Moss and lichen on a Wellington roof is about as common as wind. The question we get asked most is whether the roof needs a proper clean, or whether a spray treatment will do the job.
Both work. They just work differently and suit different situations. Here's how to pick.
Why Wellington roofs go green
Our climate is close to perfect for moss and lichen. Damp winters, lots of shade on hillside sections and plenty of trees all help it along. The south-facing side of a roof, or any roof sitting in the shadow of a hill, usually goes first.
Salt air plays a part near the coast, and the wind blows in leaf litter that sits in valleys and holds moisture. Concrete tiles and chip-coated roofs like Decramastic have a rough surface that gives spores something to grab onto. Long-run iron grows lichen too, mostly as those grey and orange crusty spots.
Left alone, moss holds water against the roof, blocks gutters and valleys, and can work its way under tiles. Lichen roots into the surface coating and makes repainting harder.
The two options
Roof cleaning: a wash for an instant result
A roof clean washes the moss, lichen, dirt and mould off there and then. You see the difference the same day.
It's the right choice when:
- You're painting the roof soon and need a clean surface
- You're selling and want the place looking sharp now
- The growth is heavy, with thick moss or debris built up in valleys
- The gutters are full of what's come off the roof
We use the right method for the roof type. Long-run iron and concrete tiles can handle more pressure. Chip-coated roofs and older tiles need a gentler wash so we don't strip the surface. Details are on our roof cleaning Wellington page.
Roof treatment: spray it and let the weather work
A roof treatment is a spray-and-leave job. We cover the roof with a treatment solution and leave it. Over roughly four to six weeks it soaks into the growth and kills the moss and lichen down to the roots. The dead growth then weathers away gradually over the next eight to twelve months as the rain and wind do their thing.
It's the right choice when:
- The roof has light to moderate growth
- You're not in a hurry for an instant result
- You want to keep a roof clean that's already in good shape
- You'd like a lower-cost option than a full wash
Read more on our roof treatment Wellington page.
Clean vs treat at a glance
| Roof cleaning | Roof treatment | |
|---|---|---|
| How it works | Washed off on the day | Sprayed on, weathers off over months |
| When you see results | Same day | Weeks to months |
| Best for | Heavy growth, pre-paint, pre-sale | Light growth, ongoing upkeep |
| Cost | Quoted per roof | Quoted per roof |
Doing both
Often the best result is a clean followed by a treatment, or a treatment every couple of years after a clean. The wash gets rid of the built-up growth. The treatment stops it coming back as quickly. Our treatment is designed to keep moss and lichen off for around 14 to 18 months.
What to check before you decide
Take a look from the ground, or from a ladder at the gutter line if it's safe:
- What's the roof made of? Iron, concrete tile and chip-coated roofs need different handling.
- How thick is the growth? Thin green film and small lichen spots suit a treatment. Moss you could grab a handful of needs a clean.
- Are you painting soon? If yes, wash it. Paint won't stick properly to dead moss and lichen.
- What are the gutters like? If they're full of moss, they need clearing either way. See our gutter cleaning Wellington page.
- Any damage? Cracked tiles, rust holes or lifting flashings need a roofer, not a cleaner.
Timing in Wellington
Spring and autumn are the best seasons for a treatment. You want a mild spell, not too hot and not too cold, with a few dry days after it goes on. In Wellington that also means picking a day without a gale, so the spray goes where it's meant to.
A roof clean is less fussy about season but still needs a dry, calm day for safety.
Don't DIY on the roof
We know it's tempting to grab a brush and a ladder. But a roof covered in wet moss is slippery, Wellington wind can pick up without warning and many hillside homes have a long drop on the low side. Treatment chemicals also need careful handling around gardens and water tanks. This is a job worth handing over.
Prices depend on the roof size, pitch and how much growth there is. Call us on 027 303 8398 for a free quote. We're open seven days, 7am to 7pm.
Roof moss questions
How often should a Wellington roof be cleaned or treated?
Every two to three years suits most roofs. Shaded roofs and those under trees may need attention sooner.
How long until a treated roof looks clean?
The moss and lichen die off over about four to six weeks, then weather away over eight to twelve months. It's gradual, not instant.
Can moss damage my roof?
Yes. It holds moisture against the roof, blocks gutters and valleys, and can lift tiles. Lichen roots into the surface coating.
Will roof treatment harm my garden?
We take care to protect plants and surroundings, and use eco-friendly products. If you have a water tank collecting off the roof, tell us when you book.