Rochester Pressure Wash · Glossary
pressure washing and soft washing glossary
Plain-English definitions for the technical terms you'll see in quotes, proposals, and inspection reports. Bookmark this when you're comparing bids.
- Soft wash
- Low-pressure (60-100 PSI) application of biodegradable cleaning chemistry. Used on siding, roofs, painted surfaces.
- Pressure wash
- High-pressure (1500-3500 PSI) water spray. Used on concrete, brick, hardscape — not siding or shingles.
- PSI
- Pounds per square inch. Pressure rating. Residential machines: 1500-3000. Commercial: 3000-5000.
- GPM
- Gallons per minute. Flow rate. Affects rinse speed more than PSI.
- Surface cleaner
- A flat-bottomed attachment with rotating spray jets. Cleans concrete uniformly without streaks.
- ARMA-recommended cleaning
- The Asphalt Roofing Manufacturers Association mandates low-pressure (<100 PSI) chemistry-based roof cleaning. High pressure = void warranty.
- Algae blooms (Gloeocapsa magma)
- The cyanobacteria responsible for black streaks on roofs. Survives by feeding on limestone in shingles. Soft-wash chemistry kills it at the root.
- Efflorescence
- White crystalline deposit on brick or masonry. Salts migrating to the surface as water evaporates. Surface cleaner + acid wash removes it.
- Pre-treatment
- Applying cleaning chemistry before pressure. Lets the soft-wash chemistry break down dirt + algae before rinse.
- Post-treatment
- Applying a brightener or sealer after cleaning. Common on wood decks to restore color.