The Complete Guide to Cleaning Different Roof Types in Auckland

If there's one thing Auckland does well, it's variety. Our city's homes span more than a century of architectural styles, from classic Victorian villas to modern architectural builds. And with that variety comes a diverse mix of roofing materials, each with its own characteristics, challenges, and cleaning requirements.

Here's what many homeowners don't realise: the cleaning method that works perfectly on one roof type can cause serious damage to another.

Use high pressure on concrete tiles? You might force water underneath and create leaks. Apply the wrong chemicals to a metal roof? You could accelerate corrosion. Walk across Decramastic tiles without proper care? You'll crack them.

Getting it wrong doesn't just waste money, it can shorten your roof's lifespan and create problems that cost thousands to fix.

In this guide, we'll walk through Auckland's most common roof types and explain exactly how each should be cleaned for the best results without damage.

Understanding Auckland's Roofing Landscape

Before diving into specific materials, it's worth understanding what you're likely to find across Auckland's suburbs.

Drive through Henderson, Massey, or much of South Auckland and you'll see concrete tile roofs dominating the streetscape, these were the go-to choice for developers from the 1960s through to the early 2000s.

Head to newer developments in areas like Hobsonville, Long Bay, or Flat Bush and you'll find Colorsteel and metal roofing on most homes, the modern choice for contemporary builds.

In established suburbs like Mt Eden, Ponsonby, Grey Lynn, and across the North Shore, you'll encounter a mix of everything: asphalt shingles on older homes, clay tiles on character properties, and the occasional Decramastic roof from the 1970s and 80s renovation boom.

Each material responds differently to Auckland's humid, coastal climate,and each requires a tailored approach to cleaning.

Concrete Tile Roofs

Where you'll find them: Henderson, Massey, Manukau, Papatoetoe, Mangere, Pakuranga, and most suburbs developed between 1960–2000.

Concrete tiles are arguably Auckland's most common roofing material, and for good reason. They're durable, fire-resistant, and provide excellent insulation. A well-maintained concrete tile roof can last 50 years or more.

However, concrete's porous nature makes it a magnet for moss, lichen, and algae growth,particularly in Auckland's humid climate.

The Problem with Concrete Tiles

The surface of a concrete tile is full of microscopic pores that absorb and retain moisture. In shaded areas or south-facing sections of your roof, these tiles can stay damp for days at a time, creating perfect conditions for organic growth.

Once moss establishes itself, it acts like a sponge, holding even more moisture against the tile surface. Over time, this constant dampness:

• Breaks down the tile's protective coating
• Allows moisture to penetrate deeper into the concrete
• Creates conditions for the tile to become soft and crumbly
• Can lead to cracking during temperature changes

Lichen is even more problematic. Its root-like structures actually penetrate the tile surface, creating physical damage that remains even after the lichen is removed.

How to Clean Concrete Tiles (The Right Way)

Never use high-pressure washing on concrete tiles.

This is the most common mistake homeowners and inexperienced cleaners make. While blasting the tiles with high pressure might make them look clean immediately, it causes several problems:

Forces water underneath tiles — The overlapping design of tile roofs isn't waterproof; it relies on water running down the surface. High pressure can drive water upward and underneath, leading to leaks.

Strips protective coatings — Concrete tiles are typically coated with a protective sealant. High pressure removes this coating, leaving the porous concrete exposed to the elements.

Damages the tile surface — Pressure washing can etch and erode the concrete itself, making it even more porous and prone to future growth.

The correct approach is low-pressure soft washing.

Soft washing uses a combination of eco-friendly cleaning solutions and low-pressure water application. The chemicals do the work, killing moss, lichen, and algae at the root level, while the gentle pressure rinses everything away without damaging the tiles.

The treatment continues working for weeks after application, with dead organic matter gradually washing away with rainfall. Many treatments also include preventative agents that inhibit regrowth for months or even years.

Why drone cleaning is ideal for concrete tiles:

Beyond the cleaning method, there's another consideration with concrete tiles,foot traffic. Walking on concrete tiles, especially older ones, risks cracking them. Each crack is a potential entry point for water.

Drone-based cleaning eliminates this risk entirely. The drone applies treatment across the entire roof surface without anyone ever stepping on your tiles.

