Soil Layers: What Are They?

What Are Soil Layers? 

Soil layers are deposits that form over a long period of time, consisting of various materials such as rocks, clay, and sand. Several factors affect soil layers and their physical properties, including wind, water, glaciers, and human activities such as construction.

These layers gain strength and capacity to bear weight over time. Beneath these layers are inert types of soil, known as bedrock, consisting of hard rocks that don’t compress or shift.

Types of Soil Layers 

Man-Moved Soil

Man-moved soil refers to soil that builders dig up and move to another location for construction purposes. Due to the lack of quality soil in urban areas, the need for man-moved soil has risen in recent decades. This type of soil can be categorized into three types:

• Engineered Fill Soil: Consisting of granular materials or select subgrade soils, it compacts in thin lifts and can provide support for a foundation to some capacity.
• Dumped Fills: These fills have less gravel and stones, providing cover for landfills, but may need re-engineering for foundation support.
• Hydraulic Fills: Including select particles of heterogeneous soil, they are moved using water streams and can be treated as native soil if they have reasonable compressible characteristics.

Backfill Soil

• Coarse-Grained Soil: A mixture of gravel, sand soil, and a negligible amount of fine materials, providing fine support for the foundation.
• Limestone Screenings: Easy to compact and great for sewer and pipe backfills.
• CA7 Bedding Stone: Self-compacting, used for bedding pipes and improving soil drainage.
• Commercial By-Products: Used when previously dug-up soil is not suitable.

Clay Soil

Clay soil, also known as expansive soil, contains tiny particles that pack tightly, leaving little room for air. It absorbs a lot of water, causing it to expand, and shrinks when dry. This constant cycle of expanding and contracting can put a lot of stress on a home’s foundation. Characteristics of clay soil include:

• High Water Absorption: Swells up like a sponge when wet.
• Sticky Texture: Difficult to work with when wet.
• Hard and Cracked: Becomes hard and cracks easily when dry.

Bedrock

Bedrock, or load-bearing strata, is the hard rock beneath a structure. It doesn’t shift or compress, making it ideal for carrying heavy loads. Experts call it “non-active soil”, which means that bedrock is inert.

Unlike silty sand or clay soil, bedrock doesn’t expand or contract. Expansive soil usually contains limestone, sandstone, or another type of rock. Bedrock is stable no matter what kind of weather affects it. 

Glacial Deposits 

How Soil Layers Affect Your Foundation

Soil layers are very important for your foundation. Different types of soil can either support or weaken your foundation.

For example, clay soil can expand and contract with moisture changes, causing your foundation to settle and its walls to crack. Soft or unstable soil like fill soil can lead to sinking if not properly compacted.

Knowing the soil conditions at your building site helps ensure your foundation is strong and stable. We can’t necessarily control soil, but we can control how we respond to it.

Soil Layers and Foundation Repair

If you’re having problems with your foundation due to the soil underneath, it’s essential to contact professionals immediately. Our crew at AFS will provide you with a free inspection and repair quote, offering solutions such as:

• Foundation Push Piers: Galvanized steel piers provide support and lift the home back to its original position.
• Foundation Helical Piers: Screwed into the ground to transfer the house’s weight to stable soil.
• Steel I-Beams: Reinforcing and stabilizing basement walls pushed inward by expanding clay soil.
• Wall Anchors: Stabilizing and strengthening bowed walls due to soil pressure.
• Crawl Space Support Jacks: Stabilizing and lifting sagging floors in crawl spaces.
• Slab Piers: Installed below concrete slabs to address settlement issues.

Addressing foundation issues quickly is crucial for your home’s stability and safety. Different soil types can impact your foundation, so it’s important to prevent further damage with the right repair option.

Protect Against Soil Issues With AFS

Related Resources

Homeowner’s Guide to Clay Soil & Foundation Damage

Clay soil can cause foundation problems. Learn why here!

A Guide to Foundation Repair for Different Foundation Types

When foundation damage occurs, it puts your entire home at risk. In this guide, we'll outline the various ways to repair a foundation and why doing so is a valuable investment in the long-term.

Are Foundation Cracks Normal?: When to Worry & How to Repair

One of the questions we see homeowners as all the time is "are foundation cracks normal?". The short answer is sometimes, but that doesn't mean they're "safe".

Ted Dryce

Content Writer

Ted is an SEO Content Writer who has been with Groundworks since 2021. He’s covered home repair topics ranging from crawl space encapsulation to regional soil conditions. When he’s not working, Ted is performing improv comedy and working on his own creative projects.