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Can A Slab Leak Cause Foundation Problems? Yes

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Can a slab leak cause foundation problems? Unfortunately, the answer is yes. Slab leaks can cause foundation problems if they’re not promptly detected and repaired. The good news is that slab leaks are preventable.

In this article, you’ll learn the causes of slab leaks, signs of a slab leak, and foundation repair options for fixing damage caused by a slab leak.

What is a slab leak?

If you have a slab foundation, a slab leak is a plumbing leak under the concrete slab your home sits on. The problem with a slab leak is you can’t see the plumbing under the slab. That means you probably aren’t going to know right away if there’s a leak. However, out of sight shouldn’t mean out of mind.

Because a slab leak can cause significant damage to your home’s foundation, you should learn to spot the signs of trouble, catch the problem early, and avoid expensive repairs. One of the main cons of slab foundations is that the slab needs to be broken to access and repair a leaking pipe. In contrast, the plumbing in a crawl space foundation is easily accessed from under the house.

What causes a slab leak?

Slab leaks happen because pipes don’t last forever. They aren’t indestructible. Here are just a few reasons pipes spring leaks underneath a slab:

  • Pipes corrode, especially older cast iron pipes. If this happens, they will eventually spring leaks under the slab.
  • The pipes weren’t installed correctly. This happens from time to time.
  • The pipes were damaged during construction.
  • The pipes weren’t of high quality.
  • Water hammer.
  • Shifting soil puts pressure on pipes and causes them to move. Examples of this are expansive clay soil that swells as it soaks up moisture and shrinks as it dries out, earthquakes, frost heave, and soil erosion.

Can a slab leak cause foundation problems?

Yes, a slab leak can cause foundation problems. Here’s how that might happen in a foundation sitting on top of soil prone to erosion:

The slab leak causes water to saturate the soil, causing erosion. As the soil erodes, voids form under the foundation compromising its structural integrity. As the foundation settles into the voids, this stresses the house causing things like wall cracks, floor cracks, doors and windows that don’t open or close properly, etc.

If your home’s foundation was built on top of expansive clay soil, this could happen:

The slab leak releases excess moisture in the expansive clay soil, causing it to swell. As the soil swells, it pushes against the foundation and causes it to move slightly. As the home’s foundation moves, problems develop, such as cracks in walls and floors, trouble with doors and windows, and other issues.

In a nutshell, a slab leak causes soil movement under the foundation. This movement puts stress on the foundation and can eventually lead to serious foundation damage and expensive repairs. Therefore, homeowners should learn to spot the signs of a slab leak as early as possible.

For more information, see Foundation Settlement.

Slab leak signs

Warning signs of a slab leak include:

  • A water bill that’s higher than usual
  • A drop in water pressure
  • The sound of running water
  • Damp spots here and there on the floor
  • Moldy carpeting
  • Warm spot on floor.
  • An increase in pests as the insects are drawn to water.
  • Raised areas on the floor caused by heaving expansive clay soil
  • Foul odors either from mold growth or from a sewage leak under the house

Plumbing professionals have sophisticated methods for detecting slab leaks which we won’t go into here because we’re not plumbers. For more information on slab leak detection, contact an experienced plumbing professional near you.

Foundation repair after a slab leak

After your slab leak has been repaired, you’ll need to repair any foundation damage that occurred because of the leak.

Stabilizing the foundation to better withstand any future slab leaks is accomplished via a foundation repair technique called underpinning. The most common underpinning methods are,

  • Resistance push piers – Push piers are the most common method for stabilizing a foundation experiencing settlement. They are driven deep down into the soil until they hit the load-bearing strata. Once they’re in place, synchronized hydraulic jacks lift the building.
  • Helical piers – While corkscrew-shaped helical piers are usually used for new construction projects requiring a deep foundation, they’re also sometimes used for underpinning a foundation in distress. The torque necessary to turn them down into the soil determines their load-bearing capacity. Once they’re in place, hydraulic jacks raise the building.

Signs of foundation trouble

The following are general signs there might be a problem with your home’s foundation. These problems aren’t necessarily caused by a slab leak:

  • Windows and doors that don’t open and close properly
  • Unlevel floors
  • Ceilings and floors that are separating from the walls
  • Floor cracks – If the crack is limited to only one or two tiles, it was probably caused when something fell on the floor. However, a floor crack that runs wall to wall is a sign of foundation movement.
  • Wall cracks – Horizontal wall cracks are especially problematic. However, even vertical wall cracks should be checked out.
  • Bowed walls – Bowed walls are caused when the soil outside the basement wall gets saturated with water that can’t drain off. Hydrostatic pressure builds up and presses against the wall causing it to bow inward. Hydrostatic pressure can even cause a wall to crack.
  • Torn or wrinkled wallpaper – This might be a sign the wall behind the wallpaper is cracked.
  • Diagonal cracks that go from the corners of windows and doors toward the ceiling
  • Moldings that are pulling away from the wall or ceiling
  • Stair step cracks in brick or masonry
  • Chimneys and porches that are leaning away from the house.

If you notice any of the above or anything else that seems suspicious, contact a foundation repair contractor right away for an inspection.

If your Northern California home has experienced damage caused by a slab leak, contact us today for a free inspection and repair estimate.

Steve Egloff

Steve Egloff

Steve is the CEO at Bay Area Underpinning, a foundation repair contractor serving the San Fransisco Bay Area, California. Bay Area Underpinning was founded in 2005 with the goal of providing a cost-effective, engineered solution to foundation settlement problems with an emphasis on educating customers to make them feel comfortable with the various methods of foundation repair.

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