Typical Surfaces:
Driveways, sidewalks, patios, pool decks, stairs, retaining walls, pavers

Operating Ranges

• PSI: 2,500 – 3,200 PSI

• GPM: 4.0 – 6.5 GPM

• Nozzle Selection: 25°–40° fan tips (surface cleaners preferred for flatwork)

Dwell Time

• 5–15 minutes, depending on:

  • Embedded traffic film

  • Organic staining depth

  • Concrete porosity and age

• Dwell time is used to reduce mechanical pressure, not replace it.

Recovery & Runoff Control

• Residential jobs typically rely on managed directional runoff

• Water is routed away from:

  • Foundations

  • Garage thresholds

  • Landscaping beds

• Sensitive areas may require temporary berming or water diversion

Risk Management

• Excess PSI can:

  • Etch concrete

  • Expose aggregate

  • Strip joint sand from pavers

• Proper GPM allows cleaning with flow instead of force

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Sodium Hypochlorite (SH) Use in Professional Pressure Washing

 

Standards for Dunwoody

In professional pressure washing, SH is used as a cleaning aid — not a substitute for pressure or flow. Correct dilution allows contaminants to be released from the surface so they can be rinsed away with lower mechanical stress.

Key principle:
Higher SH does not equal better cleaning — it increases risk.

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Residential Pressure Washing — Typical SH Ranges

Common Surfaces:
Concrete driveways, sidewalks, patios, pool decks, retaining walls

Typical Working SH Strength

• 0.5% – 1.0% SH (post-mix at surface)

Why This Range Matters

• Removes:

  • Organic growth

  • Light mildew staining

  • Traffic film

• Allows cleaning at lower PSI, reducing:

  • Etching

  • Aggregate exposure

  • Paver joint erosion

Risks of Over-Application

• Surface bleaching

• Premature concrete drying and micro-fracturing

• Damage to adjacent landscaping

• Accelerated oxidation of nearby metals