Several factors are at play in Lancaster that leave homes prone to foundation problems. We’ll provide an in-depth analysis and explanation of these issues below and their effect on your structure.
Sandy Soil
Lancaster is situated predominantly on sandy, gravelly soil that was deposited by alluvial fans of rivers that have since dried.
The majority of Lancaster County is underlain by the Pennsylvania state soil, Hazelton. Hazelton and the other soils in Lancaster are characterized not only by their sandy structure but also by the rapidity with which they drain.
Sandy, excessively-drained soils present several problems for concrete foundations.
The first and most severe issue is that sand-rich earth is prone to erosion. Sand particles are significantly larger than clay and silt, the two other typical soil constituents.
When runoff from precipitation drains through the earth, it can easily bring the large sand particles with it.
This process of underground erosion can create instability under and around your home. It generally occurs at varying rates beneath your home’s foundation, causing differential settling of your structure.
Differential settling contributes to severe structural damage and can result in total foundation failure.
Another significant problem presented by sandy soil is water intrusion and hydrostatic pressure on your concrete block walls. The erosive quality of the ground in Lancaster and water’s tendency to collect and drain around the perimeter of your foundation regularly creates underground voids against your concrete.
These voids can fill with water during rainfall and leave your foundation prone to water intrusion through pores in the concrete or foundation cracks.
It also weighs much more than the soil that typically supports your foundation walls, and it can cause inward movement and eventual cracking of the concrete if the hydrostatic pressure becomes too intense.

Above-Average Rainfall
Lancaster experiences approximately 44 inches of rain each year, which is nearly 50% higher than the average precipitation throughout the United States. The above-average amount of rain contributes to the issues with sandy soil.
Heavy precipitation can carry more sand particles with it, making the risk of underground erosion and differential settling higher.
Concentrated rainfall is more likely to create and fill voids against your concrete with water, increasing the chance of liquid water or water vapor entering your home and leaving you with water damage and several other related problems.
Flooding
Lancaster is relatively flat and lies in a valley, meaning that it’s prone to flooding. Heavy rain may have difficulty draining away from the city, and properties bordering or close to the Susquehanna River are especially at risk of river overflow.
Flooding is dangerous because of the inherent risk of water damage, but it also contributes to underground erosion. It also exposes your concrete to moisture for extended periods, increasing the chance of a leaky basement and moisture build-up under your home.
Limestone Bedrock & Sinkholes
Lastly, a large portion of Lancaster is underlain by limestone and dolomite bedrock. These minerals typically provide ample support, but they dissolve slowly in the presence of water.
Runoff and water from Pennsylvania’s aquifer can gradually deteriorate the bedrock in Lancaster, resulting in a phenomenon called karst.
The subterranean caverns and channels that result from heavy bedrock erosion leave the soil above without support. They can collapse and cause instability under and around your home, usually in the form of sinkholes. Sinkholes present a serious issue for Lancaster foundations, as they can contribute to massive differential settling and foundation collapse.