Before You Paint It, Try Cleaning It: The Homeowner Mistake That Could Be Costing You!
You’re standing outside, arms folded, looking at your home.
The walls look dull.
Faded.
There are green streaks along the render, and patches of black mould spreading near the base.
Your first thought?
"It’s time for a fresh coat of paint."
But before you reach for the colour chart or call a decorator, ask yourself this:
Are you about to paint over a problem that could be fixed with a proper clean?
Because what many homeowners in Belfast, Antrim, and across Northern Ireland don’t realise is that your home’s exterior might not be old, it might just be dirty.
Looks Can Be Deceiving — Especially in NI
Here in Northern Ireland, our homes take a beating from the weather and I have mentioned this many times in previous blog posts.
We get consistent rainfall, long stretches of damp conditions, and limited sun to dry things out.
Then there are home in shaded areas, covered by overgrown trees, and blocked gutters, and your exterior becomes the perfect habitat for things like:
Algae – creates green vertical streaks
Lichen – white, crusty growths that cling tightly
Black mould – dark patches spreading in damp, shaded zones
Moss – often found near base walls and shaded render
These organisms don’t just sit on the surface.
They feed on dirt and moisture trapped in the render.
They hold water against the wall. And over time, they begin to break it down.
So what looks like fading paint or weathered render might actually be live biological growth, and painting over it doesn’t fix it.
It just hides it… temporarily.
Painting Over Growth: The Expensive Mistake
Let’s say you paint over those green and black patches without cleaning them first. What happens?
The spores trapped underneath survive
Moisture continues to be held against the surface
The paint fails to bond properly
Stains reappear within months
Flaking, peeling, and bubbling follow
You’ve just spent hundreds (maybe thousands) on paint and labour… and you’re back to square one.
And worse?
You now have growth beneath a sealed surface, which is harder to treat and clean later on.
That’s why the right move isn’t painting first.
It’s cleaning.
What Cleaning Actually Reveals
If you go to my website and look at my before and after photos of my previous photos, you’d be shocked at what’s hiding beneath the grime.
It still shocks me everytime I look at them as well, from just a little TLC these homes look brand new.
We’ve cleaned countless homes across Belfast and Antrim where the homeowners were ready to repaint, only to discover that:
The original colour was still vibrant
The render wasn’t stained, just coated in algae
Their house didn’t need paint, it just needed a soft wash
And they saved hundreds of pounds in the process.
Soft washing is the method most often used for render cleaning. It’s gentle, low-pressure, and uses biodegradable cleaning agents to safely remove all organic growth from walls, render, roofs, and patios, without causing damage.
Why Soft Washing Beats Pressure Washing
We need to say this loudly:
Do not pressure wash your render.
While you think you could do this yourself and the idea of saving money is tempting, pressure washing forces water into the surface, strips away protective layers, and often causes cracks or long-term damage.
Soft washing, on the other hand:
Kills algae, moss, mould, and lichen at the root
Doesn’t damage paint or render
Keeps growth from coming back as quickly
Leaves surfaces clean and ready, whether for repainting or just enjoying the view
It’s the method trusted for delicate or older buildings, especially in residential exterior cleaning projects across Northern Ireland.
Why It’s Worse in Northern Ireland
Our weather isn’t just bad for drying clothes.
It's rough on buildings too.
Thanks to our damp climate, exterior walls here tend to stay wet for longer periods than in other parts of Europe.
That means homes in places like Belfast, Antrim, and the surrounding countryside are more prone to moss, mould, and algae-related damage.
And because the damage is slow and subtle, most people don’t notice it until the walls are fully stained, or when internal damp starts creeping in.
Cleaning your home’s exterior regularly prevents all of this, and keeps your home looking fresh and well kept.
Let’s Talk About Your Gutters
Blocked or overflowing gutters are one of the biggest causes of render staining.
When water doesn’t drain properly, it runs down the wall, carrying dirt and debris with it.
Over time, this creates:
Green trails down your render
Water-damaged plaster
Black spots of mould near windows
Deterioration of paint near fascia boards
If you’re thinking of repainting and haven’t had your gutters cleaned in over a year?
Start there.
Because even a perfect paint job can’t survive constant dirty water splashback from above.
Before You Paint, Do This Quick Test
Step outside. Go to your front or side wall.
Place your hand on the render or painted surface.
Does it feel smooth?
Or does it feel chalky?
Slimy?
Damp?
If it’s anything but clean and solid, there’s a problem.
And it’s one that paint alone can’t fix.
This 10-second test can save you hundreds, and prevent you from making a mistake most homeowners only catch too late.
The Cost Comparison: Painting vs Cleaning
Let’s say you’re repainting a semi-detached home in Northern Ireland.
Between materials and labour, you’re looking at:
£1,200 to £2,000, depending on the finish, access, and prep work.
Now compare that to a professional exterior cleaning:
£250 to £500 for a full soft wash of render, walls, and gutters (depending on property size and condition).
And remember, once cleaned, many homeowners decide not to paint at all.
That’s saving around £1,000, just by cleaning first and making an informed choice.
When Should You Clean Your Exterior Walls?
Ideally:
Every 1 to 2 years, depending on weather and exposure
After particularly wet winters
Before selling or photographing your home
Any time you’re considering repainting
When you notice streaks, dark patches, or rough textures forming
By working cleaning into your seasonal home maintenance routine, you protect your home’s value, save money, and extend the life of your render and paintwork.
Preventive Homeowners Are Already Doing This
Across Belfast and Antrim, we’re seeing more and more homeowners think about the exterior of your home and they’re:
Refreshing their homes for summer
Cleaning stained render before deciding on repainting
Booking driveway cleaning ahead of family events
Removing roof moss to prevent long-term tile damage
Getting gutter cleaning done twice a year to avoid splashback and blockages
It’s not about perfection, it’s about protecting what you own.
Paint if You Want But Clean First
To be clear, repainting isn’t a bad decision.
But it’s not the first decision you should make.
Cleaning your home first gives you:
A fresh canvas
A true view of the wall’s condition
A surface that holds paint better
A longer-lasting finish
And often, a reason to skip painting altogether
If you still want to go ahead with new paint, you’ll know it’s needed, and it’ll perform much better over a clean, dry, growth-free surface.
Final Word: Don’t Cover It… Cure It
Most people wouldn’t wax a dirty car.
So why would you paint a dirty wall?
Cleaning before painting isn’t just smart, it’s essential.
Your home is constantly protecting you from the weather.
All it takes to protect it in return is some well-timed care.
So before you buy rollers, tins, or book a painter…
Check your walls
Look at your render
Book a soft wash
Clear those gutters
Then decide what really needs to be done.
You might just find your home’s real colour, hiding under years of dirt.
