How a Public Health Crisis in 1863 Invented the Brick Curtain Wall

Dec 10

In the 1860s, London faced three major cholera outbreaks that pushed the city to rethink the materials used in its buildings. One rule in particular, passed in 1863, changed architecture more than anyone expected. The government banned absorbent clay tiles in exterior walls because they held moisture and contributed to unsanitary living conditions. The ban forced builders to experiment, and their solution ended up shaping the future of façade design.

The Birth of the First Brick Curtain Wall

With clay tiles off the table, builders needed a new way to enclose buildings without trapping moisture. Their answer was a thin, four-inch brick veneer hung on iron hooks. This was not a load-bearing wall. It was an independent layer that sat in front of the structure with a small air space behind it, allowing moisture to escape. In other words, it was the first rain screen wall.

This early system worked better than anyone realized at the time. By separating the brick from the main structure and allowing airflow behind it, builders unintentionally created a façade that managed water far more effectively than solid masonry.

What Thermal Imaging Shows Today

Modern thermal imaging has confirmed the value of this approach. When exposed to rain, these 160 year old brick veneer walls dry in under two hours. A traditional solid masonry wall, by comparison, can take more than eighteen hours to release trapped moisture. The difference has real consequences for durability, mold resistance, and long term maintenance. The lesson is simple. An air gap matters. It allows water to escape rather than migrate into the structure, and it dramatically improves the lifecycle performance of the wall.

Why New York Should Pay Attention

New York is filled with older masonry buildings that struggle with moisture retention. Many have undergone decades of patching, repointing, and resurfacing, yet moisture problems persist because the wall assemblies were never designed to breathe. In a humid, coastal environment, this becomes an ongoing maintenance burden for owners and a long-term risk for building health. Revisiting the principles of London’s 1863 façade system offers a path forward. Instead of sealing masonry tighter, we should be introducing controlled gaps that allow walls to dry as intended.

The Modern Equivalent: Aluminum Retrofit Brackets

Today, designers can replicate London’s historic performance with simple aluminum bracket systems. These brackets create a consistent air cavity behind thin brick veneers, terra cotta, cement panels, or other cladding. They do not rely on iron hooks or improvised solutions. They offer a predictable, code-compliant way to introduce ventilation and drainage into existing facades.

Most retrofit bracket systems cost around six dollars per square foot. For a typical brownstone or mid-sized multifamily building, the cost is modest compared to the long-term benefits. The system creates an air gap, improves drying time, reduces freeze-thaw damage, and helps prevent façade spalling. It also makes future maintenance easier because the cladding layer becomes removable rather than permanently bonded to the wall.

Building Resilience by Looking Back

The story of London’s clay ban is a reminder that innovation sometimes comes from regulation, necessity, or even panic. By forcing builders to abandon a familiar material, the city accidentally started a design shift that we now recognize as best practice. New York faces a different set of pressures today, from climate challenges to aging buildings. The lesson still applies. Sometimes the smartest move is to let buildings breathe.

A small air gap solved a public health issue in 1863, and it can help solve moisture issues in our city today. If we embrace this simple idea, we can improve building longevity, reduce maintenance costs, and create healthier envelopes without reinventing the entire façade.

Irving Yee