For most Auckland homes, every two to three years. That's our general advice for a roof clean or treatment, and it fits the majority of roofs we see.
But a roof under a big tree in Titirangi and a long-run iron roof on a sunny section in Manukau are not the same. Here's how to work out what yours needs.
Why Auckland roofs grow moss and lichen
Warm, humid air and plenty of rain make Auckland a great place for things to grow, including on your roof. Moss likes damp and shade. Lichen, those grey, white and orange crusty patches, will grow almost anywhere it can get a grip.
Concrete tiles and chip-coated roofs like Decramastic have a rough surface that holds spores and moisture. Long-run iron is smoother but still gets lichen, especially on older, chalky paint. The south side of the roof and any part shaded by trees or a neighbouring house will always grow first.
What affects how often you need it
Shade and trees
The single biggest factor. Roofs under trees or near native bush stay damp longer and get a steady supply of leaf litter. West Auckland homes near the Waitākere Ranges, North Shore homes backing onto reserves and anywhere with large trees overhead tend to need attention more often.
Which way it faces
South-facing slopes get the least sun. On many roofs the north side looks fine while the south side is green.
Roof type and age
Old concrete tiles that have lost their surface coating grow moss fast. Chip-coated roofs hold growth in the texture. Newer iron roofs with sound paint stay cleaner for longer.
Coastal or inland
Coastal homes get salt build-up as well as growth, which dulls the roof and is hard on metal fixings.
Signs your roof needs attention
Have a look from the street or the far side of the section:
- Green or dark patches, especially on the south side
- Spots of grey, white or orange lichen
- Moss building up along tile joins or in the valleys
- Gutters filling up with moss and grit
- Black streaks running down the roof or the walls below
- A roof that just looks dull and tired compared with the neighbours
What happens if you leave it too long
Moss acts like a sponge. It holds water against the roof long after the rain stops. On tiled roofs it can build up between tiles and push water sideways, under laps and toward the roof space. Washed into the gutters, it causes blockages and overflows.
Lichen roots into the surface coating. The longer it's there, the harder it is to remove, and if you want to repaint the roof later, every bit has to go first.
Leaving it doesn't usually cause a sudden failure. It just shortens the life of the roof bit by bit and makes the eventual fix bigger. House insurance generally won't cover roof cleaning either, since it's maintenance.
Clean or treat?
These are two different jobs, and the right one depends on your timeline.
Roof cleaning washes the growth off on the day. It's an instant result. It's the one to choose before painting, before selling, or when the moss is thick. Find out more on our roof cleaning Auckland page.
Roof treatment is spray and leave. The treatment kills moss and lichen down to the roots over about four to six weeks, then the dead growth weathers away over eight to twelve months. It's slower but usually cheaper, and great for keeping a roof clean once it's in good shape. See our roof treatment Auckland page.
Many people do both. Clean the roof once to get it back to a good state, then treat it every couple of years to keep it there.
A simple schedule
| Roof situation | Suggested timing |
|---|---|
| Sunny, newer iron roof | Check every 2 to 3 years |
| Average tiled roof in the suburbs | Clean or treat every 2 to 3 years |
| Shaded, under trees or near bush | Every 1 to 2 years |
| About to paint or sell | Clean just before |
Can you clean it yourself?
We'd steer you away from it. Roofs covered in wet moss are slippery, and a fall from roof height is serious. A water blaster in the wrong hands strips the chip off Decramastic and can crack old tiles. Treatment products need careful handling around gardens and water tanks.
If you want to do something yourself, keep the gutters clear and trim back branches overhanging the roof. Both slow down regrowth. The moss and grit that comes off the roof ends up in the spouting, so book a gutter clean in Auckland at the same time if yours are full.
Getting a quote
Roof prices depend on size, pitch, roof type and how much growth there is. We'll give you a free quote first. Call us on 027 303 8398, seven days, 7am to 7pm.
Roof cleaning questions
How often should I clean my roof in Auckland?
Every two to three years for most roofs. Shaded roofs or those under trees may need it every year or two.
Will cleaning damage my roof?
Not when it's done right. We use methods that suit the roof type, with more care on chip-coated and older tiled roofs.
How long does a roof clean take?
Anywhere from a few hours to a full day, depending on the size and condition of the roof.
Does house insurance cover roof cleaning?
Usually not. It's treated as maintenance. Check with your insurer if you're unsure.