The historic brickwork of Washington D.C. and Old Town Alexandria is more than just an aesthetic—it is a structural legacy. However, if you own a 19th-century rowhouse, you may have noticed your bricks flaking, peeling, or “crumbling” into a fine red powder. This phenomenon is known as spalling, and if left untreated, it can compromise the very integrity of your home’s exterior.
At Miller & Sons, we believe that true preservation starts with understanding how these historic materials were designed to function.
Why Historic Bricks “Breathe” Differently
Unlike modern, hard-fired bricks, historic masonry is relatively porous. It was designed to work as a “breathable” system alongside soft, lime-based mortars. When moisture enters a historic wall, it needs a way to escape. In a healthy system, the mortar acts as a “sacrificial bodyguard”—it is softer and more porous than the brick, allowing moisture to evaporate through the joints rather than the brick face.
The trouble begins when modern “fixes” are applied to these classic structures.
The Main Culprits of Brick Decay
The “Portland Cement” Trap: One of the most common mistakes is repointing historic brick with modern Portland cement. Modern cement is incredibly hard and waterproof. When moisture gets trapped behind it, it cannot escape through the joints. During a typical Mid-Atlantic freeze-thaw cycle, that trapped water expands, exerting massive pressure on the brick. Since the cement won’t budge, the face of the brick literally “pops” off.
Improper Cleaning: High-pressure power washing (anything over 600 PSI) can strip the protective outer “skin” of an old brick, exposing the softer, more absorbent interior to the elements.
Trapped Moisture: Leaky gutters or poor site drainage can cause “sheeting” water, which oversaturates the masonry.
How to Protect Your Masonry Investment
Preserving a historic home requires a “do no harm” approach. To prevent spalling and ensure your home lasts another century, follow these essential maintenance steps:
Use the Right Mortar: When repointing, always use a traditional lime-based mortar that matches the original in color, texture, and—most importantly—compressibility.
Low-Pressure Cleaning Only: Prioritize low-pressure steam or gentle chemical washes that lift grime without etching the delicate brick surface.
Inspect Your “Water Paths”: Ensure that downspouts and gutters are clear and directing water away from the foundation. Even a small “shelf” created by a previous bad mortar job can trap enough water to cause localized spalling.
Expert Care for Your Historic Investment
Your home’s exterior is its first line of defense against the elements. Proper maintenance today prevents a massive structural repair bill tomorrow. If your historic brick home is showing signs of “scaling,” white salt deposits (efflorescence), or mortar loss, don’t wait for the damage to reach the interior of your home.
Is your historic property showing signs of wear? Contact Miller & Sons today for a professional exterior assessment.
