Lichen and moss are silent destroyers of New Zealand roofs. Learn why roof washing is essential, how often it should be done, the difference between soft wash and high-pressure methods, and what it costs — with expert advice from our NZ team.
In This Article
1Why Lichen & Moss Are a Serious Problem
New Zealand's temperate, often damp climate is a paradise for lichen, moss, and algae — and your roof is their preferred habitat. Lichen in particular is one of the most damaging organisms that can colonise a roof surface. Unlike moss, which can be brushed off relatively easily, lichen bonds chemically to roofing materials and must be treated and professionally removed.
Across Christchurch and Queenstown, the combination of seasonal moisture, shade from nearby trees, and UV exposure creates almost perfect conditions for organic growth on all roof types — from concrete tiles and Colorsteel to Decramastic and long-run steel.
2How Lichen Damages Your Roof
Lichen is not just unsightly — it is structurally destructive:
Moisture retention: Lichen and moss hold moisture against roofing material, accelerating corrosion on metal roofs and promoting freeze-thaw cracking on concrete tiles.
Chemical etching: Lichen secretes organic acids that etch into concrete tiles and stone coatings, permanently degrading surface hardness.
Weight loading: A thick coverage of wet moss can add significant weight to older roof structures.
Blocked drainage: Growth around flashings and valleys traps debris and blocks water flow, leading to ponding and potential leaks.
Voided warranties: Many roofing material warranties specify that failure caused by unremoved biological growth is not covered.
3Soft Wash vs High-Pressure: Which Is Right for Your Roof?
This is the most important technical question in roof washing — and the answer depends entirely on your roof type.
Soft Wash (Low-Pressure + Chemical Treatment)
Soft washing uses low water pressure combined with professional-grade biocide solutions that kill lichen, moss, and algae at the root. The dead organic matter then weathers off naturally over several weeks. This is the recommended method for:
Concrete and terracotta tiles
Decramastic tiles
Colorsteel (ZINCALUME® / Colorbond-equivalent)
Metal roofing with existing coatings
Soft wash eliminates the risk of physical damage while delivering long-lasting results.
High-Pressure Washing
High-pressure washing is appropriate for certain commercial roofing and for removing heavy, loose debris prior to treatment. It is NOT appropriate as a standalone method on tiles as it removes surface granules and coating, voiding manufacturer warranties and shortening roof life.
Rise & Shine technicians assess each roof individually and apply the correct method — we never use a one-size-fits-all approach.
4How Often Should You Wash Your Roof in NZ?
The general recommendation for New Zealand properties is a professional roof wash every 2–3 years in most areas, reducing to every 1–2 years in:
High-shade environments (near trees or steep valley walls)
High-rainfall regions like the West Coast and Fiordland
Properties near the coast (salt air accelerates growth)
Christchurch and Queenstown suburbs with prevailing moisture from the Southern Alps
In between professional washes, applying a post-clean inhibitor treatment significantly slows regrowth. Rise & Shine includes this as part of our roof wash service.
5DIY vs Professional Roof Washing
Every year, New Zealand homeowners are injured or killed attempting to clean their own roofs. Beyond the obvious safety risks, DIY roof cleaning carries several practical problems:
Wrong technique: Using high-pressure on tiles strips protective coatings and accelerates wear.
Inadequate treatment: Consumer biocide products are significantly weaker than professional-grade solutions, meaning faster regrowth.
No safety equipment: Working at height without correct fall-arrest gear is illegal and dangerous.
No insurance: If you damage your roof or injure yourself, domestic insurance policies often don't cover DIY maintenance injuries.
Professional roof washing by a fully insured team like Rise & Shine costs a fraction of even a minor roof repair — and comes with a guarantee.
6What Does Roof Washing Cost in NZ?
Roof washing costs in New Zealand vary based on:
Roof size (m² of total area)
Roof pitch (steeper = more difficult and time-consuming)
Degree of lichen/moss coverage
Roof type and access difficulty
Location (Christchurch vs Queenstown pricing may differ slightly due to travel)
As a general guide for Christchurch properties:
Small single-storey home (80–120m²): $350–$550
Average two-storey home (120–200m²): $550–$900
Large homes and commercial buildings: Quote-based
All Rise & Shine quotes are free and obligation-free. We also offer multi-service discounts when combining roof washing with driveway, house, or deck cleaning.
7After the Wash: Keeping Your Roof Clean Longer
The period immediately after a professional wash is the best time to apply preventative treatments:
Inhibitor spray: A professional-grade zinc or copper-based inhibitor applied post-wash dramatically slows lichen and moss regrowth — extending the clean by 12–24 months.
Tree trimming: Reducing overhanging branches limits shade and leaf debris — two key factors in organic growth.
Gutter maintenance: Blocked gutters cause water to back up under tiles. Combined with a roof wash, a gutter clean is a smart investment.
Regular inspections: Annual visual checks (from the ground or safely from a ladder) let you catch early growth before it becomes a costly treatment job.
Rise & Shine offers a maintenance reminder service — we'll contact you when your property is due for its next clean, so you never have to worry about letting it get too far gone.
Tagged:
Related Services
Need advice on Roof Care?
Get a free, no-obligation expert recommendation and quote from the Rise & Shine Water Blasting team. Serving Christchurch & Queenstown.
