When homeowners look to clean the exterior of their property, two terms are used constantly: soft washing and water blasting. While they sound similar, these methods are not interchangeable. Choosing the wrong one can lead to damaged paint, water intrusion, cracked surfaces, and expensive repairs.
This guide explains the difference between soft washing and water blasting, when each method should be used, and how to make the right decision for your home.
What Is Soft Washing?
Soft washing is a low-pressure exterior cleaning method that uses specialised detergents to break down and kill organic growth such as mould, mildew, algae, and bacteria. Instead of relying on force, soft washing relies on chemistry + time.
The solution is applied at low pressure, allowed to dwell, and then gently rinsed away.
Soft washing is ideal for:
- House washing
- Painted weatherboards
- Stucco and plaster cladding
- Fibre cement (Hardiplank)
- Soffits and fascia
- Window frames and joinery
- Fences
- Some roof types (with treatment)
Key benefits of soft washing:
- Safe for paint and coatings
- Kills mould and algae at the root
- Longer-lasting results
- Reduces regrowth
- Prevents water from entering wall cavities
- Extends the life of exterior paint
Soft washing is the recommended method for most house exteriors.
What Is Water Blasting?
Water blasting (also known as pressure washing) uses high-pressure water to physically remove dirt, grime, moss, oil stains, and surface buildup. This method relies on force rather than detergents.
Because of the pressure involved, water blasting must only be used on hard, durable surfaces.
Water blasting is best for:
- Driveways
- Paths and pathways
- Concrete surfaces
- Pavers and brickwork
- Patios and courtyards
- Retaining walls
- Some fences (depending on condition)
Key benefits of water blasting:
- Quickly removes heavy dirt and grime
- Excellent for oil stains and tyre marks
- Restores concrete and paving
- Improves safety by removing slippery algae
Water blasting is not suitable for most house walls.
Why Using the Wrong Method Causes Damage
One of the biggest mistakes homeowners make is using high pressure where soft washing should be used.
Problems caused by incorrect water blasting:
- Stripped or chipped paint
- Water forced behind cladding
- Damaged weather seals
- Cracked plaster systems
- Timber swelling or rot
- Reduced paint lifespan
- Voided manufacturer warranties
Damage often isn’t visible immediately — it can take months to appear as bubbling paint, damp patches, or internal mould.
Soft Washing vs Water Blasting – Side-by-Side Comparison
| Feature | Soft Washing | Water Blasting |
|---|---|---|
| Pressure level | Low | High |
| Uses detergents | Yes | No (or minimal) |
| Kills mould & algae | Yes | No |
| Safe for house walls | Yes | No |
| Safe for paint | Yes | No |
| Best for concrete | No | Yes |
| Long-lasting results | Yes | Short-term |
| Risk of damage | Very low | High if misused |
Which Method Should You Use on Each Surface?
House walls & cladding
Soft washing only
Roofs
- Moss treatment or soft wash (never high pressure)
Driveways & paths
Water blasting
Patios & courtyards
Water blasting
Decks
Low-pressure wash or soft washing depending on timber condition
Fences
Soft washing or low pressure only
Gutters
Manual cleaning + flushing (not blasting)
Why Soft Washing Lasts Longer Than Water Blasting
Water blasting removes surface grime but does not kill mould or algae roots. This means growth often returns within weeks or months.
Soft washing:
- Breaks down organic growth at the source
- Slows regrowth dramatically
- Keeps surfaces cleaner for longer
- Reduces how often cleaning is needed
That’s why professional house washing relies on soft washing, not pressure.
Why DIY Exterior Cleaning Often Fails
DIY pressure washers are one of the most common causes of exterior damage.
Common DIY mistakes include:
- Using too much pressure
- Holding the nozzle too close
- Forcing water upward under cladding
- Stripping paint unknowingly
- Damaging timber and seals
Without proper training, it’s easy to cause thousands of dollars in damage trying to save a few hundred.
When You Actually Need Both Methods
Most homes benefit from a combination of soft washing and water blasting.
A professional exterior clean often includes:
- Soft washing the house
- Water blasting the driveway and paths
- Cleaning gutters
- Treating the roof
- Washing decks and fences appropriately
Using the right method for each surface gives the best result and protects your property.
How to Know Which Method Your Home Needs
If your home has:
- Green or black staining on walls → Soft washing
- Slippery concrete → Water blasting
- Mould regrowth every few months → Soft washing
- Oil stains or tyre marks → Water blasting
- Faded or peeling paint → Soft washing (gentle)
If you’re unsure, never guess — using the wrong method can be costly.
Professional Exterior Cleaning Makes the Difference
Professional exterior cleaning services:
- Use adjustable pressure systems
- Choose the correct method for each surface
- Apply safe, biodegradable detergents
- Protect paint, timber, and cladding
- Deliver longer-lasting results
- Prevent damage and regrowth
Exterior cleaning done correctly is preventative maintenance, not cosmetic work.
Request a Quote for Professional Exterior Cleaning
If you want your home cleaned safely and correctly — using the right method for every surface — professional exterior cleaning is the smart choice.
📩 Request a Quote:
👉 https://www.metrowaterblasting.co.nz/
📞 Call anytime: 0800 997 997