Dealing with organic growth on home exteriors
What is organic growth?
Organic growth on the roof, exterior walls or the driveway of your property surfaces is more often than not those green or black blotches you can see. Usually they are tiny organisms, think, algae, lichen or moss and they occur naturally over time, especially on the shady side of a home. As a homeowner and especially from a distance they can tend to look alike. But they do have some significant differences. If you look closely you can usually tell the difference.
Let’s start with the plants! Moss is classified as a plant, so they photosynthesise (use sunlight and water to create food). Moss has a “structure”, so if you touch it you can feel it. Moss will usually wipe off easily because it doesn’t have a root structure and is typically green. Moss thrives with indirect sunlight and water.
Algae used to be considered a plant, but now it’s classified as an aquatic organism that photosynthesises. If there’s not a texture, it could be algae. Algae can be green or red or black. All algae can grow in shady areas with enough moisture and it’s possible for black algae to grow in areas with direct sunlight.
Lichen are a combination organism that have algae or bacteria living within a fungal structure, where the fungus depends on the algae or bacteria to photosynthesise. Like moss, lichen has a structure so you can feel it. Lichen is not so easily removed, because they are a tangle of scaly growth. When wet they will be green, but when they dry they can be virtually any colour.
Why does my home have it?
Organic growth thrives in situations where there’s limited sunlight. So the shady side of your house - here in Texas, think the North side - is prone to moss, lichen and algae growth.
All organic growth is more likely to become established in damp areas, because they all need moisture to thrive, and if it has been an especially rainy year it could explain why this is the first time you’ve seen it! Organic growth thrives on porous substances so your bricks or paint layers might also be contributing.
Can it damage my property?
Yes absolutely! Organic growth will damage the exterior of your home if you don’t act to remove it. It is likely to spread and stain plus it can cause pitting or permanent etching on the surfaces of some types of siding.
Who wants that?!?
How do I get rid of it?
The only way to get rid of organic growth is to clean it! And of course there’s a few options for that.
Whatever the type of organic growth - you will probably be able to scrub it away. If you want to tackle it yourself, start in the gentlest way possible with mild soapy water and a soft bristled brush. If that’s not working use a siding clear labelled as effective for the organic growth that you have, it’s worth knowing that a algicide wont work against mildew and likewise a mildewcide wont work against algae. And if your growth is lichen, you’ll definitely want to be using a cleaner. Make sure you have a ladder up to the task, and time.
A second choice is power washing, with either just water or with some cleaner into the tank. Professional power cleaners will make sure the pressure isn’t too high to damage your property and will know how to choose just the right cleaner for your organic growth problem
How can I keep it away for longer?
When you commit to removing the organic growth through washing it, you’ll never be able to keep it away forever. But using a cleaner (and when you repaint a paint) fortified against organic growth will keep it free from growths for longer.
To be honest, cleaning the exterior of your house once a year with pressure washing will make sure you stay on top of this. It’s best to pressure wash the whole exterior surface not just the organic growth affected areas so your whole home has a clean and even appearance.
If the exterior of you home looks visibly clean and doesn’t have any organic growth, grime or debris buildup then you can pressure wash it once every two years.
