WOLLONGONG MOULD REMOVAL SERVICES
Exterior Mould Removal in Wollongong
Green or black mould on your render, cladding or exterior walls is alive and rooted in the surface. Blast it off with a pressure washer and it grows back by next season. We kill it at the root so it stays gone for years.
Trusted Exterior Mould Removal in the Illawarra, NSW
The south wall’s gone green. The render under the eaves has black streaks running down it. The shady side of the house looks tired and grubby in a way a hose won’t fix. It’s crept up over a couple of wet seasons and now the whole side of the place looks like it needs repainting.
It probably doesn’t. What’s on there is mould, algae and lichen, and it’s living in the surface, not just sitting on it. Clean it properly and the wall underneath is usually fine.
Here’s the part that trips most people up. The instinct is to hire a pressure washer and blast it off. That’s the wrong tool for this job, and it can cost you a re-render. We treat exterior growth the way it actually needs treating, which on render and painted cladding means a soft wash that kills the growth rather than blasting the surface it’s living on.
We’ve been dealing with mould across the Illawarra for 15 years at Wollongong Mould Cleaning & Removal, inside and out. The exterior work is its own thing, and doing it right is mostly about matching the method to the surface.
Is this you?
- Green or black growth on render, painted brick or cladding
- Dark streaks running down from the gutters or under the eaves
- The south or shaded side of the house always looks worse than the rest
- A fence, retaining wall or wall that's gone green and slippery
- You cleaned it once and it came back within months
- You're getting the place ready to sell and the exterior lets it down
FREE INSPECTION, NO OBLIGATION
We will call you back personally to arrange a time.
Soft Washing or Pressure Washing? On Your Walls It Matters
This is where a lot of exterior cleaning goes wrong, and it’s worth two minutes before you hire anyone. Pressure washing uses high-force water to blast dirt off a surface. It’s the right call for hard, tough surfaces where the muck is just sitting on top, like a concrete driveway, pavers or a path. On those, blast away.
BUT your walls are a different story. Render, painted brick, cladding and the like are porous and coated, and two things go wrong when you hit them with high pressure.
- The force erodes the render or strips the paint, and it drives water in behind the coating, which sets up the next problem rather than solving it.
- The one nobody mentions, it doesn’t actually kill the growth. Mould, algae and lichen root down into the surface. Blasting removes the green you can see and leaves the living root behind, so it repopulates and you’re back to a green wall within a season, sometimes worse than before.
Soft washing with a treatment does the opposite. Low pressure, and a biocide that soaks in and kills the growth at the root. Nothing is left alive to grow back, and no force to wreck the finish. That’s why a soft wash on render or cladding holds clean for two to four years, while a pressure blast is often green again by the next wet season. On render it’s also a lot cheaper than the re-render bill if the pressure damages the coating.
So the honest rule is simple. Hard flat ground surfaces can take pressure. Your walls, roof and anything painted or rendered want a soft wash. We use whichever the surface calls for, and on the exterior of a house that’s usually the soft wash.
How We Remove Exterior Mould For Good
First, we match the method to the surface
Render, cladding, painted brick, timber, Colorbond and hard paving all behave differently. We work out what each surface can take before anything gets wet, because getting that wrong is what causes damage.
We treat the growth with a low-pressure soft wash
A biocide solution goes on at low pressure and is given time to work. That dwell time is the bit that matters, it’s what lets the treatment kill the mould, algae and lichen down at the root rather than just wetting the top.
We rinse it down gently
Low-pressure rinse to clear the surface, with care taken around plants, garden beds and run-off. A soft wash done properly protects your landscaping, not just your walls.
We check the cause where there is one
Most exterior growth is just shade, damp and coastal air. But if a blocked gutter, a downpipe or a constant damp spot is feeding it, we’ll point that out, because otherwise the shaded patch comes back faster.
We tell you how to keep it back
Which walls will need doing again and roughly when, and anything simple that slows the regrowth. Straight advice, no upsell and definitely no stitch-ups.
Why the Shady South Wall Always Cops It Worst
If one side of your house is always greener, it’s almost certainly the south or south-east side, and there’s a reason for it.
That side gets the least sun, so it stays damp the longest after rain and dew. Mould and algae need moisture and they hate direct sun, so a wall that never really dries out is exactly where they set up. Add the Illawarra’s coastal humidity and the salt air off the ocean, and the shaded walls here grow a coat of green faster than almost anywhere inland. Anything that sits under trees or a tight eave, holds moisture even longer.
