Chicago is home to some of the most distinctive architectural styles in the country, and among the most iconic of these are buildings made of greystones. Built during the late 19th and early 20th centuries, greystones are primarily found in neighborhoods across the city’s North and West Sides. These structures, constructed from Indiana limestone, have become synonymous with Chicago’s architectural identity. However, like any historical building, greystones require care and attention to preserve their beauty and structural integrity. Whether you are a proud owner of one or simply an enthusiast looking to understand their maintenance, here’s a detailed guide on how to maintain a building made of Chicago greystones.
Understand the Unique Properties of Greystone
Greystone buildings are made from a type of limestone, specifically quarried from Indiana. The stone is dense and durable, which is why it has withstood Chicago’s harsh weather conditions for over a century. However, being a natural material, it is prone to weathering and decay over time. Proper maintenance of a greystone begins with understanding the characteristics of the stone itself. Greystones are porous, meaning they can absorb moisture, which can lead to deterioration if not properly cared for.
Regular Inspection is Key
Just like any building, routine inspections are critical for early detection of potential problems. A good rule of thumb is to inspect your greystone building at least once a year, paying special attention to areas exposed to the elements, such as facades, lintels, and ledges. Look for cracks, chips, or signs of water damage. Catching issues early can save time and money down the road.
Common Inspection Areas:
Exterior Walls: Look for cracks or crumbling, as these can indicate larger structural problems.
Mortar Joints: Inspect the mortar between the stones. Over time, the mortar can degrade, causing gaps that allow moisture to seep in.
Window Lintels and Sills: These areas are prone to water damage due to rain runoff and snow buildup.
Roof Flashing: Check for any damage or gaps in the flashing that can lead to water infiltration, which will damage the stone over time.
Tuckpointing
One of the most common maintenance tasks for greystone buildings is tuckpointing. This process involves removing deteriorating mortar from the joints between the stones and replacing it with fresh mortar. Tuckpointing not only helps maintain the structural integrity of the building but also protects it from water infiltration.
When tuckpointing a greystone building, it’s crucial to use the right type of mortar. Modern mortars are often too hard for historic stone buildings and can cause more harm than good. Make sure to use a lime-based mortar, which is softer and more flexible, allowing the building to “breathe” while providing a strong bond between the stones.
Cleaning the Stone
Cleaning a greystone building can enhance its appearance and help maintain the stone’s longevity. However, it’s important to avoid abrasive or high-pressure cleaning methods that can damage the surface. Instead, opt for gentle cleaning solutions and methods.
Recommended Cleaning Methods:
Low-Pressure Water Wash: Use a low-pressure water spray to remove dirt and grime. Avoid using high-pressure washers, which can erode the stone’s surface.
Non-Acidic Cleaners: Many household cleaners are too acidic for limestone and can cause discoloration or damage. Use pH-neutral or specially formulated stone cleaners.
Soft Bristle Brushes: If scrubbing is needed, use a soft-bristle brush to avoid scratching the stone’s surface.
Waterproofing and Sealing
Although greystone is a durable material, its porous nature makes it susceptible to water absorption. Over time, this can lead to erosion, spalling (flaking or chipping), and freeze-thaw damage during Chicago’s cold winters. Applying a breathable stone sealant can help protect your building from moisture damage.
However, it’s important to choose the right type of sealant. Avoid non-breathable sealants that trap moisture inside the stone, which can cause further damage. A breathable, water-repellent sealant allows moisture to escape while preventing water from entering the stone.
Addressing Structural Issues
If your inspection reveals significant structural problems, such as large cracks or shifting stones, it’s crucial to address these issues promptly with the help of a professional. Structural repairs may involve resetting stones, reinforcing the foundation, or other more complex interventions. Don’t attempt major repairs on your own—working with a contractor experienced in historic stone buildings will ensure the longevity and safety of your greystone.
Preserving Historical Character
While maintenance is crucial for preserving the structural integrity of a greystone building, it’s equally important to preserve its historical character. Avoid modern materials or techniques that can detract from the building’s authentic appearance. Whenever possible, use historically appropriate materials, such as original stone replacements or lime-based mortars, to maintain the integrity of the original design.
Winter Care
Chicago’s winter can be especially harsh on greystone buildings. Snow and ice buildup can cause significant damage if not properly managed. Regularly remove snow from areas around your building, particularly on steps, lintels, and sills, to prevent water from seeping into the stone. Salt and de-icing chemicals can also damage the stone, so use them sparingly and consider using less corrosive alternatives.
