Mold, Mildew & Moss on Brick: Why It Happens, What It Does, and How to Fix It

Brick is one of the most durable and attractive materials used on homes, but it isn't immune to organic growth. Over time, you may notice mold, mildew, algae, or moss developing on your brick walls.

So why does it happen, what problems can it cause, and what can you do about it?

Why Does Mold, Mildew, and Moss Grow on Brick?

The biggest factor is moisture. Brick is porous, meaning it can absorb and retain water. When brick stays damp for extended periods, it creates an environment where organic growth can thrive.

Several conditions can contribute to growth:

• Shade: Areas that receive little sunlight stay damp longer.

• Humidity: High humidity provides moisture that mold, mildew, and algae need to grow.

• Rain and moisture: Frequent rainfall can keep brick surfaces wet.

• Trees and vegetation: Overhanging trees can block sunlight and increase moisture around your home.

• Poor airflow: Limited airflow can prevent brick from drying properly.

• Organic debris: Dirt, leaves, and other debris can provide additional nutrients for organic growth.

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This is why you may see more growth on shaded sides of your home, underneath trees, or in areas that stay damp.

What Negative Effects Can It Have?

It Hurts Your Home's Curb Appeal

One of the first things homeowners notice is the appearance. Green moss, dark stains, mold, and mildew can make an otherwise beautiful brick home look dirty, neglected, and older than it actually is.

It Can Hold Moisture Against the Brick

Moss and other organic growth can retain moisture against the surface. Constant moisture isn't ideal for masonry and can contribute to deterioration over time, particularly when water is able to penetrate cracks or damaged mortar.

It Can Affect Mortar Joints

Brick itself is durable, but the mortar joints between bricks can be more vulnerable. Persistent moisture and biological growth can contribute to deterioration of already weakened or damaged mortar.

It Can Continue to Spread

Once conditions are favorable, organic growth can spread across additional areas of your home's exterior. What starts as a small patch of green or dark discoloration can eventually become a much larger cleaning problem.

It Can Make Your Home Look Unmaintained

Even if the brick itself is structurally sound, heavy organic buildup can give the impression that the home hasn't been properly maintained.

How Do You Remove Mold, Mildew, and Moss From Brick?

The solution starts with proper exterior cleaning.

Professional soft washing uses specialized cleaning solutions and controlled water pressure to treat organic growth without relying solely on high-pressure water.

Rather than aggressively blasting the brick, the cleaning solution helps break down mold, mildew, algae, moss, dirt, and other organic buildup so it can be rinsed away.

Why Not Just Pressure Wash the Brick?

Brick is strong, but using excessive pressure isn't always the best approach. High-pressure cleaning can potentially damage softer brick and deteriorate mortar joints, especially when the wrong pressure or technique is used.

A professional cleaner can determine the appropriate cleaning method and pressure for your specific brick and its condition.

How Can You Help Prevent Organic Growth?

While you can't completely prevent mold, mildew, algae, or moss from returning, you can reduce the conditions that encourage growth.

Keeping gutters functioning properly, trimming vegetation when appropriate, improving airflow, and keeping exterior surfaces clean can all help.

Regular professional exterior cleaning can also prevent organic buildup from becoming excessive.

The Bottom Line

Moisture, shade, humidity, and limited airflow are some of the biggest reasons mold, mildew, algae, and moss grow on brick homes.

If left untreated, organic growth can negatively affect your home's appearance, hold moisture against surfaces, and contribute to deterioration where masonry or mortar is already vulnerable.

The good news is that professional brick soft washing can safely and effectively remove much of this buildup and restore the clean appearance of your home's exterior.