Why is my concrete dirty?

Algae Facts Concrete

August 3, 2017

Your sidewalks and driveway are usually the first things people see when they arrive at your home. It can be embarrassing if your concrete is stained with black or green algae, mold and mildew or has slippery patches. If you are trying to sell your home, raise the market value of your property or entertain throughout the summer, it is something you want to resolve as quickly as possible.

Concrete is surprisingly porous and with all its nooks and crannies it is a wonderful environment for mold. Additionally, wet, humid weather and warm temperatures improve growing conditions


Black Algae

Unfortunately, black algae is hardy and can grow just about anywhere there is a little moisture. The dark coloring protects it from the sun’s rays so that even in the area with the most sunlight, it can still survive. It shows up on your driveway and sidewalk a dark charcoal gray color and mimics the look of soot.

Green Algae

Green algae love shade. Areas of your concrete that are shaded by the shadow of your home, trees or deck may be susceptible to growth. It brings a green shade to your otherwise sparkling sideway and can be hazardous because it is extremely slippery. It is not something you want to expose family and friends to as they walk up to your home.


Lichen is a multi-faceted growth that can grow almost anywhere outside, including your driveway, sidewalk, deck and landscaping. It is very hardy and comes in many colors including green yellow and red. It is an unwanted guest that can difficult to remove because it has a root system.


Mold, black algae, green algae, and lichen can grow on your outdoor hard surfaces and make them appear dirty. Not only does it look messy, but it can be slippery and bring harm to your friends and family. Additionally, some strains can cause damage and be difficult to remove.

If you have pressure washed the area, then you know the muddy mess it creates. It can also cause loose concrete pieces to break off. The cycle continues after you have pressure washed with the moist concrete allowing for algae and mold to start growing again after you finish the process.

Soft Wash

Our Soft Wash process removes moss, mildew, and algae from all affected areas on your property. Through a combined process of a gentle spray and environmentally safe cleaning solutions, the unsightly growths are removed and prevented. We do provide pressure washing services when needed on particularly tough stains like grease and oil that has accumulated.

IDW will prepare and clean the area where bacteria has taken root, giving you the peace of mind knowing that your property is in better condition and safer for everyone around it. Contact us today with any questions about the condition of your walkways, decking, fence or driveway. We will be happy to go over the Soft Wash process with your or give you an estimate for your property.