Understanding the Vital Role of Building Foundations and Its Impact on Structural Safety

Many aspects of a building structure garner attention, yet the foundation often goes unnoticed. It's easy to fall into the misconception that once a building is grounded, it remains stable. However, the earth beneath a structure can be the most unpredictable environmental factor affecting it. Significant earth movements can lead to severe damage to the structural framework. One of the top contributors to hazardous conditions in buildings is the foundation movement. Below, we delve into instances where neglecting or underestimating the critical role of the foundation system can result in inferior foundation crack repairs, leading to further damage or safety issues.

1. Balancing the Act of Underpinning Repairs and Avoiding Undermining

Various foundation repair companies offer solutions to manage cracks in foundation walls, such as underpinning, involving methods like simple concrete footings, piles, or helical piers. An example is shown below with a helical pier attached to the foundation.

The purpose of underpinning is to tackle issues arising from inadequate soils beneath the existing building foundations, which fail to support the building loads. The process of underpinning transfers these loads to the deeper, more robust soil strata. The challenge of underpinning, as hinted in the name itself, lies in the "under" part. To transfer the load, a portion of the foundation bottom needs exposure. Undertaking underpinning with careful sequencing helps prevent additional movement. However, if the sequence isn't correctly executed, it can lead to disastrous results, as demonstrated by the chimney collapse below.

Underpinning is achievable even in extreme situations:

2. The Consequences of Adding Supports Without a Proper Foundation

In many instances, one may find additional supports in basements and crawlspaces that were incorporated post the original construction. These could be due to undersized or rotted framing or changes in building loads. When adding these supports, the foundation must not be neglected. The foundation must be durable (preferably concrete), adequately sized for expected loads, and installed at a depth similar to the adjacent foundations to prevent uneven settlement.

The image below shows a case where additional support with its foundation is laid directly on the crawlspace soil. When a pipe leak occurred, the shallow foundations of these supports settled more than the original ones, causing drywall cracks.

3. Missteps in Pressure Grouting

Pressure grouting is another foundation repair method. It involves using a rig to drill and install pipe casing for grout injection into the soil, aiming to fill voids and compact the surrounding soil to restore adequate foundation support.

Though highly effective for repairing voided soils and foundation movement, pressure grouting can exert significant force on foundations and foundation walls. To avoid damaging nearby structures, it's essential to monitor ground heave, grout pressures and grout take amounts diligently. Failure to implement these controls can lead to foundation damage, as seen in the following image of a collapsed foundation wall.

Getting Your Foundation Assessment Right

If you're left wondering about the origin of cracks in your foundation walls, why a wall is bulging, or what caused a foundation collapse, don't hesitate to reach out to the experts at General Forensic Engineers, LLC. Our team of foundation crack experts in your local area is on standby to help you navigate these complex assessments.