Regular exterior house washing removes mould, algae, and dirt that age a home prematurely — and in NZ's damp climate, it's one of the most cost-effective maintenance tasks you can do. Here's what house washing costs in NZ in 2026 and what method is right for your cladding.
House Washing Cost NZ 2026
| Service | Typical cost |
|---|---|
| Soft wash — 3-bedroom home exterior | $350–$700 |
| Soft wash — 4-bedroom / large home | $500–$1,000 |
| Waterblast — 3-bedroom home exterior | $300–$650 |
| Waterblast + soft wash combo | $450–$900 |
| Roof wash (soft wash, moss treatment) | $400–$900 |
| Driveway waterblast (per m²) | $5–$15/m² |
| Deck wash (per m²) | $8–$20/m² |
| Fence wash (per linear metre) | $8–$18/lm |
| Moss / mould treatment (biocide only) | $200–$500 |
All prices GST inclusive. Multi-storey or complex rooflines add 20–40%. Auckland 15–20% above.
Soft Wash vs Waterblasting
This is the key choice for house washing — and many NZ homeowners use the wrong method for their cladding type.
Soft Wash
Low-pressure application of cleaning solution (typically sodium hypochlorite-based biocide mixed with surfactant) that kills and removes biological growth. The solution does the work, not the pressure.
Best for: - Painted weatherboard (high pressure damages paint and forces water into joints) - Plaster / stucco cladding (pressure can damage render surface) - Monolithic cladding (high pressure can force water into hairline cracks) - Roofs (pressure damages roofing iron and forces water under laps) - Painted or coated surfaces
How it works: Solution is applied at low pressure (similar to a garden hose), dwells for 15–30 minutes to kill biological matter, then rinsed off. On most surfaces, no scrubbing is needed.
Waterblasting (High Pressure Washing)
High-pressure water (typically 2,000–4,000 PSI) physically blasts dirt, moss, and loose paint off surfaces.
Best for: - Concrete driveways and paths - Brick and unpainted masonry - Timber decks (before staining — opens grain) - Fences (bare or lightly coated timber) - Gutters (internal flush)
Not suitable for: - Painted weatherboard (strips paint, forces water in) - Rendered or plaster cladding (damages surface) - Roof iron (damages paint, can bend or crack flashings) - Soft brick or older masonry (erodes mortar)
The mistake: Many NZ homeowners request waterblasting when they mean exterior cleaning. A reputable house washer will specify the right method for each surface — be cautious of anyone who waterblasts everything regardless of cladding type.
How Often Should You Wash Your House?
| Location / condition | Recommended frequency |
|---|---|
| South Island, shaded (mould prone) | Every 12–18 months |
| North Island, sheltered | Every 2 years |
| Coastal (salt, humidity) | Every 12 months |
| Full sun, exposed | Every 2–3 years |
| Pre-sale / post-winter | As needed |
NZ's humidity and mild temperatures create ideal conditions for mould, algae, and lichen. A green or black film on the south-facing walls of most NZ homes is biological growth — not dirt — and requires biocide, not just water.
What's in House Wash Solution?
Professional house wash solution typically contains: - Sodium hypochlorite (bleach): 2–5% concentration — kills mould, algae, and lichen at the root - Surfactant (detergent): Helps the solution wet and cling to vertical surfaces - Water: Dilutes to working concentration
DIY versions: Diluted bleach (1 part bleach to 4 parts water) with dish soap is an effective DIY house wash for accessible surfaces. Apply with a garden sprayer, dwell, rinse.
Warning: Sodium hypochlorite at working concentration will kill plants, bleach coloured surfaces, and irritate skin and eyes. Protect plants with water before and after, and wear gloves and eye protection.
Exterior Cladding Types and Care
| Cladding | Method | Notes |
|---|---|---|
| Painted weatherboard | Soft wash only | High pressure strips paint and forces water into lap joints |
| Brick veneer | Light waterblast or soft wash | Avoid pointing mortar with high pressure |
| Roughcast plaster | Soft wash | High pressure can damage render surface |
| Monolithic (direct-fix plaster) | Soft wash only | Never waterblast — forces water into any cracks |
| Fibre cement (Linea, Harditex) | Soft wash | Check manufacturer guidance |
| Vinyl weatherboard | Soft wash or gentle pressure | Check for any cracked or loose joints before washing |
| Exposed aggregate concrete | Waterblast | Can handle high pressure |
Preparing for a House Wash
Before the washer arrives: - Close all windows and doors - Move vehicles clear of the house - Cover or move outdoor furniture and plants (or water them well first) - Notify the company of any known damaged cladding, loose boards, or weathertightness concerns
After washing: Check windows and door seals for any water ingress. Note any paint that lifted or cladding that let water through — these are maintenance items to address before the next wash or paint.
Find house washing services near you: Waterblasters NZ | Post Your House Wash Job Free
Frequently Asked Questions
How much does house washing cost in NZ? A 3-bedroom home exterior (soft wash): $350–$700. A 4-bedroom: $500–$1,000. Waterblasting a driveway: $5–$15/m². Most companies offer package deals covering house + driveway + deck in one visit.
How often should I wash the outside of my house in NZ? Every 1–2 years for most NZ homes. Coastal, shaded, or south-facing homes need washing more frequently (every 12 months). Regular washing prevents biological growth from establishing a permanent hold and keeps exterior paint in better condition.
Is soft washing or waterblasting better for painted weatherboard? Soft wash — always. Waterblasting painted weatherboard strips paint, forces water into lap joints, and can cause swelling and rot. Soft washing with a biocide solution effectively removes mould and algae without damaging the surface.
Can I wash my own house in NZ? Yes — DIY is practical for single-storey homes with accessible walls. Use a garden sprayer for soft wash solution (diluted bleach + dish soap), work in sections, and rinse well. Avoid spraying solution on plants. For anything above single-storey or with complex rooflines, a professional with proper equipment is safer.
What is the black or green on my house walls in NZ? Biological growth — mould (black), algae (green), or lichen (grey-green crusty patches). All common in NZ's humid climate, especially on south-facing or shaded walls. A biocide-based soft wash kills the biological matter at the root. Waterblasting alone removes the visible growth but doesn't kill the roots — it returns faster.
Related: Waterblasting Cost NZ | Exterior House Painting Cost NZ | Post a Job Free