Pressure washing comparisons

Pressure vs soft washing. The deciding question is whether the surface can take force. Concrete can. Asphalt shingles cannot — ARMA is unambiguous about that. Wood cannot take much: Today's Homeowner suggests 1,200 to 1,500 PSI for cedar and calls anything above 2,000 PSI excessive for wood, warning of splintering, etching and stripped fibers. Vinyl siding is a maybe with conditions — guidance from the Polymeric Exteriors Association (formerly the Vinyl Siding Institute) says a power washer can be used but with caution, that some manufacturers do not recommend it at all while others limit PSI and cleaners, and that you should never aim the stream upward because it can force water behind the panels.

Hot vs cold water. Heated water helps with grease and oil. Fixr prices fence power washing (heated) at $0.35 to $0.45 per square foot against $0.30 to $0.40 for cold pressure washing, and notes heat can cause minor damage to older wooden fences. On delicate substrates the heat is a liability, not a feature.

DIY vs professional. Consumer machines are perfectly capable of destroying siding, etching stone and stripping paint — the limiting factor is judgment, not equipment. Fixr puts professional rates at $50 to $150 per hour with most house jobs at two to four hours. If the job involves a ladder, a roof, or chemistry, the professional case is strong. Cleaning solutions used in soft washing are genuinely hazardous: Today's Homeowner warns they can cause second- to third-degree burns and calls for gloves, eye protection, long sleeves and rubber boots.

Whole-house wash vs spot cleaning. Spot cleaning is cheaper but often looks worse, because a clean patch highlights how dirty everything else is. If organic growth is general, wash the whole elevation.

One comparison with a clear winner: on any surface you're unsure about, the lowest effective pressure wins. NPS guidance on masonry puts it well — water at too high a pressure is very abrasive and can easily etch marble, other soft stones and some types of brick, and grains of stone or sand appearing in the runoff mean the pressure is too high.

How to choose

Default to soft washing on anything organic or fragile

Roofs, wood, painted surfaces and most siding. Chemistry kills algae and mildew; pressure just blasts the surface off with it.

Reserve high pressure for sound concrete

Fixr's recommended PSI range tops out around 3,500 for concrete and drops to around 500 for brick. Match the tool to the substrate.

Ask for hot water only where grease is the problem

It's an upcharge, and Fixr notes heat can cause minor damage to older wooden fences. It's not a general-purpose upgrade.

Test in an inconspicuous spot

Whoever does the work — you or a contractor — should start low, in a hidden area, and step up only if needed.

Don't DIY the roof

It combines a ladder, a slippery surface, bleach solution and a material that ARMA says must never be pressure washed. That's three separate ways to lose money or get hurt.