Soft Wash & Pressure Washing Glossary

Home / Soft Wash & Pressure Washing Glossary

A quick reference for homeowners and property managers in The Woodlands, TX researching exterior cleaning. These are the terms you’ll see across our site and hear from our team when we’re on the phone or on site.

Soft Washing

A low-pressure cleaning method (typically under 500 PSI) that uses a specialized cleaning solution to kill algae, mold, and mildew at the root, rather than blasting it off with force. This is the method Suds uses on roofs, siding, and other soft surfaces where high pressure can cause damage.

Pressure Washing

A high-pressure water cleaning method (often 1,500-3,000+ PSI) best suited for hard, durable surfaces like concrete driveways, sidewalks, and pavers. Using pressure washing on shingles or siding can strip granules, force water behind panels, or void manufacturer warranties, which is why Suds reserves it for hardscapes.

Gloeocapsa Magma

The scientific name for the blue-green algae responsible for the dark streaks commonly seen on asphalt shingle roofs across the Woodlands and greater Houston area. It feeds on the limestone filler in shingles and spreads via windborne spores, which is why it often shows up on the north-facing, shaded side of a roof first.

Soft Wash Solution

The cleaning mixture used in soft washing, generally a diluted blend of sodium hypochlorite (a controlled-strength bleach solution) and a surfactant that helps it cling to vertical and angled surfaces long enough to work. Concentration and dwell time are adjusted by surface type.

Surfactant

An additive mixed into a soft wash solution that reduces surface tension, allowing the cleaning agent to spread evenly and stick to a roof or wall long enough to break down algae and mildew instead of running off immediately.

Dwell Time

The amount of time a cleaning solution is left on a surface before being rinsed, allowing it to fully break down algae, mold, or mildew. Dwell time varies by surface material, staining severity, and weather conditions.

Efflorescence

A white, chalky mineral deposit that forms on brick, concrete, or stone as water evaporates and leaves salts behind. It’s a common concern on hardscapes and can be addressed as part of a pressure washing service.

Water Reclamation

A system for capturing and containing wastewater during a cleaning job, typically used on commercial sites with strict runoff requirements. It is not a standard part of every job, but Suds can source or rent reclamation equipment for jobs where a property or municipality requires it. See our stormwater compliance guide for more detail.

Rinse-Off Method

A cleaning approach used mainly on hardscapes where a surface is rinsed clean immediately with pressurized water, as opposed to soft washing’s kill-and-release approach where the solution is left to work before a lower-pressure rinse.

Oxidation

A chemical breakdown that occurs on some painted or coated siding materials over time, often showing up as a chalky residue. It’s a different issue from algae or mildew staining and may need a different cleaning approach.

Common Questions

What’s the difference between soft washing and pressure washing?

Soft washing uses low pressure and a cleaning solution to kill algae and mildew at the root, making it safe for roofs and siding. Pressure washing uses high water pressure alone and is better suited for hard surfaces like concrete and pavers.

Why do Woodlands roofs get those dark streaks?

The streaks are caused by Gloeocapsa magma, a blue-green algae that feeds on limestone filler in asphalt shingles. It spreads by windborne spores and tends to show up first on shaded, north-facing roof slopes, which is common throughout the humid Houston area.

Is the cleaning solution used in soft washing safe for landscaping?

Soft wash solutions are diluted and applied with landscaping protection in mind, including pre-rinsing and covering sensitive plants. Ask about our plant protection steps when scheduling.

Do I need water reclamation for a residential job?

No, water reclamation is generally a commercial or municipal requirement, not a residential one. Most homes don’t need it, but Suds can arrange it if a specific property or HOA requires it.