Is pressure washing safe for brick, stucco and siding?

Surface by surface

The material decides the method. Any contractor who uses one setting everywhere will eventually damage something.

• Concrete driveways, sidewalks, patios — high pressure with a rotary surface cleaner is correct
• Brick — low pressure only; high PSI blows out mortar joints, especially pre-1970 lime mortar
• Stucco and EIFS — soft wash only; pressure creates pinholes that admit water into the wall
• Vinyl and Hardie siding — soft wash; pressure forces water behind the panels
• Painted wood — soft wash; pressure strips paint and raises the grain
• Asphalt shingles — zero pressure; anything more removes granules and voids warranties

What damage looks like after the fact

Sandy mortar dust at the base of a brick wall, fuzzy raised grain on a fence, pinholes in stucco, wavy or lifted siding panels, granules in the gutters after a roof wash, and stripe marks across a driveway are all signs the wrong tool or the wrong distance was used. Most of it isn't reversible without repair work.

The right questions to ask a washing contractor

Ask what pressure they'll use on your specific surface, what solution they apply, how they protect landscaping, and whether they're insured for property damage. A contractor who answers those four crisply is a contractor who has thought about your house.