One of the most common questions homeowners ask is:
“How often should I wash my house?”
The answer depends on where you live, your home’s exposure, and the surrounding environment. In New Zealand, climate plays a major role in how quickly mould, algae, and grime build up on exterior surfaces.
In this guide, we break down how often homes should be professionally washed — and why regular maintenance can save you thousands in long-term repair costs.
The General Rule for Most NZ Homes
For most residential properties in New Zealand:
Professional house washing is recommended every 12–18 months.
This timeframe prevents heavy mould buildup, protects paint, and keeps your home looking well maintained.
However, some properties require more frequent cleaning.
Coastal Homes (Every 12 Months)
If your home is near the ocean — such as in Auckland’s coastal suburbs or Wellington’s bays — salt air accelerates surface deterioration.
Salt residue:
- Breaks down paint
- Encourages mould growth
- Causes corrosion on metal fixtures
Annual soft washing is strongly recommended for coastal properties.
👉 Learn more about professional house washing here:
https://www.metrowaterblasting.co.nz/house-wash-auckland/
Shaded or Tree-Covered Homes (Every 12 Months)
Homes surrounded by trees or with limited sun exposure experience:
- Heavy algae buildup
- Persistent moisture retention
- Mould growth on southern-facing walls
Areas like West Auckland, parts of Hamilton, and bush-lined Wellington suburbs commonly require annual washing.
Urban & High-Traffic Areas (Every 12–18 Months)
Homes near busy roads accumulate:
- Traffic pollution
- Dust
- Soot buildup
- General grime
Central city homes may not grow heavy moss, but they still benefit from regular cleaning to prevent surface staining.
Newer Homes (Preventative Every 18 Months)
Even if your home looks clean, preventative soft washing every 18 months:
- Protects paint finishes
- Stops mould before it becomes visible
- Maintains resale value
Waiting until visible staining appears usually means more aggressive treatment is required.
Signs Your House Needs Washing Now
Even if you’re unsure of the timeframe, your house may need washing if you notice:
- Green or black streaks
- Mould around windows
- Dirt buildup under eaves
- Fading paint
- Slippery exterior surfaces
If these signs are visible, it’s time for professional cleaning.
Why Waiting Too Long Costs More
Delaying house washing can lead to:
- Paint breakdown
- Timber deterioration
- Water intrusion issues
- Higher repainting costs
- Structural damage over time
A professional wash is significantly cheaper than repainting your entire home.
What’s the Safest Cleaning Method?
Most residential homes should be cleaned using soft washing, not high-pressure water blasting.
Soft washing:
- Kills mould and algae at the root
- Protects paint and cladding
- Prevents rapid regrowth
- Delivers longer-lasting results
👉 Learn about the difference here:
https://www.metrowaterblasting.co.nz/water-blasting-auckland/
What About Roofs & Gutters?
Exterior maintenance should include:
- Roof inspections every 2–3 years
- Moss treatment when visible
- Annual gutter cleaning
👉 Roof cleaning services:
https://www.metrowaterblasting.co.nz/roof-cleaning-auckland/
👉 Gutter cleaning services:
https://www.metrowaterblasting.co.nz/gutter-cleaning-auckland/
Keeping these maintained prevents staining and overflow damage to walls.
The Smart 2026 Approach to Exterior Maintenance
In 2026, preventative maintenance is more important than ever due to rising paint and material costs.
Most homes benefit from:
- House washing: Every 12–18 months
- Roof treatment: Every 2–3 years
- Gutter cleaning: Annually
- Concrete cleaning: As required
Routine maintenance protects your biggest investment — your home.
Not Sure If It’s Time?
If you’re unsure whether your house needs washing, a quick assessment can help determine:
- Level of mould growth
- Surface condition
- Best cleaning method
- Recommended frequency
Or request a no-obligation quote online.