Repairing an Old Home's Cracking Brick Foundation: The Comprehensive Guide

When dealing with an old home with a crumbling brick foundation, it's crucial to understand the underlying causes and take appropriate corrective measures. This guide breaks down the steps to properly address these issues, ensuring long-term stability and longevity of your property.

Identifying the Cause of Foundation Cracks

Before embarking on any structural repairs, it's essential to diagnose why the cracks have appeared in the first place. Foundation cracks are often indicative of a larger problem, commonly attributed to either subsidence or heaving. Here’s how to determine the cause:

Subsidence

Subsidence occurs when the ground beneath the foundation settles, leading to cracks in the brickwork. Possible causes include:

Lowering of water tables, such as during periods of drought Presence of hidden subsurface voids Deterioration of support structures under the foundation

To diagnose subsidence, place a telltale across the cracked area and observe if it widens over time. If the crack grows larger, it’s likely due to active subsidence. Stabilizing these cracks often involves jacking and installing auger-style supports to hold the foundation in place while high-pressure grout is injected into the void below. Finally, the cracks can be repaired using epoxy grouting.

Heaving

Heaving is characterized by upward displacement of the foundation. This can be attributed to:

Expansive soil under the foundation absorbing water Nearby trees extracting water from the soil Inadequate drainage practices, such as poor guttering or hose bib water runoff

A quick test to determine if you have expansive soil is to hydrate a soil sample and form a ball in your hand. If the ball holds together, it's likely expansive. Addressing heaving cracks often involves identifying and resolving the source of water infiltration. Ensuring minimal soil moisture near the foundation, redirecting water away from the building, and possibly regrading the area to deter water from flowing towards the structure are effective strategies.

Preparation and Monitoring

Before making any repairs, it's vital to wait and monitor the situation. If the crack remains static or stops getting larger after a month, it may indicate that the underlying issue has been resolved. However, if the crack continues to grow, foundation repair is necessary.

Checking for Active Subsidence

For cracks caused by subsidence, active subsidence must be confirmed and addressed. This might involve:

Repairing leaking drainage systems Removing problematic trees Installing underpinning to support the foundation

Active subsidence cracks are typically stabilized using jacking and installing auger-style supports to hold the foundation in place while grout is injected into the void below. Once stabilized, the cracks can be epoxy grouted to ensure the foundation is structurally sound.

Long-Term Monitoring and Maintenance

Regular monitoring is essential to ensure the stability of your foundation. To help monitor the situation, place a piece of string or fishing line across the widest part of the crack and check it periodically for any changes. If the crack continues to move, further investigation and possibly additional stabilization measures are required.

Additional Measures

In some cases, regrading the area around the building to move water away from the structure or constructing a 'dam' using compacted expansive soil can help mitigate heaving. Ensure to remove any granular soils first to prevent water migration. Following these steps can lead to long-term foundation stability and a reinforced home structure.