When restoring foundations that are a century old or more, stabilization methods must balance modern engineering with historic preservation standards. The most effective methods include:

• Helical Pier Stabilization: This is often the preferred method for historic structures. It uses screw-like steel piers advanced into the ground to reach load-bearing soil. It is highly valued for its low-vibration installation, which protects fragile historic masonry, and its ability to be installed in restricted spaces with minimal excavation.
• Structural Underpinning: This process involves extending the foundation to a deeper, more stable soil stratum. While traditional concrete underpinning is an option, it requires more extensive excavation and curing time compared to steel systems.
• Mortar Repointing: For foundations made of stone, brick, or rubble, repairing deteriorated mortar is essential. It is critical to use lime-based mortars rather than modern high-strength products, as modern cement can trap moisture and cause historic stones to spall or fail.
• Drainage and Moisture Control: Since water is a primary cause of foundation distress, implementing proper site drainage is a fundamental stabilization step to prevent soil heaving and mortar erosion.

Before selecting a method, it is vital to have a structural engineer foundation inspection to perform a forensic evaluation of crack patterns and soil conditions.

• Historic Foundation Restoration: Colorado Homeowner’s Guide