What is Hydrostatic Pressure?

What is Hydrostatic Pressure blog header

If you have water in your basement or bowing foundation walls, you've probably heard the term "hydrostatic pressure."

Hopefully, your contractor explained this to you appropriately. But while you might have an idea of what hydrostatic pressure is, it's important to know why it matters - especially when you're contemplating waterproofing or foundation repair projects that can greatly affect the value of your home.

What is hydrostatic pressure?

Hydrostatic pressure is the pressure that water exerts on a surface when it's standing still.

In the case of basements, when soil around the foundation becomes saturated with water, hydrostatic pressure builds up against the walls. This can cause cracks, bowing, and other damage to the foundation walls over time. 

Hydrostatic Pressure Graphic Showing Soil Pressure on Foundation Wall

Why does hydrostatic pressure matter?

At its most basic, hydrostatic pressure is just water pressure. In the case of waterproofing and foundation repair, it's water pressure pushing up against your foundation walls and floors. 

Because concrete is porous, the pressure outside your foundation will force water into your home. If the pressure becomes significant enough, the walls can bow or even collapse.

Hydrostatic pressure also varies by season. Rainy weather or a considerable spring thaw can significantly increase pressure, while drier seasons will see less pressure. Ultimately, there's no way to stop hydrostatic pressure from occurring, so homeowners must find a way to mitigate and redirect its effects.

Unfortunately, hydrostatic pressure is just one of the three main types of damage caused by wet foundation soils. And typically, one problem includes issues from the other two. The two other main issues to be concerned with if you have hydrostatic pressure affecting your foundation are:

Expansive, wet clay soil

While sandy soils remain stable as water passes through them, soils rich in clay change significantly based on their moisture content. When clay-type soils dry out, they shrink significantly. Sometimes, this shrinkage causes the ground to become covered with cracks, but after heavy rain, the cracks are gone, and the soil is fully saturated with water.

Because clay soil absorbs so much water, it expands during wet weather. Expansive clay soils can put enormous pressure on your basement or foundation walls. When the pressure exceeds what the wall can handle, the wall will begin to push inward.

What is Hydrostatic Pressure? - Image 3

Frost Heaving

In areas with cold winter climates, frost heaving can sometimes put enough pressure on foundation walls to make them fail. When water turns to ice, its volume increases by about 9%. If wet soil experiences a deep freeze, the wedging or heaving force that results can be extremely powerful. Frost heaving can put thousands of pounds of force against your foundation walls, causing cracks, bowing, and heaving.

How do you fix hydrostatic pressure in your basement?

Waterproofing and foundation repair techniques can help mitigate the effects of hydrostatic pressure and keep your basement safe and dry.

Waterproofing solutions, like sump pumps, below-floor drains, and baseboard drains, help when hydrostatic pressure increases. Instead of seeping water entering through your walls, it's redirected into these drain systems and is then pumped away from your home by the sump pump.

What is Hydrostatic Pressure? - Image 4

In addition, foundation repair options like wall anchors or braces help combat the inward pressure that causes foundation walls to bow or buckle due to water-saturated soils. These systems use the strength of carbon fiber and steel to help prevent future wall movement. 

What is Hydrostatic Pressure? - Image 5

Here at Thrasher Foundation Repair, we use a range of foundation repair solutions like:

  • GeoLock(R) wall anchor systems consist of galvanized steel Earth anchors embedded into the soil out away from your foundation wall. They are connected to steel wall plates with galvanized steel rods. Once installed, wall anchors will hold walls in their current position.
  • CarbonArmor(R) and ArmorLock(R) systems use carbon fiber reinforced polymers - a type of carbon fiber that is ten times stronger in tension than steel and designed specifically for basement walls.
  • PowerBrace system is designed to permanently stabilize your home's foundation. It supports basement walls and allows for straightening over time. This is done with brackets that are anchored to the basement floor and floor joists.

Thrasher is here to help

If you suspect that you might be seeing the effects of foundation wall failure, it's time to call in an expert like Thrasher Foundation Repair. In 45 years of business, we've seen it all and fixed it all.

We are the local experts for all your foundation repair needs. We offer warrantied solutions that permanently repair foundation issues.

If you're in our service area, contact us for a free, no-obligation foundation inspection today. By the time we're done, you'll know exactly what is causing your cracks, precisely what it will take to repair them permanently, and exactly how much it will cost.

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