One of the most common questions homeowners ask when booking exterior cleaning is:
“Should I use soft washing or water blasting?”
The short answer is: it depends on the surface.
Using the wrong cleaning method can cause serious and expensive damage — from stripped paint and cracked cladding to etched concrete and water intrusion behind walls. Understanding the difference between soft washing and water blasting is essential for protecting your home, especially in New Zealand’s varied climates.
This guide explains what each method is, when it should be used, when it should never be used, and how professional exterior cleaners choose the right approach for each surface.
What Is Soft Washing?
Soft washing is a low-pressure cleaning method that uses specialised detergents to break down and remove organic growth such as mould, mildew, algae, and bacteria.
Instead of relying on force, soft washing works by:
- Killing mould and algae at the root
- Loosening grime and contaminants
- Allowing gentle rinsing without damage
Pressure levels used in soft washing are often similar to a garden hose, making it safe for delicate surfaces.
What Is Water Blasting?
Water blasting (also called pressure washing) uses higher pressure water to physically remove dirt, grime, algae, and surface buildup.
It is highly effective on hard, durable surfaces that can handle pressure without damage.
When used correctly, water blasting:
- Restores concrete and paving
- Removes slippery algae
- Improves safety and appearance
When used incorrectly, it can cause permanent damage.
Why Choosing the Right Method Matters
The biggest mistake homeowners make is assuming more pressure = better cleaning. In reality, excessive pressure is one of the fastest ways to damage a property.
Incorrect cleaning methods can cause:
- Water forced behind cladding
- Paint stripping and premature repainting
- Cracked or etched concrete
- Roof damage and leaks
- Accelerated mould regrowth
Professional exterior cleaning is about using the least aggressive method that achieves the best result.
When Soft Washing Is the Correct Choice
Soft washing is the safest and most effective option for surfaces that can be damaged by pressure.
House Washing
House exteriors should always be soft washed.
👉 Auckland House Washing:
https://www.metrowaterblasting.co.nz/house-wash-auckland/
👉 Christchurch House Washing:
https://www.metrowaterblasting.co.nz/house-wash-christchurch/
👉 Hamilton House Washing:
https://www.metrowaterblasting.co.nz/house-washing-hamilton/
Why soft washing is essential:
- Prevents water entering wall cavities
- Protects paint and cladding
- Removes mould instead of spreading it
- Delivers longer-lasting results
High-pressure washing house walls is one of the most common causes of exterior damage in NZ homes.
Roof Cleaning (Most Roof Types)
Roofs should never be aggressively water blasted.
👉 Roof Cleaning Auckland:
https://www.metrowaterblasting.co.nz/roof-cleaning-auckland/
👉 Roof Cleaning Christchurch:
https://www.metrowaterblasting.co.nz/roof-cleaning-christchurch/
👉 Roof Cleaning Tauranga:
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Soft washing and low-pressure treatments:
- Kill moss and lichen at the root
- Prevent moisture retention
- Protect tiles and metal coatings
- Reduce leak risk
For preventative care, moss treatment is critical:
👉 https://www.metrowaterblasting.co.nz/roof-moss-treatment/
Fences
Painted and timber fences benefit from soft washing.
👉 Fence Cleaning Auckland:
https://www.metrowaterblasting.co.nz/fence-cleaning-auckland/
👉 Fence Cleaning Tauranga:
https://www.metrowaterblasting.co.nz/fence-cleaning-tauranga/
Soft washing:
- Preserves paint
- Prevents timber splintering
- Extends fence lifespan
When Water Blasting Is the Right Choice
Water blasting is ideal for hard surfaces that can withstand pressure.
Driveways, Paths & Patios
👉 Water Blasting Auckland:
https://www.metrowaterblasting.co.nz/water-blasting-auckland/
👉 Water Blasting Christchurch:
https://www.metrowaterblasting.co.nz/water-blasting-christchurch/
Water blasting:
- Removes algae and grime
- Restores surface appearance
- Improves traction and safety
Correct pressure control is essential to avoid surface damage.
Concrete Cleaning
👉 Concrete Cleaning Auckland:
https://www.metrowaterblasting.co.nz/concrete-cleaning-auckland/
👉 Concrete Cleaning Tauranga:
https://www.metrowaterblasting.co.nz/concrete-cleaning-tauranga/
Concrete cleaning benefits:
- Removes embedded dirt and stains
- Reduces slip hazards
- Extends surface lifespan
Excessive pressure can etch concrete, leaving permanent marks — which is why professional control matters.
Decks (With Care)
👉 Deck Cleaning Auckland:
https://www.metrowaterblasting.co.nz/deck-cleaning-auckland/
👉 Deck Cleaning Queenstown:
https://www.metrowaterblasting.co.nz/deck-cleaning-queenstown/
Decks may use very low pressure water blasting or soft washing depending on timber condition.
Incorrect pressure:
- Raises timber fibres
- Causes splintering
- Shortens deck life
Professional assessment determines the safest approach.
Why DIY Pressure Washing Causes So Much Damage
DIY pressure washers are responsible for a large percentage of exterior damage.
Common DIY mistakes include:
- Using maximum pressure settings
- Holding the nozzle too close
- Using the wrong spray tip
- Cleaning delicate surfaces with force
- Forcing water into joins and seals
The damage often isn’t visible immediately — but shows up later as paint failure, moisture problems, or leaks.
Which Method Lasts Longer?
Soft washing typically provides longer-lasting results on organic growth because it:
- Kills mould and algae at the root
- Reduces rapid regrowth
- Prevents spores from spreading
Water blasting removes visible buildup but may not eliminate underlying growth unless used with treatments.
The best results often come from combining methods correctly, surface by surface.
Climate Matters When Choosing the Method
Different regions require different approaches:
- Auckland & Tauranga: High humidity → soft washing critical
- Christchurch: Cold and damp → soft washing before winter
- Hamilton: Inland moisture → balanced approach
- Queenstown: Alpine climate → low-pressure methods essential
Using pressure incorrectly in colder or wetter climates increases moisture retention and damage risk.
How Professionals Choose the Right Method
Professional exterior cleaners assess:
- Surface type
- Material condition
- Age of paint or coating
- Level of contamination
- Weather conditions
- Surrounding vegetation
The goal is always:
Maximum clean, minimum pressure.
Soft Washing vs Water Blasting – Quick Summary
Soft Washing is best for:
- House walls
- Roofs
- Fences
- Delicate painted surfaces
Water Blasting is best for:
- Concrete
- Driveways and paths
- Patios and courtyards
- Some decks (with care)
Using the wrong method can turn a simple clean into an expensive repair.
Why Professional Exterior Cleaning Is Worth It
Professional services ensure:
- Correct method for every surface
- Safe pressure levels
- No hidden damage
- Longer-lasting results
- Reduced regrowth
- Full property protection
Exterior cleaning done properly is preventative maintenance — not just cosmetic work.
Request a Quote for Professional Exterior Cleaning
If you’re unsure which method your property needs, a professional assessment is the safest place to start.
👉 Request a Quote:
https://www.metrowaterblasting.co.nz/
📞 Call anytime: 0800 997 997