Moss vs lichen
Lichen is the flat, crusty growth, often grey, yellow or orange. It's mainly a cosmetic issue, though it's worth clearing if it builds up in valleys.
Moss is the green, spongy growth. It soaks up water and holds it against the tiles, and as clumps come loose they block valleys and gutters. That's how moss leads to leaks.
Why Auckland roofs get so much moss
Auckland's mild, damp climate is ideal for it. It grows fastest on the south side of the roof, under trees, and on older tiles whose surface has become rough and porous.
Don't water-blast
High-pressure cleaning can strip the surface of older concrete and clay tiles and push water past the tiles, especially on older roofs that may not have underlay. Consumer NZ advises against using a high-pressure water blaster on tile roofs.
How we treat it
We apply a moss and lichen treatment to the roof. It kills the growth, which then breaks down and washes off gradually with the rain over the following weeks and months. Where moss is blocking valleys, we clear it by hand. Moss treatment starts from $250 + GST.
Keeping it away
- Trim branches overhanging the roof
- Keep gutters and valleys clear
- Re-treat when growth starts to come back, often every few years
Rainwater tank? Tell your roofer before any moss treatment. You'll need to disconnect the tank during treatment and for a period after.