Water Management Part 2: Proper Soils

By Ben Golden

We are now into part 2 of the water management series. This blog will be discussing how the soils around your home affect the longevity of your foundation. It is best to address soils before construction even begins to avoid potential damage and high soil replacement costs.
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Foundation Backfill:

Wet basements are one of the most detrimental construction defects out there. This is an issue that can be avoided entirely if the proper steps are taken when digging a home’s foundation. There is much debate around this topic, but we know through experience how important it is to have correct soils around the foundation. Backfilling your foundation with the existing soils on your property can cause problems. Depending upon the type of existing soil, you may end up with wet basement issues, cracking, buckling, or other structural issues.

 

Water Management
*Foundation Cracking and movement from improper soils and poor water management

 

For example, the Midwest region (Minnesota, Wisconsin, Dakotas, Iowa) is filled with both organic and alluvial clay. These soils are extremely aqueous. They hold moisture and will never dry out.

 

Water Management
*Wet clay soils pictured above

 

This is a problem for 2 reasons:

  1. Hydrostatic Pressure: Specifically, during spring months, clay soils will become completely saturated with water. Hydrostatic pressure increases with ground depth (read Water Management Part 1 to learn more about Hydrostatic Pressure Here (tech bear, please link to previous water management blog)). In a standard 9-foot foundation, there could be almost 600 pounds of pressure pushing inward on the base of the foundation. This could cause cracking, buckling, or other structural problems.
  2. The Freeze/Thaw Cycle: The freeze thaw cycle can wreak havoc on a foundation with incorrect soils. If you have wet soils going into winter, that moisture will freeze and soils expand which puts a lot of pressure on the sides of your foundation. Homes are designed to handle vertical loads, but not horizontal weight pushing in on the foundation. Ultimately, cracking, shifting walls, and other structural issues can arise.

If you are building a home in the Midwest region, the smartest move you can make is to fill around the foundation with correct soils. If you do not, you may start seeing signs of failure within only 5-10 years.

 

Wet Soil
*Wet clay soils being removed

What types of soils should you be using?

You now know that simply using the existing soil on your property as backfill around your foundation is NOT always a great idea. So, what soils should you be using? The answer is, compactible aggregate soils. This could be anything from recycled asphalt and concrete (con-bit), to red rock gravel, or equivalent. These soils do NOT become saturated with water the way clay soils do and therefore are a much healthier and sustainable option for backfill. However, in order for these soils to be effective, they must be compacted correctly. Proper install is just as important as proper soils themselves.

 

Compacted Aggregate Soil
*Compacted aggregate soil correction pictured above

What if the damage has been done?

Above, you learned about the proper soils for your new construction build, but what about an existing structure? If you have read this far, you may be noticing symptoms of poor water management around your own home. If you are noticing cracks, buckling, shifting walls, etc. then it may be a case of improper soils in conjunction with bad drainage (coming soon in Water Management Part 3) and inadequate roof drainage systems. It’s important to get a professional’s opinion. Juno Construction can do such an inspection for you.

If, in fact, your home does need to have a soil correction performed, there are ways to achieve this. It is not a cheap fix, but it is a permanent one. The soil around your home will need to be fully dug up and replaced with compatible aggregate soils. Along with this, the grading needs to be addressed. Water Management Part 3 will discuss this in detail.

 

*Soil correction being performed

 

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