Colorsteel and Metal Roofs

Where you'll find them: Hobsonville, Long Bay, Flat Bush, Silverdale, newer developments across Auckland, plus renovated homes throughout the city.

Metal roofing, whether it's Colorsteel, Zincalume, or other coated steel products, has become the dominant choice for new Auckland homes. It's lightweight, long-lasting, and comes in a huge range of colours and profiles.

But “low maintenance” doesn't mean “no maintenance.”

The Problem with Metal Roofs

While metal roofs don't harbour moss and lichen as readily as concrete, they face their own challenges in Auckland's environment:

Salt spray corrosion — If you live anywhere near the coast (and in Auckland, that's most of us), airborne salt is constantly landing on your roof. Over time, this salt attacks the protective coating on metal roofing, leading to premature corrosion and rust spots.

Oxidation and chalking — Even away from the coast, the painted surface of metal roofing gradually oxidises. You'll notice this as a chalky residue and fading colour. Left unchecked, this oxidation compromises the coating's protective properties.

Debris accumulation — Leaves, dirt, and other debris can accumulate in valleys and against flashings, trapping moisture and creating localised corrosion points.

Algae staining — While less common than on porous surfaces, algae can still establish on metal roofs, particularly in shaded areas. The dark staining is unsightly and can affect the roof's heat-reflective properties.

How to Clean Metal Roofs (The Right Way)

Metal roofs can tolerate more pressure than concrete tiles, but that doesn't mean you should blast them with a high-pressure washer.

The main concerns with metal roof cleaning are:

Avoiding coating damage — Aggressive cleaning can scratch or wear through the protective paint layer, exposing the steel beneath to corrosion.

Using appropriate chemicals — Some cleaning agents can react with metal coatings, causing discolouration or accelerating deterioration. Always use products specifically formulated for coated metal roofing.

Preventing water intrusion — Metal roofs have numerous penetrations (screws, flashings, vents) where water can enter if cleaning is too aggressive.

A combination of appropriate cleaning solutions and moderate-pressure rinsing works best for metal roofs. The cleaning solution should be designed to remove salt deposits, oxidation, and any organic growth without attacking the roof's coating.

Why drone cleaning works well for metal roofs:

Metal roofs, particularly those with steep pitches or smooth profiles, can be extremely slippery,especially when wet. This makes them dangerous to walk on, even for experienced professionals.

Drone cleaning removes this safety risk entirely while ensuring complete, even coverage across the entire roof surface. The aerial perspective also allows the operator to identify any areas of concern, such as early rust spots or lifting flashings.

Asphalt Shingles

Where you'll find them: Older homes throughout Auckland, particularly in established suburbs like Mt Eden, Epsom, Remuera, and across the North Shore.

Asphalt shingles have been used in New Zealand for over 40 years. They're affordable, come in various styles, and provide good weather protection when properly maintained.

However, they're also one of the most easily damaged roof types when it comes to cleaning.

The Problem with Asphalt Shingles

Asphalt shingles have a layer of mineral granules embedded in their surface. These granules serve several important functions:

• Protecting the asphalt from UV radiation
• Providing fire resistance
• Adding weight to keep shingles in place
• Creating the shingle's colour and appearance

The problem? These granules can be dislodged, and once they're gone, they're gone forever.

Asphalt shingles are also highly prone to algae growth, particularly a type called Gloeocapsa magma. This algae creates the distinctive dark streaks you'll often see on shingle roofs. Beyond being unsightly, this algae feeds on the limestone filler in shingles, gradually degrading the material.

How to Clean Asphalt Shingles (The Right Way)

Absolutely never pressure wash asphalt shingles.

This cannot be emphasised strongly enough. High-pressure washing will strip granules from your shingles, dramatically shortening their lifespan and voiding most warranties. A single aggressive pressure washing can cause more damage than years of normal weathering.

Soft washing is the only appropriate method.

The cleaning solution, typically a sodium hypochlorite-based product diluted to safe concentrations, does all the heavy lifting. It kills algae, moss, and other organic growth without any mechanical action that could dislodge granules.

The solution is applied at very low pressure (no more than a garden hose) and left to work. Dead algae and moss gradually wash away over the following weeks with natural rainfall.

