Softwashing and pressure washing are two methods used to clean the exterior surfaces of homes, but they differ in terms of technique, pressure, and the types of surfaces they’re suited for.
Softwashing:

Low Pressure: Softwashing uses low-pressure water combined with cleaning solutions to remove dirt, mold, mildew, and algae from surfaces. The pressure is typically around 100-500 PSI (pounds per square inch).
Cleaning Solutions: It relies heavily on biodegradable cleaning detergents, often including sodium hypochlorite (bleach), surfactants, and water, to break down contaminants on surfaces.
Surface Application: Softwashing is ideal for delicate surfaces such as:
Roofs (asphalt shingles, tile)
Vinyl siding
Stucco
Wood (decking or fencing)
Screens or windows
Long-lasting Results: The cleaning solutions used in softwashing not only clean the surface but also help to prevent the regrowth of mold, mildew, and algae, offering longer-lasting results.
Less Risk of Damage: Because it uses lower pressure, there's less risk of damage to surfaces like roofing or siding that can be harmed by high-pressure washing.

Pressure Washing:

High Pressure: Pressure washing involves blasting water at high pressure, typically ranging from 1,500 to 4,000 PSI, to remove dirt, grime, and surface stains.
No Detergents Needed: While detergents can be used, pressure washing often relies purely on the power of water to scrub surfaces clean.
Surface Application: It’s best for hard, durable surfaces like:
Concrete (driveways, sidewalks, patios)
Brick
Stone
Metal
Risk of Damage: If used on more delicate surfaces, high-pressure water can cause significant damage, such as stripping paint, denting siding, or damaging roofing materials.
Instant Results: Pressure washing offers immediate visual results, as it can quickly remove visible dirt and stains.

Which Should You Use?

Softwashing is better for more delicate or treated surfaces that need cleaning but could be damaged by high pressure.
Pressure washing is ideal for heavy-duty cleaning of hard surfaces that can withstand the force of high-pressure water.

Many professional cleaning services use both methods depending on the surface and the level of grime buildup.

Softwashing: Detailed Overview

How It Works:
Cleaning Solutions: Softwashing primarily relies on chemical cleaning agents to do the work, while the low-pressure water helps to rinse away the loosened dirt and contaminants.
Detergents: These solutions typically include surfactants (to loosen dirt), sodium hypochlorite (to kill mold, mildew, algae), and water. These biodegradable solutions are usually left on the surface for a few minutes, allowing them to break down contaminants before being rinsed off.

Ideal Uses:
Roofs: Asphalt shingles and tile roofs are prone to mold, algae, and moss growth. Softwashing safely removes these without causing physical damage.
Vinyl Siding: Vinyl can warp or crack under high pressure, making softwashing the safer option.
Stucco and Brick: Delicate stucco surfaces or soft bricks can be damaged by high pressure. Softwashing helps clean them without chipping or breaking.
Wood Surfaces: Softwashing can gently clean wooden decks and fences without splintering or gouging the material.
Windows: The low pressure prevents damage to glass and seals, while still effectively cleaning grime, mold, and mildew.

Pros:
Safe for Delicate Surfaces: Minimal risk of damage to delicate materials.
Long-lasting Results: Because softwashing kills organisms like mold and algae, it provides a longer-lasting clean.
Environmental Friendly Options: The detergents used are often biodegradable.
Lower Water Usage: Softwashing typically uses less water than pressure washing.

Cons:
Slower Process: Because softwashing relies on chemicals and low pressure, it can take longer than pressure washing to complete.
Requires Chemical Application: The use of chemicals means you must ensure proper dilution and avoid overuse, especially near plants and landscaping.

Pressure Washing: Detailed Overview

How It Works:
High Pressure: Pressure washing uses highly pressurized water, without relying much on cleaning agents. It is best for removing surface-level dirt, grime, and stains through sheer force.
Pressure Levels: The pressure can range from 1,500 PSI for lighter jobs to over 4,000 PSI for heavy-duty cleaning.

Ideal Uses:
Concrete Surfaces: Driveways, sidewalks, patios, and parking lots can easily be cleaned using pressure washing. It’s powerful enough to remove tough stains like oil, rust, and deep-seated grime.