If you have looked up at your roof lately and noticed it has gone a bit green or black, you are looking at moss and algae growth. In Auckland’s climate, this is extremely common. It is also something worth dealing with before it becomes a bigger problem.
Why does moss grow on Auckland roofs?
Moss loves moisture, shade and organic debris. Auckland has all three in abundance. The wetter western and southern suburbs tend to see moss build up faster. North-facing roofs get more sun and generally fare better. South-facing roofs, especially those near trees, can go green in under a year.
What does moss actually do to your roof?
- It holds moisture against the roofing material, which accelerates corrosion on metal roofs and degrades concrete tiles
- It gets under tiles and ridges as it grows, lifting the edges and creating entry points for water
- On iron and steel roofs, trapped moisture speeds up rusting significantly
- It feeds on roofing material in the case of concrete tiles, slowly breaking down the surface
A roof that has been neglected for five or more years can need partial re-roofing in areas that only needed a simple treatment at the two or three year mark.
What is involved in a roof treatment?
We use a soft wash approach rather than high-pressure blasting. High pressure on a roof can displace pointing on ridges, remove granules from tiles, and force water under the roofline. Low pressure with a biodegradable solution is safer and just as effective.
After the wash, we apply a moss inhibitor. Without it, you will have moss back within 12 months. With treatment, you are typically looking at two to three years before it becomes an issue again.
We treated a home in Howick that had been ignored for seven years. The moss was thick on the south slope. It came off, and the roof was in better shape than the owner expected. But the pointing on several ridges needed repair that could have been avoided with earlier treatments.
What does it cost?
A roof treatment for a standard three-bedroom Auckland home typically starts from $300. We will give you an accurate quote after seeing it.