Brick is built to last, but Central Pennsylvania weather can make it look worn long before it is. Winter salt, spring pollen, humid summers, algae, and runoff leave exterior brick dull, streaked, or stained. Knowing how to clean exterior brick safely matters because the wrong pressure, cleaner, or technique can damage mortar joints and force water where it does not belong.
A careful cleaning can bring back the natural color of a brick home, chimney, retaining wall, storefront, or entryway. The goal is not to blast the surface until it looks new. It is to remove the buildup while protecting the brick and mortar that hold the wall together.
Start by Identifying What Is on the Brick
Not every dark spot needs the same treatment. Dirt and pollen often rinse away with water and a mild detergent. Green, black, or patchy growth is commonly algae, mildew, or mold caused by shade and moisture. White, chalky residue is usually efflorescence, which occurs when moisture carries salts to the brick surface. Rust, oil, paint, and hard-water stains require more specialized products and more caution.
Take a close look before choosing a cleaner. If the brick feels soft, flakes when touched, has crumbling mortar, or shows cracks, do not pressure wash it. Cleaning will not solve a masonry repair issue, and high pressure can make an existing problem worse.
Older brick deserves extra care. Historic homes and structures with softer, handmade brick may not tolerate the same cleaning method as newer, harder-fired brick. In those cases, gentle hand cleaning or a professional assessment is usually the better call.
How to Clean Exterior Brick Safely
Begin on a dry, mild day when temperatures are above freezing. Avoid cleaning in direct, intense sun if possible, since cleaners can dry too quickly and leave uneven results. Move patio furniture, cover nearby plants, and wet landscaping before applying any cleaning solution. Keep windows and doors closed, and protect electrical fixtures or outlets near the work area.
Start with the gentlest method first. Rinse the brick with a garden hose to remove loose dirt, cobwebs, and pollen. Do not use a high-pressure nozzle close to the wall. A steady, broad spray is enough for the initial rinse.
For general grime, mix a small amount of mild dish soap with water in a bucket. Apply the solution with a soft-bristle brush, working from the bottom upward to reduce streaking. Let it sit briefly, then scrub lightly in small sections. Rinse each section thoroughly from the top down before the soap dries.
This approach takes more time than blasting the wall with a pressure washer, but it is the right place to start for most brick surfaces. Many walls look significantly better after a basic wash and rinse.
Treat Algae and Mildew Carefully
Dark biological growth needs more than soap alone. Use a masonry-safe cleaner designed for algae, mildew, or mold, following the product instructions exactly. Apply it evenly, allow the proper dwell time, and rinse completely.
Do not assume stronger is better. Bleach-heavy mixes can discolor some materials, harm landscaping, and create runoff concerns if used carelessly. They can also leave visible color variation if they dry on the brick. A professional cleaning crew uses the right dilution, application method, and rinse process for the surface and surrounding property.
If growth returns quickly, look for the cause. Overhanging branches, poor drainage, leaking gutters, and constantly shaded areas keep brick damp. Cleaning removes the visible problem, but correcting the moisture source helps the result last longer.
Remove White Salt Residue Without Overreacting
Efflorescence is common on brick, especially after wet seasons and freeze-thaw cycles. It may look like a white powder or crust. In mild cases, allow the wall to dry completely and brush the residue away with a dry, stiff nylon brush. Then rinse lightly with clean water.
Avoid using metal brushes, as they can scar the brick or leave particles that later rust. Avoid sealing over active efflorescence, too. The moisture causing the salts to migrate needs to be addressed first, whether it is from a drainage issue, a leaking downspout, or water getting behind the wall.
Persistent efflorescence may need a masonry-specific cleaner. Acidic products can be effective, but they are not a good first choice for a homeowner. Used incorrectly, acid can etch brick, weaken mortar, damage adjacent surfaces, and create safety hazards.
Can You Pressure Wash Brick?
You can pressure wash some exterior brick, but that does not mean every brick wall should be pressure washed. The condition of the masonry, age of the home, type of stain, and strength of the mortar all matter.
High pressure aimed directly at brick joints can remove mortar, drive water behind the wall, and loosen deteriorated material. A surface may look clean right away but develop costly issues later. The risk is higher with old mortar, loose or spalling brick, cracked joints, and walls that have already absorbed a lot of moisture.
When pressure washing is appropriate, it should be controlled. Use low pressure, a wide fan tip, and a safe working distance. Keep the spray moving and avoid concentrating water on one spot. Never spray upward beneath siding, into weep holes, around windows, or directly into mortar joints.
For many brick cleaning jobs, a soft washing approach is safer. Soft washing relies on surface-appropriate cleaning solutions and low-pressure rinsing rather than force. It is especially useful for algae, mildew, organic staining, and general weather buildup. The right method depends on what is on the brick, not just how dirty it looks.
Clean Stains in Small Test Areas First
Before applying any cleaner to a large wall, test it in a small, less visible area. This step helps you check for discoloration, unexpected reactions, or changes in the mortar. It also shows whether the product is strong enough to work without moving to a harsher option.
Rust stains, paint overspray, oil spots, and mineral deposits are not standard cleaning jobs. A cleaner that works on one stain can permanently damage brick when used on another. For example, aggressive paint removal can pull material from the brick face, while the wrong degreaser may leave a dark halo around an oil stain.
If the stain is deep, widespread, or near a highly visible entryway, professional cleaning is often less expensive than repairing a damaged wall after a DIY attempt.
Do Not Ignore Mortar and Brick Damage
Cleaning gives you a good opportunity to inspect the wall. Watch for missing mortar, crumbling joints, loose brick, cracks, spalling, or areas that stay damp. Spalling means the face of the brick is breaking away, often because water has entered the masonry and freeze-thaw cycles have pushed it outward.
These are repair concerns, not cleaning concerns. Stop washing if you notice material coming off the wall. A masonry professional may need to repoint damaged joints or correct the water issue before the wall is cleaned.
Sealers also require careful consideration. A breathable masonry sealer can help in certain situations, but sealing a wall that traps moisture may make deterioration worse. Brick needs to release moisture naturally. The right product and preparation depend on the wall, its exposure, and whether there is an existing moisture problem.
When Professional Brick Cleaning Makes Sense
A professional is the practical choice when you have a large brick exterior, delicate or older masonry, heavy organic growth, stubborn staining, or concerns about water damage. Commercial buildings also benefit from a consistent approach, especially around entrances, walkways, loading areas, and customer-facing walls where appearance matters.
At 717 Power Washing, we adjust the cleaning method to the material and condition of the property. That means looking beyond the stain, using surface-appropriate solutions, and avoiding the kind of excessive pressure that can harm mortar and brick. What we quote is what you pay, and we show up when we say we will.
Clean brick should look cared for, not stripped, blotchy, or damaged. If you are unsure whether your wall needs a gentle wash, stain treatment, or masonry repair first, getting a clear assessment is the safest next step for protecting your property.