Your roof takes the brunt of Wellington’s wild weather — high winds, salty air, constant rain, and shade from surrounding bush all combine to create the perfect environment for moss, mould, and lichen to thrive. Over time, this not only ruins your roof’s appearance but also shortens its lifespan.
At Metro Water Blasting, we provide safe, effective roof cleaning and moss treatment services across Wellington’s northern suburbs, including Johnsonville, Newlands, Khandallah, and Ngaio. Whether you have a tiled roof, iron, or decramastic, we clean it without damage — and help protect your home from long-term moisture issues.
👉 Learn more or book: Roof Cleaning Wellington
Why Northern Suburbs Are Moss Hotspots
These areas are notorious for damp, shady roof conditions:
- Khandallah, Ngaio & Wilton – Dense bush and high humidity lead to black mould and thick green moss
- Johnsonville & Newlands – High wind exposure spreads spores across rooftops and gutters
- Broadmeadows & Paparangi – Elevated locations with shaded valleys encourage fast lichen growth
- Kaiwharawhara & Crofton Downs – Surrounded by trees and often hidden from full sunlight, leading to organic buildup
Unlike algae or dust, moss physically damages your roof. It lifts tiles, causes corrosion on metal roofs, blocks drainage, and promotes leaks.
What We Remove from Roofs
Our treatment removes:
- Green moss
- Black mould and mildew
- White lichen
- Dust, soot, and road grime
- Organic debris from trees and leaves
We use a non-abrasive soft treatment, applying a biodegradable moss killer that kills spores at the root. It works over weeks and prevents regrowth — no high-pressure blasting, no damage to fragile surfaces.
👉 Related post: Roof Moss Treatment in Wellington
Roof Types We Service
We clean and treat all common Wellington roofs:
- Corrugated iron (Colorsteel, Zincalume)
- Tiled roofs (concrete or terracotta)
- Decramastic (chip-coated metal)
- Painted metal roofs
- Flat roofs and skillion roofs
- Multi-storey and steep access homes
Our team is trained in harness use, ladder safety, and we follow strict no-footfall rules for fragile surfaces. If roof access isn’t safe, we apply treatment from the ground or gutter line using long-reach equipment.
Real Case Studies from the North
✅ Johnsonville – A 1990s decramastic roof had thick moss and visible water staining. We treated it with a soft biocide, and within 4–6 weeks the moss died off naturally, restoring the roof’s original texture.
✅ Khandallah – A Colorsteel roof was blackened with mould and blocked gutters. We treated the entire roofline, cleared the downpipes, and helped prevent moss from spreading again.
✅ Newlands – A tiled roof under overhanging trees had patches of lichen and moss. Our low-pressure treatment safely cleaned it over time, without dislodging any tiles.
👉 Bonus blog: Spring Maintenance Tips for Wellington Homes
👉 Also see: Gutter Cleaning Checklist for Wellington
Why Professional Roof Cleaning Matters
DIY roof washing is risky and often counterproductive:
- High pressure damages tiles and paint
- Improper treatment doesn’t kill spores — they return in months
- Unsafe roof access puts homeowners at risk
- Incomplete jobs leave streaks and untreated zones
We deliver full coverage with eco-safe treatments, proper equipment, and experience navigating Wellington’s steep, tricky roofs.
How Our Roof Cleaning Works
- Inspection – We assess the roof type, pitch, and condition
- Treatment – Apply moss and lichen control solution (no pressure washing)
- Time to work – Moss dies off gradually over 4–6 weeks
- Optional follow-up – Light rinse or reapplication if needed (usually not required)
- Add-on cleaning – Gutter clears, fascia cleaning, or house washing can be bundled
When to Clean Your Roof
- Every 18–24 months in damp, shaded suburbs
- Pre-sale preparation — a clean roof boosts property value
- After storms or winter seasons
- When moss is visible from the ground or driveway
- If gutters keep overflowing due to moss runoff
Regular roof cleaning helps extend your roof’s life and prevents more expensive repairs.
Add-On Services for Full Protection
Bundle roof cleaning with:
- Gutter Cleaning – Prevent blocked pipes and water damage
- House Washing – Remove runoff stains from siding
- Fence & Deck Cleaning – Clean moss from rear yard structures
- Driveway & Path Cleaning – Especially when runoff discolours your concrete
FAQs About Roof Moss Treatments
Q: Do you water blast the roof?
No — we use a non-pressure, eco-safe chemical treatment that doesn’t damage paint or tiles.
Q: How long until the moss disappears?
Typically 4–6 weeks for moss to dry, die, and wash off naturally with rain. Lichen may take longer.
Q: Can I walk on the roof after treatment?
We don’t recommend it — the treatment can be slippery. It’s best to leave it alone and let the product work.
Q: Is this safe for pets and gardens?
Yes. Our treatment is biodegradable and safe when applied by our trained team.
Book Your Northern Suburbs Roof Clean Today
Protect your property and extend your roof’s lifespan with a professional roof clean. Whether you’re in Johnsonville, Newlands, Khandallah, or Ngaio, our Wellington-based team can safely treat and restore your roof — with no pressure, no mess, and long-lasting results.
📍 Local Wellington Crew
📞 Call 0800 997 997 – Open 24/7
📅 Free quote: Roof Cleaning Wellington