, and stone, which can take that force without damage.

Soft washing does the opposite: a cleaning solution, usually a mild bleach- or biodegradable-based mix, does the actual cleaning chemically, and the rinse afterward happens at low pressure — often no more than a garden hose would deliver. It is the only appropriate method for roofs, siding, stucco, and most painted or wood surfaces, because those materials are not built to withstand direct high-pressure force.

High pressure aimed at a shingle roof strips the protective granules right off, shortening the roof’s life and frequently voiding the manufacturer’s warranty outright. Aimed at siding, it can force water behind panels and into wall cavities, where it causes rot and mold that will not show up until months later. Aimed at old mortar or soft wood, it can gouge and etch a surface permanently in seconds.

This is the actual source of almost every pressure-washing horror story — not the concept of exterior cleaning itself, but a crew using one pressure setting on every surface because it is faster than switching equipment and technique mid-job.

Concrete driveways and walkways typically hold up well on an annual cleaning, or ahead of a specific event, in a desert climate. Siding and stucco generally need a soft wash every one to two years, faster in shaded, north-facing areas where algae holds moisture longer. Roofs showing the first signs of black streaking are usually good for two to three years between soft washes once properly treated. Gutters need clearing at least twice a year in most desert climates — once in spring, once after monsoon season moves through.

• Driveways & walkways — annually, or before a listing or event
• Siding & stucco — every 1–2 years
• Roofs (soft wash only) — every 2–3 years once treated
• Gutters — twice yearly, spring and post-monsoon

A complete quote should specify which method will be used on which surface, not just a flat per-square-foot number. Ask directly whether the company soft washes roofs and siding, or whether they run one machine at one pressure for the whole property — the answer tells you almost everything you need to know before they arrive.

Be cautious of a quote dramatically below every other estimate you have gathered. The gap is usually one of three things: a faster, harsher pressure setting than the surface should get, a skipped pre-treatment step that leaves stains behind, or a company without liability coverage pricing around the cost of carrying it.

A few minutes of prep make any wash more effective and protect what should not get wet. Move patio furniture, potted plants, and anything stored against the house away from the wash area. Close windows and vents on the elevation being cleaned, and confirm gate or side-yard access in advance if nobody will be home.

• Clear the wash area of furniture, planters, and loose items
• Close windows and any exterior vents near the work area
• Confirm gate codes or side-yard access ahead of time
• Note any known soft spots, loose trim, or prior repairs before the crew arrives