Critical considerations:

• The cleaning solution must be properly diluted to avoid damaging the shingles
• Surrounding plants and gardens need protection from runoff
• Gutters should be checked and cleaned after treatment
• Results improve over several weeks as dead growth washes away

Why drone cleaning is perfect for asphalt shingles:

Walking on asphalt shingles, especially older ones, risks breaking the seal between shingles and can dislodge granules with every step. The risk of damage increases significantly on warm days when the asphalt becomes soft.

Drone application eliminates all foot traffic, applying the treatment solution evenly across the entire roof without anyone ever touching the shingles. This zero-contact approach is the safest possible method for this delicate roofing material.

Decramastic Tiles

Where you'll find them: Homes built or renovated in the 1970s and 1980s, scattered throughout Auckland's established suburbs.

Decramastic tiles (also known as pressed metal tiles) were extremely popular during their era. They're lightweight, have a distinctive appearance, and were marketed as a modern alternative to traditional roofing materials.

Unfortunately, they're also notoriously fragile,especially after 40+ years of Auckland weather.

The Problem with Decramastic Tiles

Decramastic tiles consist of pressed steel with a coating of stone chips bonded to the surface with bitumen. Over the decades, this bitumen becomes brittle, the stone chips loosen, and the underlying steel becomes vulnerable to rust.

The tiles themselves become incredibly fragile with age. Walking on a Decramastic roof without extreme care almost guarantees cracked and broken tiles. Even tiles that don't break immediately may develop stress fractures that lead to problems later.

Adding to the challenge, replacement tiles are becoming increasingly difficult to source as the material is no longer manufactured.

How to Clean Decramastic Tiles (The Right Way)

Professional cleaning only,never attempt DIY.

Decramastic roofs require the gentlest possible approach and should only be cleaned by professionals who understand the material's limitations.

Key requirements:

• Ultra-low pressure application only
• No walking on the roof surface whatsoever
• Appropriate cleaning solutions that won't attack the bitumen coating
• Careful attention to the condition of each tile during cleaning
• Honest assessment of whether cleaning is appropriate given the roof's condition

In some cases, a Decramastic roof may be too deteriorated for cleaning to be worthwhile. A professional should assess the roof's condition and advise whether cleaning will extend its life or whether replacement should be considered.

Why drone cleaning is essential for Decramastic:

For Decramastic roofs, drone cleaning isn't just preferable,it's really the only sensible option.

Zero foot traffic means zero risk of cracking these fragile tiles. The drone can apply treatment solution gently and evenly across the entire surface while the operator monitors the roof's condition via camera.

Any areas of concern,loose tiles, visible rust. Damaged sections,can be identified during the cleaning process and reported to the homeowner for follow-up repair.

The Common Thread: Soft Wash Wins Every Time

Regardless of your roof type, one thing is clear: aggressive high-pressure cleaning does more harm than good.

Modern soft wash techniques use cleaning chemistry rather than brute force to achieve superior results. The treatment kills organic growth at the root level, provides longer-lasting results than pressure washing, and protects your roofing materials rather than damaging them.

When combined with drone application technology, soft washing becomes even more effective. Complete coverage is achieved without any foot traffic, protecting your roof from both the growth that was harming it and the potential damage from traditional cleaning methods.

Not Sure What Roof Type You Have?

Many Auckland homeowners aren't certain exactly what material their roof is made from,especially if they've recently purchased the property or if the roof was installed before their time.

If you're unsure, a professional assessment can identify your roof type and its current condition, then recommend the appropriate cleaning approach.

Different sections of some roofs may even have different materials,it's not uncommon to find a metal garage roof attached to a house with concrete tiles, or an extension with different roofing to the original structure.

Protect Your Roof the Right Way

Your roof is designed to protect your home for decades, but only if you protect it in return. Using the wrong cleaning method can undo years of good service in a single afternoon.

The key takeaways:

• Know your roof type before any cleaning takes place
• Always choose soft wash over high-pressure methods
• Avoid foot traffic wherever possible to prevent physical damage
• Use appropriate chemicals formulated for your specific roofing material
• Work with professionals who understand Auckland's diverse roofing landscape