Those crusty grey-green patches spreading across your roof tiles aren’t dirt, and they won’t wash off in the next storm. That’s lichen — and if you’ve noticed it on your Brisbane roof, it’s been there longer than you think.
If you want the short answer on how to get rid of lichen on your roof: you have to kill it at the root with a dwelling treatment solution, then rinse it away at low pressure. You cannot scrub it, scrape it or blast it off. Lichen anchors itself into the tile, so anything that only removes what you can see leaves the roots behind — and it grows straight back, usually within months.
This guide covers the method that works, the four DIY approaches that make things worse, how the treatment changes depending on whether you’ve got terracotta, concrete or Colorbond, and how to keep lichen off the roof once it’s gone.
Table of Contents:
First, what is lichen — and why is it so hard to remove?
Lichen isn’t a plant and it isn’t quite a fungus. It’s a partnership between the two — a fungus and an algae living together as a single organism. The algae photosynthesises and produces food; the fungus provides structure and grips the surface it’s growing on.
That grip is the problem.
Unlike moss, which sits on top of a surface and can be brushed away, lichen anchors itself. It sends root-like structures called rhizines down into the microscopic pores of your roof tiles. On terracotta and concrete tiles, those pores are everywhere. Lichen doesn’t sit on your roof — it grows into it.
You’ll recognise it by the raised, crusty, circular patches, usually pale grey-green or sometimes a dull orange, with a slightly ruffled edge. Moss, by contrast, is soft, green and velvety, and tends to gather in valleys and along tile overlaps.
Most Brisbane roofs have both. They thrive in the same conditions and are almost always treated together.
How NOT to get rid of lichen: 4 methods that make it worse
We get called out to plenty of roofs where the homeowner has already had a go. Here’s what typically happens.
Pressure washing. This is the big one. A high-pressure wash will blast lichen off — along with the protective surface coating of your tiles, the granules on any coated surface, and sometimes the tiles themselves. It also drives water up under tile overlaps and into the roof cavity. The roof looks clean for a season. Then the lichen returns faster than before, because the surface is now more porous than it was to start with. On terracotta and older concrete tiles, high pressure does real, permanent damage.
Scrubbing or scraping. Because lichen is anchored into the tile, mechanical removal takes the surface with it. You’ll also leave the rhizines behind, which means regrowth within months.
Bleach and household cleaners. Chlorine bleach will kill surface growth and lighten the stain, which makes it look like it worked. It doesn’t penetrate to kill the organism at the root, it damages roof coatings and metal fixings over time, and the run-off kills the garden beds and lawn below. This is the most common question we get — and the honest answer is that bleach treats the symptom, not the cause.
Walking on the roof. Beyond the risk to you, tiles crack under foot pressure, particularly older terracotta. A cracked tile you didn’t notice is a leak next storm season. Roof work in Queensland at height carries genuine safety and licensing requirements for good reason.
How to get rid of lichen on your roof: the method that works
Effective lichen removal comes down to one principle: kill the organism at the root, then remove it gently. Get that order wrong and you’re just moving it around.
The method we use across Brisbane and SE-QLD is soft washing.
Step 1 — Inspection and preparation. Before anything else, the roof gets assessed for cracked or slipped tiles, deteriorated pointing and problem areas. Gardens, downpipes and sensitive surfaces are protected.
Step 2 — Treatment application. A biodegradable cleaning solution is applied across the roof and left to dwell. This is the part that matters — the solution penetrates the lichen and kills it at the root, including the rhizines embedded in the tile. Nothing is being scraped or blasted at this stage.
Step 3 — Low-pressure rinse. Once the treatment has done its work, the dead growth is rinsed away at low pressure — roughly the force of a garden hose, not a pressure washer. The lichen comes away because it’s dead and no longer anchored, not because it’s being forced off.
Step 4 — Clean-up and check. Gutters and downpipes are cleared of the debris that’s come down, and the roof is re-checked.
The difference in results is the regrowth timeline. A pressure clean might buy you a year. A properly treated soft wash roof stays clear for considerably longer, because the organism was actually killed rather than knocked off.
How to remove lichen from different roof types
The soft wash principle stays the same, but the solution strength and technique are adjusted for the surface you’re working on.
Terracotta tiles. The most vulnerable to high pressure and the most prone to heavy lichen once the glaze has worn. Soft wash only. After cleaning, terracotta often benefits from a re-seal to slow future growth.
Concrete tiles. Porous and a very common lichen host across Brisbane. These clean up well, and cleaning is the necessary first step if you’re considering a roof paint or restoration — no coating bonds properly to a contaminated surface.
Colorbond and metal. More resistant, but not immune. The critical point here is that the wrong chemical or too much pressure will damage the factory coating and void manufacturer warranty. Colorbond needs a manufacturer-approved cleaning method, not a generic roof wash.
Painted or coated roofs. The existing coating has to be preserved. Soft washing is the only sensible option — pressure cleaning strips coatings and you’ll be repainting far sooner than planned.
Why Brisbane roofs get lichen so badly
South East Queensland is close to a perfect environment for lichen. Three factors drive it:
Humidity and rainfall. Brisbane’s subtropical climate delivers warm, humid conditions for most of the year, plus a summer storm season that keeps roof surfaces damp for extended periods. Lichen needs moisture to establish, and it gets plenty.
Shade. Roofs under mature trees, or on the southern side of a two-storey home, dry out slowly after rain. Those areas grow lichen first and worst. If you’ve got jacarandas, gums or poincianas overhanging the roofline, expect the growth directly beneath them to be significantly heavier.
