To handle mortar deterioration in stone foundations, we follow a specialized process known as repointing, which is a critical component of historic foundation restoration. Because old stone foundations must be allowed to “breathe,” the repair method and materials used are vital to the long-term health of the structure.

Our approach includes the following steps:

• Hand Tool Removal: We start by carefully removing the deteriorated mortar using hand tools. This protects the original stone from the damage often caused by power tools.
• Material Selection: We use a lime-based mortar that is specifically mixed to be softer than the surrounding stone. Following National Park Service standards, the mortar must be “sacrificial,” meaning it is designed to erode before the stone does. We avoid high-Portland cement mixes, as they can trap moisture and cause the historic stone to crack or spall.
• Application: After dampening the joints, we pack the new mortar in thin lifts. The joints are tooled once the mortar is “thumbprint-hard” to match the historical texture and color.

For more serious issues, such as stair-step cracks wider than 1/4 inch or significant settlement, we may recommend structural underpinning or helical pier stabilization to address the root cause of the movement.

Please note: Estimates are preliminary and subject to change after site inspection and a full scope review. Project outcomes and timelines may vary based on site conditions, permitting, and material availability. Please consult a licensed contractor for definitive advice; verify licensure with the Colorado Department of Regulatory Agencies (DORA).

• Historic Foundation Restoration: Essential Guide to Underpinning