Facade Cleaning Do’s and Don’ts: How to Clean Your Building Exterior Without Causing Damage

A clean building exterior does more than improve curb appeal. Dirt, pollution, biological growth, and staining can all contribute to long-term deterioration if left untreated. But when it comes to facade cleaning, the wrong methods can sometimes cause more damage than the dirt itself.

For facility managers and building owners, understanding the right way to clean exterior surfaces is critical. Different materials require different approaches, and using overly aggressive cleaning methods can permanently damage masonry, stone, EIFS, sealants, or architectural finishes.

At Mid-Continental Restoration, we often see buildings where improper cleaning methods accelerated deterioration rather than preventing it. Here’s what you should know before starting your next exterior cleaning project.

Why Facade Cleaning Matters

Building exteriors are constantly exposed to weather, airborne pollutants, moisture, and biological contaminants like algae or mold. Over time, these elements can discolor surfaces, trap moisture, and contribute to premature aging.

Routine cleaning helps:

  • Preserve the appearance of the building
  • Remove contaminants that contribute to deterioration
  • Extend the life of exterior materials
  • Improve tenant and visitor perception
  • Reveal hidden maintenance issues before they worsen

But the goal should never be simply to make the building look cleaner. The goal is to clean it safely while protecting the integrity of the materials.

Facade Cleaning Do’s

DO Use Low-Pressure Washing for Most Masonry

For brick and many masonry surfaces, low-pressure washing combined with the proper detergent is often the safest and most effective approach. High pressure can force water into wall systems or damage mortar joints, while low-pressure systems gently remove dirt and buildup without harming the surface.

Using the right cleaning solution matters just as much as water pressure. Different stains require different products, and detergents should always be compatible with the building material.

DO Test Cleaning Methods First

Before cleaning an entire elevation, always test the method in a small, inconspicuous area. Materials react differently depending on age, exposure, and prior repairs.

Testing helps verify:

  • The cleaner won’t discolor the surface
  • The method effectively removes staining
  • The pressure level is safe for the material
  • No damage occurs to surrounding sealants or coatings

This step is especially important for historic buildings or mixed-material facades.

DO Use Gentler Methods for Historic Stone and Sensitive Surfaces

Historic masonry and natural stone require extra care. In many cases, steam cleaning or specialized chemical cleaners are preferred because they clean effectively without aggressively eroding the surface.

Historic materials often have softer outer layers that can be permanently damaged by improper cleaning. Once those protective surfaces are removed, deterioration can accelerate significantly.

DO Consider Poultices for Deep Staining

Some stains, such as rust, oil, or biological staining, require more than surface cleaning. Poultices are specialized paste-like materials designed to draw stains out of porous masonry and stone.

While slower than pressure washing, poultices can be extremely effective for targeted stain removal without widespread surface impact.

DO Use Specialized Cleaning for Glass and Curtain Walls

Glass curtain wall systems require their own cleaning approach. Improper chemicals or abrasive tools can scratch coatings, damage sealants, or leave permanent residue.

Professional cleaning teams often use purified water systems, non-abrasive tools, and manufacturer-approved cleaners specifically designed for architectural glass.

Facade Cleaning Don’ts

DON’T Sandblast Historic Brick or Stone

One of the most damaging mistakes in facade cleaning is abrasive blasting on historic masonry. Sandblasting removes not only dirt but also the protective outer surface of brick and stone.

Once that outer layer is destroyed, the masonry becomes more porous and vulnerable to moisture intrusion and freeze-thaw damage. The building may initially look cleaner, but deterioration often accelerates dramatically afterward.

DON’T Use Excessive Water Pressure

More pressure does not equal better cleaning.

High-pressure washing can:

  • Damage mortar joints
  • Crack or erode masonry surfaces
  • Drive water into wall systems
  • Damage sealants and flashing
  • Loosen architectural materials

Many facade issues that appear years later actually begin with improper pressure washing.

DON’T Use Harsh Acids Without Proper Testing

Acid-based cleaners can be effective in some situations, but using the wrong chemical (or using it improperly) can permanently discolor or damage building materials.

Acids should always be tested first and applied according to manufacturer guidelines. Some masonry types and historic materials are especially vulnerable to acid damage.

DON’T Pressure Wash EIFS

EIFS (Exterior Insulation and Finish Systems) requires a much gentler cleaning approach than traditional masonry.

Aggressive pressure washing can force water behind the EIFS system, potentially leading to trapped moisture, mold, or substrate damage. Soft washing methods are generally safer and more effective for these systems.

DON’T Ignore the Underlying Cause of Staining

Cleaning alone doesn’t solve every problem.

If staining keeps returning, there may be an underlying issue such as:

  • Water infiltration
  • Failing flashing
  • Rusting steel components
  • Poor drainage
  • Biological growth caused by trapped moisture

Treating the symptom without addressing the cause often results in recurring problems.

The Importance of a Strategic Cleaning Plan

Facade cleaning should be part of a broader exterior maintenance strategy—not just a cosmetic exercise.

A professional assessment can help determine:

  • The safest cleaning method for each material
  • Whether staining indicates deeper issues
  • Which areas need repairs before cleaning begins
  • How often should cleaning occur based on building exposure and environment

For many buildings, routine cleaning also provides an opportunity to inspect the facade for cracks, sealant failure, or developing maintenance issues.

Protect Your Building While Preserving Its Appearance

A properly cleaned facade enhances appearance, protects materials, and extends the life of the building. But the wrong cleaning method can create costly damage that far outweighs any short-term improvement.

At Mid-Continental Restoration, we help building owners and facility managers evaluate facade conditions, identify appropriate cleaning methods, and ensure exterior systems are protected throughout the process.

Before your next cleaning project, make sure your building is getting the right treatment, not just the fastest one.