What builds up on Tauranga roofs, and why
Mild and often damp
Low-lying coastal Tauranga has a mean annual temperature of around 14°C, and the airport records 151 days a year with at least 0.1 mm of rain. Air frosts are rare, at 3.9 a year. Mild, regularly damp conditions like that suit moss and lichen, particularly on south-facing slopes and under trees.
Salt on the seaward side
BRANZ says buildings close to breaking surf need more frequent maintenance, especially washing to remove salt, which matters along the Mount and Pāpāmoa beachfronts. Metal roofing also needs a small amount of ongoing upkeep to keep its warranty, so a gentle wash here is maintenance, not a luxury.
Frosty grass, slippery roof
The airport averages 54.6 ground frosts a year against only 3.9 air frosts, so a winter roof can be slick at first light even when the air never freezes. A roofer starting early on a winter job should treat it like a wet roof.
Plenty of new homes, some older roofs
Tauranga is a young city, but WorkSafe says any house built before 1 January 2000 may contain asbestos, and lists roofing panels such as Super Six and asbestos cement ridge capping among the places it hides. You can't tell by looking, so a roofer should rule it out before any cleaning starts.
What a proper roof clean involves
A moss treatment (a biocide sprayed on to kill moss, lichen and mould) does most of the work, and dead growth often weathers off over the following weeks. A soft wash at low pressure then lifts grime and salt without stripping paint or wearing the surface of concrete tiles. Water-blasting is quicker, but it's harder on a roof and forces water up under laps and flashings if it's done carelessly.
For asbestos cement and decramastic roofs, WorkSafe's safe work sheet is clear: apply biocide with a low-pressure sprayer, keep the surface wet, and never use high-pressure spraying or blasting. A business also must not use water spray over 350 kPa on asbestos at all. If a quote mentions water-blasting an old roof, ask why.
Cleaning is maintenance, so it doesn't need a building consent or an LBP. It does need fall protection: WorkSafe says workers on single-storey homes need the same level of protection as those on two-storey homes.
What makes a roof clean bigger or smaller
Roof size, pitch and height, how thick the moss and lichen are, and whether the spouting gets cleared on the same visit all change the size of the job. Ask for the method, the product and the fall protection to be written into the quote, so you know exactly what you're agreeing to.
Questions to ask before a Tauranga roof clean
- Will you soft wash or water-blast my roof, and why that method for this roof?
- Have you checked whether my roofing or ridge capping could contain asbestos?
- Which moss treatment are you using, and is it safe around my garden and rainwater tank?
- Is clearing the spouting and downpipes afterwards included in the job?
- How will you manage fall risk, and will there be edge protection?
- Will you photograph anything broken or loose you find while you're up there?
Your part, and the roofer's
You can
- Trim branches that shade or overhang the roof, working from the ground
- Look over the roof with binoculars for thick moss, lichen or salt staining
- Rinse salty soffits and overhangs with a garden hose from the ground if you're near the beach
Leave to a roofer
- Applying moss treatment or washing on the roof itself
- Anything on a roof that could be asbestos cement or decramastic
- Two-storey or steep roofs
- Checking and fixing anything loose the clean uncovers
If it were our roof in Tauranga
We'd treat the moss and soft wash rather than blast, and we'd leave a few weeks between the clean and any repaint so the coating has a sound surface to grip. Near the beach, we'd hose the sheltered overhangs from the ground every few months. If you're planning to paint anyway, read roof painting in Tauranga first, because the clean is the first step of that job.
Want a roofer to take a look?
Tell us the job and your postcode. We match it with a Find My Roofer certified roofer who specialises in that kind of work, and they call you to quote. Your number goes to them alone.