Roof Moss, Lichen & Mould Removal in Brisbane

Black or dark brown streaks are almost always algae rather than mould. They are caused by Gloeocapsa magma, a blue-green algae that grows a dark coating as it spreads. Moss is the soft green build-up in the tile grooves, and lichen is the crusty grey-green patches gripping the surface. Many Brisbane roofs have all three, and one soft wash treats them together.

Lichen is treated with a soft wash. A biodegradable treatment is sprayed on at low pressure and left to sit, so it kills the lichen at the root. The roof is then rinsed gently. Scraping or high pressure is not used on terracotta tiles or COLORBOND®, because it can crack tiles and strip coatings. The roof condition is checked before any treatment goes on.

A pressure clean removes the growth you can see but leaves living spores and roots behind. An untreated roof can then stain again within a year or two. High pressure on terracotta tiles or coated metal can also crack tiles and strip the protective coating. Working on a wet roof is where serious falls happen, so it is a job for someone harnessed and insured.

It varies with the roof, the direction it faces and the trees around it. Many Brisbane roofs stay clean for two to four years after a soft wash. Shaded, tree-lined and bayside roofs, where moisture hangs around, tend to see growth return sooner. Nothing stops it for good, because the spores are always in the air, but killing the growth at the root slows the regrowth.

The treatment is biodegradable and breaks down after it is applied. Keep pets inside while it is on the roof and during the rinse. If your home is on a rainwater tank, tell us when you enquire so the tank can be isolated or diverted during the clean. Gardens and plants are worked around, and the run-off, the water that drains off the roof, is managed on every job.

It is priced per roof rather than as a flat rate. The cost depends on the roof size, its pitch (how steep it is), the material, access and how much growth has built up. After a free roof assessment you get a clear, upfront quote, so you know the price before any work starts.

The cooler, drier months from April to September suit the work well, because the growth is spreading more slowly and the roof dries faster afterwards. Roofs are cleaned all year round in Brisbane, though. If the growth is already heavy heading into the wet season, it is worth booking now rather than waiting.

Brisbane's warm, humid weather keeps roofs damp for much of the year, which is what moss, lichen and algae need. The shaded side of a roof, usually the south-facing side, dries out slowest. Overhanging trees keep it damp and drop debris that feeds the moss. Our guide on why Brisbane roofs grow moss and black algae goes through the causes.