Get the lawn off your roof.
We treat moss, lichen and algae with a low-pressure soft wash, then let the weather carry the dead stuff away over the months that follow. No blaster anywhere near your tiles or iron.
Your roof's got squatters.
Moss, lichen and algae move in wherever a roof stays damp and doesn't see much sun. Our damp coastal air gives them a fair bit of help.
Moss is the green, spongy stuff. It settles in on the shady side and anywhere leaves and grit pile up.
Lichen is the crusty grey, white or orange spots that look like someone flicked paint at your roof. It grips tight and doesn't let go in a hurry.
Algae is the dark streaking and green film. Less dramatic, but it makes a roof look tired, and a wet, grubby roof is a slippery one.
None of it belongs up there. The trick is getting rid of it without hurting the roof underneath.
Water blast a roof? Yeah, nah.
A blaster rips the growth off fast. Trouble is, it can rip bits of your roof off with it.
Quick on the day. Costly later.
- On Decramastic and other stone-chip tiles, it's low pressure or nothing. A hard jet can strip the stone chips for good, and the bare steel left behind can start rusting within months.
- Concrete and clay tiles can crack under a hard jet.
- Water can be forced up under the laps and joins of a steel roof. The steel roofing code of practice says to keep any jet away from laps and openings for exactly that reason.
- On roofing that contains asbestos, it's banned outright. WorkSafe says high-pressure water blasting must not be used on it.
Treat it, then let the weather finish.
- The treatment goes on at low pressure as a soaking spray, working from the top of the roof down.
- It goes after the moss, lichen and algae where they're growing, instead of trying to tear them off.
- The dead growth weathers off over the following months, with far less risk to your coating and tiles.
- It's the approach WorkSafe points to as the safe alternative on asbestos-cement roofing.
Sources: WorkSafe, high-pressure blasting and asbestos roofing, the NZ Metal Roofing Manufacturers code of practice on washing and trade guidance on Decramastic
Different roof, different rules.
Long-run steel
COLORSTEEL and the other pre-painted steel roofs. The coating is the bit that matters, and the steel roofing code of practice warns that harsh cleaners, solvents and abrasives can damage it. The code sticks to a hose, a soft brush and mild detergent, or controlled low-pressure washing aimed away from the laps.
Unpainted zinc and aluminium coated steel gets the same gentle handling. Hard scrubbing can strip its protective film.
Pressed metal tile and Decramastic
Steel tiles with a stone-chip coating. Once the chips come off, they don't go back on, and bare steel is left to rust. So it's low pressure only. Some older Decramastic can also contain asbestos, more on that below.
Concrete tile
Strong if you step in the right spot, over the batten. The overlapping side edges are where they crack, and wet tiles are slippery.
Clay tile
More brittle than concrete. Same careful footwork, and some clay roofs are better treated without walking on them at all.
Older cement roof? Let's talk first.
Corrugated cement roofing, often called Super Six or Super Eight, was generally put on before the mid-1980s and can contain asbestos. So can some older Decramastic. There's no telling by eye. The only way to know is a sample tested by an accredited lab, so an older roof may need testing before anyone goes near it with water.
WorkSafe is clear on one thing: no high-pressure water blasting on roofing that contains asbestos, and anything over 50 PSI counts as high pressure. Breaking that rule can mean fines of up to $30,000.
Confirm: what you do with a roof that might contain asbestos, for example ask for a lab test first, soft wash with a set PPE routine, or pass on the job
Source: WorkSafe, high-pressure water blasting and asbestos roofing
It won't look clean the day we leave.
Roof treatment isn't a magic eraser. The treatment does its work on the growth, then the weather does the slow bit. Here's roughly how it plays out.
Treatment day
The treatment goes on at low pressure. When we pack up, your roof will look much the same, maybe a bit blotchy. That's normal.
The first month or so
The growth dies back. Trade guidance puts that at roughly 4 to 6 weeks, and the roof can look patchy or discoloured while it happens.
The months after
Rain and wind wash the dead growth off bit by bit. You'll often see it breaking down within two or three months, and clearing completely can take 8 to 12, depending on the product, the pitch and how much was up there.
These are trade figures and they vary between operators and products, so take them as a rough guide, not a promise. Confirm: the timeframe your treatment product states
Placeholder: shoot the same roof from the same spot on treatment day and again a few months later, and they drop in here.
Downpipes off before we start.
If your roof feeds a rainwater tank, the downpipes into it need to be disconnected or diverted before any treatment goes on. Roof treatments aren't meant to end up in your drinking water.
They stay off until a decent amount of rain has flushed the roof. Trade guidance from one NZ roof cleaner is at least 30mm of follow-up rain before reconnecting. The steel roofing code of practice makes a similar call: wash with detergent where the runoff feeds drinking water, and the roof outlets need disconnecting first.
Confirm: your tank-water routine, including who disconnects and reconnects the downpipes, how much rain you wait for, and whether you come back to reconnect
Source: NZ Metal Roofing Manufacturers code of practice, washing
What the roof makers say.
NZ steel roof makers want their roofs washed, and they're particular about the bits the rain never reaches.
New Zealand Steel's COLORSTEEL warranty guidance says areas under eaves, around gutters and beneath fixtures miss out on natural rain-washing, so they need regular manual cleaning. It also says the maintenance programme has to be followed to keep the warranty valid, and COLORSTEEL's own warranty terms ask for a record of when it's done.
Dimond says roofs should be washed regularly with clean water, with extra attention to spots that get little rain, and that coastal homes may need it more often to shift salt.
Washing those sheltered spots is a different job from treating moss. Confirm: do you wash the unwashed areas on steel roofs, and give owners a dated record for their warranty file?
The fine print varies by maker and by product, so check your own roof's warranty terms. If you know the brand and profile, pop it in the quote form.
Sources: COLORSTEEL warranty maintenance, Dimond, maintaining your roof and the NZ Metal Roofing Manufacturers code of practice
How often to hand wash, by environment
- Mild: natural rain does the washing.
- Moderate: a manual wash every year.
- Severe: every 6 months.
- Very severe: every 3 months.
- Extremely severe: every month.
Which band your roof sits in depends on its environment, and COLORSTEEL's guide sets that out. Other makers have their own versions.
Your bit's quick. The roof takes its time.
Tell us about it You
Fill in the form with your address, and mention your roof type and whether you're on tank water if you know. Both change how we go about it.
Check and prep
We confirm what the roof's made of, wait for a dry day without much wind, and sort the downpipes if you're on tank water. Confirm: whether you clear valley and gutter debris first, and how you protect plants below
Treat, then wait
The treatment goes on at low pressure, from the top of the roof down. Then the weather takes over, and the dead growth washes away over the following months.
Roof questions, answered straight.
How long until the moss and lichen are gone?
Will water blasting damage my roof?
Will treating my roof affect its warranty?
I'm on tank water. Can my roof still be treated?
Could my roof have asbestos in it?
Do you walk on tile roofs?
How often does a roof need treating?
Can you guarantee the moss won't come back?
Will it hurt my garden?
Should I get my gutters done too?
How much does it cost?
Make it a full spruce-up.
Let's get your house juicy.
Tell us where you are and what needs a wash. We'll come back to you with a price.
Rather talk? Call 021 000 0000 or email hello@juicyhousewash.co.nz.
Sweet, it's in.
We'll be in touch with your quote soon.