What Is Roof Moss Treatment?
Ever looked up and wondered when your roof turned green and black? In Rotorua, it happens faster than most people expect.
Roof moss treatment removes the moss, mould and lichen that build up on your roof over time. According to weather-and-climate.com, Rotorua gets about 1,389 mm of rain a year. Add shaded sections and lake-edge humidity, and roofs stay damp for long stretches. That’s exactly what moss and lichen need.
If you own a rental, a taller house or a multi-level building, getting up there yourself isn’t worth the risk. That’s where we come in.
We use soft wash technology: a low-pressure rinse delivered with clean hot water. It lifts growth off the surface without the brute force of cold-water high-pressure blasting. High pressure can:
- Strip coatings
- Crack tiles
- Push water under the laps of your roofing
Why Does Moss and Lichen Matter?
Each type of growth harms your roof in its own way. Here’s what we see most often around Rotorua:
- Moss works like a sponge. It holds water against the roof surface long after the rain stops, which breaks down paint and coatings and keeps fixings wet.
- Lichen is slower but tougher. Its thallus sits on the surface while tiny rhizoids grip into it.
- Black algae causes the dark streaking on many roofs. It’s often Gloeocapsa magma, which feeds on moisture and minerals and spreads across shaded faces. Strictly speaking, it’s a cyanobacterium rather than a true alga, but most people call it algae.
On Decramastic tiles, lichen can mean chip loss over time. Promain Roofing, a New Zealand roof painting company, says moss and lichen erode Decramastic roof paint. Left alone, bare metal can show through and start to rust.
All of it ends up in your spouting eventually. Clumps of moss and grit wash down with every downpour and block the outlets.
That’s why we finish every roof treatment with vacuum gutter clearing and a full downpipe flush. If you’re weighing up how urgent your moss is, our guide Is moss damaging my roof? walks through the warning signs.
Which Roofs Can We Treat?
We treat the three most common roof types around Rotorua. Each one needs a slightly different touch.
| Roof type | Risk from high pressure | How our soft wash helps |
|---|---|---|
| Longrun iron and Colorsteel | Scours the paint finish | Cleans the ribs and laps without scouring the finish |
| Concrete tiles | Cracking risk on porous tiles | Cleans the surface and laps without the cracking risk |
| Decramastic tiles | Can strip the stone-chip coating | A gentle method designed for stone-chip roofs |
Longrun iron and Colorsteel
Longrun corrugated iron and Colorsteel roofing are common across Rotorua. A low-pressure hot-water wash cleans the ribs and laps without scouring the paint finish.
Resene’s roofing guides say a Colorsteel roof in good condition mostly needs a thorough wash. Gentle cleaning protects the finish you already have.
Concrete tiles
Concrete roof tiles are porous, and moss loves them. Soft washing cleans the surface and the laps between tiles without the cracking risk that comes with high pressure.
Decramastic tiles
Decramastic tiles have a stone-chip coating that high pressure can strip. Our gentle method is designed for exactly this kind of roof.
If you’re planning to paint the roof afterwards, a clean surface matters. Talk to your painter about roof coating and paint compatibility, such as the Resene system they plan to use. Resene’s roof painting guides call for moss and mould to be treated with their Moss & Mould Killer before painting, so it pays to check the order of work.
We’ll fit the treatment around your painter’s timing.
Tank Water and Moss Inhibitor
Do you collect rainwater? Then your tank needs protecting while we work.
On properties that collect rainwater, we disconnect the tank downpipes before we start. Once the roof has been rinsed, we reconnect them. Kiwicare, the New Zealand outdoor cleaning brand, gives the same advice for any roof that feeds a tank: disconnect during cleaning and rinse thoroughly before reconnecting.
If you’d like to talk about a moss inhibitor to slow regrowth, we can discuss what suits your roof at the free quote. Whether you own a rental, a two-storey home or a multi-level building, the next step with your roof moss treatment is easy. Book your free quote and we’ll take a look.