That’s not a fault in your house and it’s not dirt you failed to clean. It’s a surface that’s permanently damp getting the growth you’d expect. The fix isn’t scrubbing harder, it’s killing the growth properly and knowing that side will want doing again sooner than the sunny walls. It’s the same story out in the garden, where timber decks, paling and Colorbond fences, retaining walls, sandstone, pavers and painted pergolas all sit shaded and damp and grow the same green, and they take a soft wash the same way your walls do.
How Much Does Outdoor Mould Removal Cost?
Exterior jobs are priced on size and access rather than a flat rate, so the quote comes after we’ve seen it. The inspection is free.
| What you need | What it covers | Cost |
|---|---|---|
| On-site quote | We look at the surfaces, the access and how far it’s spread, then price it | Free |
| Single wall or section | Soft wash and treatment of one affected wall, fence or shaded section | Quoted on size |
| Full house soft wash | Whole exterior treated, render, cladding, eaves and walls | Quoted on size |
| Two-storey or hard access | Height, tight spaces or difficult ground add to the job | Quoted on access |
What moves the price for this situation:
- The size of the area
- How many surfaces are involved
- Accessibility such as the height, and how hard it is to reach
What you’re really paying for is the growth killed at the root so it stays gone for years, rather than a blast that looks good for a season and takes the finish with it.
Why Local Knowledge Makes the Difference on Illawarra Exteriors
Coastal air here is humid and salty, and that combination feeds exterior growth harder than a drier inland climate ever would.
Basically, walls stay damp, salt sits on the surface, and the shaded sides barely dry out through those cooler months from June – August. It’s why so many homes in the area have one wall that’s permanently green.
We know which surfaces the local homes are built from, from the rendered new builds through to older painted brick and fibro up the northern suburbs, and we know what each can take. We also know which walls are going to need doing again sooner, because we’ve watched how these houses weather. That means you get the right method the first time and an honest read on how long the result will hold.
Straight answers, the right treatment for the surface, and a finish that actually lasts.
Get Your Exterior Looked At
If one side of your house has gone green, the worst thing you can do is take a pressure washer to the render. It’s an expensive mistake. The best thing is to get someone to look at it and treat it properly.
Fill out the form and let us know some details like roughly how big the area is. We’ll tell you what it needs and what it’ll cost after an on-site inspection. Free inspection, no obligation.
Get a Free Inspection Call Now (02) 4093 0541
Frequently Asked Questions
Can I just pressure wash the mould off my walls?
On hard surfaces like a concrete path or driveway, pressure washing is fine.
On render, painted brick or cladding it’s a bad idea.
The high pressure erodes the coating and drives water in behind it, and it doesn’t kill the growth, it only removes what you can see. The root stays in the surface and grows back within a season, so you’ve risked damaging the wall for a result that doesn’t last.
What is soft washing?
Soft washing is low-pressure cleaning with a biocide solution that soaks into the surface and kills mould, algae and lichen at the root.
Because it kills the growth rather than just blasting off the visible layer, it lasts far longer, usually two to four years on render or cladding, and it doesn’t damage the finish the way high pressure can.
Why does the mould keep coming back on the same wall?
Two likely reasons. Either the wall is shaded and stays damp, so growth is always going to return there faster than on sunny walls, or it was cleaned with pressure that left the root alive to repopulate.
Killing the growth at the root with a soft wash is what breaks the cycle, though a permanently shaded wall will still want redoing sooner than the rest.
Is exterior mould dangerous to my health?
Exterior mould is much less of a health concern than mould inside the home, because you’re not living in that air.
It’s mainly a surface and appearance problem, and left long enough it can degrade render and paint.
If mould is also appearing on the inside of the same wall, that’s a different issue worth looking at, and it’s worth a proper investigation by someone from our team.
Will soft washing damage my plants or garden?
Not when it’s done properly.
We wet down the garden beds before and after, keep the solution to the lowest strength that does the job, and rinse the surrounds. The risk of plant damage comes mostly from DIY jobs using the wrong concentration.
How long will it stay clean?
On render and cladding, a proper soft wash generally holds for two to four years.
Shaded, damp or heavily treed walls will be on the shorter end, sunny exposed walls the longer end. We’ll give you a realistic idea for your particular place rather than a one-size number.