Have you ever looked at one side of your house and wondered why it's turning green? You're not alone. Many homeowners notice that one wall looks different from the others. Usually, it's the wall that faces north.
That green stuff? It's algae. And it's doing more than just making your house look dirty.
Let's talk about the secret life of algae and what you can do about it.
What Is Algae, Anyway?
Algae are tiny living things. Think of them like very small plants. They're so small you can't see just one. But when millions of them group together, they make that green or black coating you see on walls, roofs, and sidewalks.
Algae are everywhere. They float in the air. They land on surfaces. And when they find a spot they like, they start to grow.
Your north-facing wall? Algae think it's the perfect home.
Why Does Algae Love North-Facing Walls?
Here's the simple answer: north-facing walls stay wet longer.
The sun travels across the southern part of the sky. That means south-facing walls get lots of direct sunlight. The sun dries them out and heats them up. Algae don't like that.
But north-facing walls? They stay in the shade most of the day. After it rains or when morning dew forms, these walls stay damp for hours. Sometimes all day.
Algae need three things to grow:
- Moisture – Water helps algae survive and spread
- A little bit of light – Just enough for energy, but not too much
- Food – Dust, pollen, and dirt on your siding feed algae
North-facing walls have all three. The shade keeps moisture around. There's just enough indirect light. And over time, dust and pollen stick to the surface.
It's like a buffet for algae.
Other Things That Help Algae Grow
It's not just about which way your wall faces. Other things can make the problem worse:
- Trees and bushes nearby – They block airflow and create more shade
- Poor drainage – Water that pools near your foundation keeps walls wet
- Certain siding types – Wood siding holds moisture more than vinyl or brick
- Humid weather – If you live somewhere muggy, algae grows faster
If your home has any of these, you might see green growth even sooner.
What Is Algae Doing to Your Siding?
Here's where it gets serious. Algae isn't just ugly. It's actually hurting your home.
1. It Traps Moisture Against Your Walls
When algae grows on your siding, it acts like a wet blanket. It holds water against the surface. Over time, this moisture can seep into your siding material.
Wet siding leads to bigger problems like mold and mildew. These can spread to the inside of your walls. That's not good for your home or your health.
2. It Breaks Down Your Siding
Algae don't just sit there. Some types actually eat the materials in your siding. On roofs, a type of algae called Gloeocapsa magma feeds on the limestone in shingles. This makes shingles wear out faster.
On walls, algae growth speeds up decay. Paint can peel. Wood can rot. Even vinyl can become discolored and brittle over time.
3. It Creates Slippery Surfaces
When algae spreads to walkways, decks, or patios, it gets slippery when wet. This is a safety hazard. Someone could slip and fall.
4. It Hurts Your Home's Value
Let's be honest. A house covered in green gunk doesn't look great. If you ever want to sell your home, curb appeal matters. Algae makes your home look old and uncared for.
A clean exterior, on the other hand, makes a great first impression.
Can You Just Ignore It?
Some people think algae will go away on its own. Unfortunately, it doesn't work that way.
Once algae finds a good spot, it keeps growing. It spreads. And the longer you wait, the harder it is to remove. The damage gets worse over time.
Ignoring algae is like ignoring a small leak. It only gets bigger.
How Do You Get Rid of Algae?
Good news: you can remove algae and protect your home. The best way to do it is with professional house washing.
But not all cleaning methods are the same.
Why Soft Washing Works Best for Siding
For siding covered in algae, soft washing is the way to go.
Soft washing uses low water pressure and special cleaning solutions. The cleaners kill algae at the root. They also remove mold, mildew, and dirt without damaging your siding.
High-pressure washing can be too harsh for some siding types. It can force water behind panels or strip paint. Soft washing is gentle but effective.
The cleaning solutions used in soft washing are designed to:
- Kill algae and prevent regrowth
- Remove stains and discoloration
- Protect your siding from future damage
After a soft wash, your walls look brand new. And they stay cleaner longer.
If you want to learn more about how soft washing compares to other methods, check out this helpful guide.
5 Ways to Prevent Algae Growth
After your home is clean, you'll want to keep it that way. Here are five simple tips:
- Trim trees and bushes – Give your walls more sunlight and airflow
- Fix drainage issues – Make sure water flows away from your home
- Clean gutters regularly – Clogged gutters overflow and wet your walls
- Schedule regular house washing – Once a year keeps algae from coming back
- Watch for early signs – Catch green spots early before they spread
Prevention saves you money in the long run. It's easier to stop algae than to fix the damage it causes.
When Should You Call for Help?
If you see green, black, or dark streaks on your siding, it's time to act. Don't wait until the problem gets worse.
A professional house washing service can:
- Assess the damage
- Remove algae safely
- Protect your siding from future growth
At Red Moose Exterior Cleaning, we use soft washing to clean siding the right way. We get rid of algae without harming your home. Our team knows exactly how to treat north-facing walls and other trouble spots.
The Bottom Line
That green stuff on your north-facing wall isn't just a cosmetic issue. Algae traps moisture, damages your siding, and lowers your home's value. The longer it stays, the worse it gets.
But you don't have to live with it.
Professional house washing with soft washing removes algae and protects your home. It's safe, effective, and keeps your exterior looking great.
Ready to say goodbye to algae? Contact Red Moose Exterior Cleaning today and let's get your home looking its best.