Porous roof surfaces. Concrete and terracotta tiles are naturally porous, and that porosity increases as the protective glaze or coating wears away with age. An unpainted or unsealed tile roof over 15 years old is essentially an ideal growing surface. Colorbond and metal roofs are far more resistant, but not immune — lichen will still take hold in areas that stay damp, particularly along low-pitch sections and around fixings.
Add falling leaves and organic debris to any of the above and you’re feeding the growth as well as watering it.
Is lichen on your roof actually a problem?
Yes — for four reasons that get progressively more expensive.
1. It damages the tile surface. Those rhizines burrow into the tile. As lichen grows and expands, it widens micro-cracks and lifts the surface material. Over years, this erodes the protective outer layer of concrete and terracotta tiles, leaving them more porous — which accelerates the next round of growth. It’s a cycle that gets worse, not one that plateaus.
2. It holds moisture against your roof. A lichen colony acts like a sponge. Instead of your roof drying out after rain, sections of it stay wet for days. Persistent moisture against tiles and mortar is what leads to deteriorated bedding and pointing, and eventually to leaks.
3. It blocks water flow and clogs gutters. Heavy growth disrupts the way water sheds off your roof, pushing it sideways under tile overlaps rather than straight down. Pieces of lichen and moss also break off and wash into your gutters, where they combine with leaf litter to create blockages. During a Brisbane downpour, a blocked gutter overflows — usually into your eaves or down your walls.
4. It makes your roof hotter and your home look neglected. A dirty, lichen-covered roof absorbs more heat than a clean one, which flows through to your indoor temperature and cooling costs. And from the kerb, it’s the single fastest way for a well-maintained home to look run-down. If you’re preparing to sell, it’s one of the highest-return cosmetic fixes available.
How to stop lichen coming back after removal
Once the roof is clean, a few things meaningfully slow the return:
- Cut back overhanging branches. More sunlight and airflow on the roof means faster drying and dramatically less growth. This is the highest-impact thing most homeowners can do.
- Keep gutters clear. Debris-packed gutters hold moisture right at the roof edge and seed regrowth. Twice a year is a reasonable schedule in Brisbane, more if you’re under heavy tree cover.
- Consider sealing or painting. A sealed or freshly painted roof presents a non-porous surface that lichen struggles to grip. This is why roof cleaning and roof painting are so often done together — the clean is required for the paint, and the paint extends the life of the clean.
- Clean on a cycle, not a crisis. A maintenance wash every two to three years costs a fraction of what it takes to deal with a decade of accumulated growth and the tile damage underneath it.
When it’s time to call someone
Book a professional clean if any of the following apply:
- Growth covers a significant portion of the roof rather than isolated patches
- Your roof is two-storey, steep, or otherwise not safely accessible
- Tiles are already cracked, slipped or have deteriorated pointing
- It’s a Colorbond or coated roof where the wrong method risks the warranty
- You’ve pressure cleaned before and it came straight back
- You’re planning to paint, restore or sell
Get lichen removed properly — Brisbane & SE-QLD
Apex Roof Painting are soft wash specialists servicing Brisbane, the Gold Coast, the Sunshine Coast and surrounding South East Queensland suburbs. We treat lichen, moss, mould and algae at the root using biodegradable solutions that are safe on tile, terracotta and Colorbond — no high-pressure damage to your roof.
Every job includes a free on-site inspection and a fixed-price quote, and all our work is backed by a written guarantee. We’re fully insured with $20M public liability and licensed to work at heights up to 20m.
[Get a Free Quote] — or call us today for a no-obligation inspection.
FAQ SECTION
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How do you get rid of lichen on a roof permanently? The only way to get rid of lichen on your roof permanently is to kill it at the root. A biodegradable treatment solution applied and left to dwell does this, including the rhizines anchored into the tile. This is what prevents rapid regrowth. Scrubbing, scraping or pressure washing removes only the visible growth and leaves the anchoring structures behind, so it returns within months.
Does bleach kill lichen on a roof? Chlorine bleach kills surface growth and lightens staining, so it appears to work — but it doesn’t penetrate deep enough to kill the organism at the root. It also degrades roof coatings and metal fixings over time, and the run-off damages surrounding gardens and lawn. Professional treatment solutions are more effective and safer for the roof and your property.
Can I pressure clean lichen off my roof? You can, but it’s the most common cause of roof damage we see. High pressure strips the protective surface from concrete and terracotta tiles, forces water under tile overlaps into the roof cavity, and can crack tiles outright. It also leaves the tile more porous than before, so the lichen returns faster. Soft washing achieves better results without the damage.
How much does roof lichen removal cost in Brisbane? Cost depends on roof size, roof type, pitch, access and how heavy the growth is. As a general guide, professional roof cleaning in Brisbane typically ranges from around $600 to $1,200 + GST for a standard residential roof. We provide a free measure and fixed-price quote before any work starts. [Verify pricing against current Apex rate card before publishing]
How often should a Brisbane roof be cleaned? Every two to three years suits most SE-QLD homes. Roofs under heavy tree cover, in shaded positions or in higher-humidity coastal areas may need attention more frequently.
Is lichen on a roof dangerous? Not directly to your health, but it damages the roof. Lichen erodes the tile surface, holds moisture against the roof structure, contributes to deteriorated pointing and leaks, and blocks gutters. It also makes roof surfaces extremely slippery, which is a genuine safety hazard for anyone getting up there.
Will lichen come back after cleaning? Eventually, yes — it’s a natural process in a subtropical climate. But a properly treated soft wash keeps a roof clear far longer than a pressure clean. Trimming overhanging branches, keeping gutters clear and sealing or painting the roof all extend the result significantly.