Wrong PSI on the wrong surface can cause $3,000 in damage before you pack up the truck. Aluminum, vinyl, stucco, and pavers all have specific pressure limits -- and most damage happens when contractors treat them like concrete. Here's exactly how to handle each one.

The Quick Answer

Safe PSI ranges for specialty surfaces in pressure washing:

Aluminum siding: 1,000 - 1,500 PSI, 40-degree nozzle
Vinyl siding: 1,300 - 1,500 PSI max, 25-45 degree nozzle, angle downward
Synthetic stucco (EIFS): Under 1,500 PSI, 40-degree nozzle minimum
Traditional (hard coat) stucco: 1,500 - 2,000 PSI, 25-40 degree nozzle
Concrete pavers: 1,000 - 1,500 PSI max, 25-degree nozzle
Clay brick pavers: Under 1,200 PSI, 25-degree nozzle

When in doubt, start lower and work up. You can always add pressure -- you can't undo damage already done.

Pressure Washing Aluminum Siding

Aluminum is one of the more forgiving specialty surfaces, but it's still easy to dent or crease if you get too close. Use 1,000-1,500 PSI with a 40-degree white tip nozzle. Keep the wand at least 12 inches from the surface and move steadily -- don't hover.

Aluminum oxidizes over time, leaving a chalky white residue on the surface. Pre-treat with a low-alkaline detergent and let it dwell 5-10 minutes before rinsing. This loosens oxidation without needing extra pressure to power through it.

Key mistake to avoid: directing the nozzle upward from below. That forces water up under the siding panels and behind the wall, which leads to mold growth inside the structure. Always angle downward or spray straight-on.

Pressure Washing Vinyl Siding

Vinyl is common and deceptively fragile under pressure. Stick to 1,300-1,500 PSI max. Going above 2,500 PSI can force water behind the panels, trapping moisture and causing mold growth inside the walls -- a problem the homeowner won't discover for months.

Use a 25-45 degree nozzle and always angle slightly downward. Never spray upward into the siding seams -- that's how water gets behind the panels. Work top-to-bottom in consistent overlapping passes.

Soft washing is actually the better approach for heavily soiled vinyl. The chemical does the cleaning; the water just rinses. You get a cleaner result with less risk of buckling or panel separation -- and less liability if something goes wrong.

Pressure Washing Stucco

There are two kinds of stucco and they need different treatment. Misidentify the type and you could be cutting into the surface or pulling chunks out of the wall.

Synthetic Stucco (EIFS)

Exterior Insulation and Finishing System (EIFS) is a foam-based synthetic stucco common on homes built after the 1990s. This material is extremely water-sensitive -- it's designed to breathe, not to be saturated. Keep pressure under 1,500 PSI and use a wide-angle nozzle (40 degrees minimum). Never use a 0-degree or 15-degree tip on EIFS.

Soft washing is the safest approach for EIFS. Low pressure plus a mild detergent handles mold and algae without risking the surface. If you see cracks in EIFS before you start, stop. Water intrusion behind compromised EIFS causes serious structural damage -- document it and tell the customer before you touch it.

Traditional Hard Coat Stucco

Hard coat stucco is cement-based and significantly more durable than EIFS. You can use 1,500-2,000 PSI here with a 25-40 degree nozzle. Keep the wand moving and stay at least 10-12 inches from the surface.

Cracked stucco is a no-go. Pressure washing over existing cracks drives water into the wall cavity. Inspect the surface before you start. If there are cracks, photograph them, flag them to the homeowner in writing, and either skip those areas or quote a separate repair referral.

Pressure Washing Pavers

Pavers are low-pressure territory, and the main reason isn't the stone itself -- it's the sand in the joints. Blow out that sand with too much pressure or the wrong nozzle angle, and you're looking at a $500-$2,000 re-sanding job to fix what you caused.

The Interlocking Concrete Pavement Institute (ICPI) recommends staying under 1,500 PSI for concrete pavers, and under 1,200 PSI for clay brick. Use a 25-degree nozzle and hold it at least 12 inches from the surface. Move in wide sweeping strokes, not short bursts in one spot.

Polymeric Sand Pavers Require Extra Care

If the joints have polymeric sand (the kind that hardens after wetting), treat it with even more caution. Polymeric sand can be dislodged under pressure, which creates gaps where weeds take root.

Stay at or below 1,000 PSI near the joints. Avoid directing the spray straight down into the gaps. Work in sweeping passes parallel to the joint lines, not perpendicular to them.

After cleaning, inspect the joints. If sand has shifted, re-sand and re-wet to activate the polymeric binder before the surface dries. Better to catch it during the job than hear about it from the homeowner after.

Bottom Line

Specialty surface pressure washing requires knowing the limits before you start. Contractors who master aluminum, vinyl, stucco, and pavers can charge premium rates because most guys don't know the rules -- or find out the hard way when they're covering damage costs.

If you want to book more specialty surface jobs in your area, try QuoteSnap for free. Add instant pricing to your website so homeowners get a quote and you get a lead -- before they call the next guy.

Specialty Surfaces: Pressure Washing Aluminum, Vinyl, Stucco, and Pavers (2026)