How Does Soil Compaction Affect my Home’s Foundation?

Soil compaction for construction is a relatively newer phenomenon than most people realize. As we’ve come to understand the concepts, practices, and effects, the regulations have changed over time. 

Having soil compacted is important for your home to avoid foundation issues. Even then, it doesn’t guarantee you’ll never have foundation issues. 

Dalinghaus Construction has inspected over 10,000 homes and 2,000 projects in Southern California, Arizona, and Nevada, all having to do with soil impacting a residential home or commercial structure. We understand soil compaction and its importance. We want you to know its significance to any structure, whether it’s residential or commercial.  

What does soil compaction do for your home?

The purpose of soil compaction is so the soil can support a structure. If there’s anything you want, it’s solid ground that can carry the load of a structure.

About Soil Compaction

In the 1960s, there weren’t compaction tests at all. Checking for soil compaction was very minimal. 

There weren’t over-excavation and compaction standards like today, where regulations are far more prominent. 

Now, they test the compaction of the soil, grade, add another layer of soil, grade, and repeat over again until reaching the top layer.

Checking soil compaction is to understand how dense the soil is to hold the load of a structure. 

The soil compaction rate now is at 95%.

These rates change over time as more is understood about soil compaction. 

What if the soil isn’t properly compacted?

Moisture is the key when it comes to compromised soil. You’ll have water intrusion, which will soften up the soil and make it likely the heavy structure will start to compress the soil. 

So you can deal with either foundation settlement or foundation heaving. Both phenomena can result in damage to your home. 

Foundation settlement

This happens when the soil beneath your home shifts, causing affected areas of your home to sink.

Foundation settlement is a common occurrence compared to heaving, especially in Southern California, Arizona, and Nevada.

For a more in-depth look, check out What is Foundation Settlement? (Soil, Water, and Time).

Foundation heaving

When expansive soils take in moisture, it causes them to… well, expand. The expansion results in affected areas of your home being pushed upward. 

While less common, it is still a common enough occurrence. 

What if the soil is graded to mitigate water?

You can still see issues occur. It lessens the chance significantly, but the chance is there, nonetheless. 

You’re in a much better situation if moisture is being directed away from your home. 

Learn about water mitigation through our article How Does my Foundation Handle Flooding/Moisture?

What’s used to compact soil?

Excavators

These can be used for both digging soil and compacting. While most people are familiar with the excavating attachment for excavators, there are also carrier-mounted compactor attachments that are well-suited for deep compaction.

Scrapers

These machines “scrape” the surface of the earth to prepare a site for construction projects. These level out the layers of the ground to the surface.

The four types of scrapers

  • Single-engine wheeled scrapers
    • These are the most common, using an apron to cover the load and stop the soil from flying out the top of the machine.
  • Dual-engine wheeled scrapers
    • These move soil a short distance. This machine has two engines, one to operate the front wheels and the other to power the rear.
    • They do well on rougher terrain since the two engines make the machine more powerful.
  • Elevating scrapers
    • These use an electronic or hydraulic elevator that raises and dumps material out. This is effective for evening surfaces
  • Pull-type scrapers
    • These aren’t motorized and require another machine to operate. They can also be towed to other machines. 
    • They’re excellent for wet, sandy, or soft soil. Because of their durability, they’re less likely to get stuck compared to their motorized counterparts. 

 

Rollers 

Do you know the machines that have what look like metal wheels with long widths? Yeah, we’re talking about those babies (large babies at that).

These come in a variety of styles and sizes with different options.

The six types of rollers

  • Cylindrical rollers
    • These use long cylindrical rollers to generate enough pressure to compact soil.
  • Sheepfoot roller
    • This uses a drum with rectangular-shaped protrusions.
    • They’re compact cohesive soils such as heavy and silty clays.
      • NOT effective for sandy soil
  • Pneumatic Tyred Rollers
    • These use four to six tightly spaced tires to compact cold-laid bituminous pavements, soft base course materials, or layers of loose soil. 
  • Smooth wheeled rollers
    • These used a large steel drum – along with one or two wheels in the rear of the machine – to consolidate stone soling, gravel, sand, hard core (like my music), ballast, and surface dressings. 
  • Vibratory rollers
    • These have one or two smooth surfaced wheels for compacting granular base courses.
  • Grid rollers
    • These have a cylindrical heavy steel surface that forms a grid with squire holes, providing high compact pressure. 

Smooth rollers

These machines are usually utilized in the final compaction step to provide smooth surfaces for construction. They use static pressure, sometimes in conjunction with vibration and impact to smoothen out and compact soil. 

Rammers

Not every soil compaction machine will be a behemoth meant for large sites. So don’t worry about an excavator in your backyard These can be used in confined spaces. 

Think of these like a jackhammer, but instead of using a chisel, it has a larger pad with a good amount of surface area that moves rapidly. 

This is perfect for foundation repair purposes. Before a pier underpinning is placed, the pier locations are excavated until they reach under your concrete footing. After everything is connected and put in place, the dirt is put back in and compacted layer by layer using a rammer.

Rammers are much less invasive compared to their large counterparts.

Soil compaction is important

As was said earlier, moisture is key when it comes to soil. You don’t want water to compromise anything under your home and cause damage. 

There may be voids with uncompacted soils moisture will break into or cause voids. Either way, it’s not a good time.

The whole point is to make the soils dense so water doesn’t break in or navigate through and cause erosion.

You also want to be sure the structure you have isn’t giving too much load for the soil to manage. It’s like a healthy relationship: You don’t want to be too overbearing (and vice versa). You want there to be a nice, healthy balance that doesn’t put unnecessary stress on your relationship. 

You’ve learned more about soil compaction. Now (figuratively) compact your brain – with more knowledge

You’ve learned about soil compaction, what happens if there isn’t proper compaction, what is used for soil compaction, and why it’s necessary for your home. Learn more about the importance of the soil under your home and foundation issues. 

Check how expansive soils cause foundation settlement and why clay soils fail

Are you asking yourself, “Should I walk away from a home with foundation issues?” Check out the highlighted article to direct you toward an answer. 

For additional questions, call Dalinghaus Construction at (877)360-9277.

WRITTEN BY

Brian Dalinghaus

Brian is one of the Co-Founders of Dalinghaus Construction. He has been in the foundation repair industry since 2005. During his career, he has been associated with helping over 4,000 homes and structures throughout California and Arizona.

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