5 Causes of Slab Leaks

by | Mar 24, 2021

If you live in Florida, chances are your home is built on a slab foundation. Because soil here doesn’t shift due to freezing and thawing during the winter, a slab foundation actually serves as a cost-effective base for your home. They are also durable, pest-resistant, and better insulated than a basement or crawlspace.

A slab foundation is constructed by pouring concrete into a frame about 4” to 6” deep that is then smoothed over and allowed to cure. Contractors reinforce the concrete by installing a steel rebar frame, which is like a wide wire mesh, that gives the slab more support. Once the slab is dry, the frame is removed and the rest of the home can be built on top.

One disadvantage of a slab foundation, however, is that the plumbing and ventilation lines that would normally run through a basement or crawlspace must be installed before the concrete is poured. This equipment is usually laid in a gravel bed that sits underneath the slab, which allows moisture to drain away from the foundation.

Because of this, it can be difficult to repair breaks or other problems with pipes and vents once the foundation has been poured. Recognizing that you have a slab leak is only the first step to getting it fixed. Once you discover a leak, it’s important to understand why it occurred in the first place.

Here are five reasons why your home may have developed a slab leak.

Signs That You May Have a Slab Leak

By the time you notice a slab leak, there’s a good chance that the problem has occurred for some time. That’s why it’s important to call a qualified plumber as soon as you notice any of the following:

  • Damp spots that never seem to dry
  • Decreased water pressure
  • Mold that develops under your carpet or flooring
  • Standing water or soft spots alongside of your home’s foundation
  • Water sounds, including drips and trickles, even when the water’s off
  • An unusual increase in your monthly utility bill

If you notice any of these symptoms, you should have a plumbing technician come out to inspect your home. Even if it’s not a slab leak, these signs can all point towards trouble with your plumbing.

1. Poor Construction

Installing plumbing for a home with a slab foundation is both difficult and complicated. Because the initial plumbing lines must be run before the foundation can be poured, plumbers must be as accurate as possible with all of their measurements, because it’s extremely hard to go back and fix things once the concrete has cured.

In addition to misplaced lines, you may run into issues if your plumber uses low-quality materials, which are more likely to become dented, kinked, or otherwise damaged during construction and afterward. Some metal pipes, like copper, are also vulnerable to chemical corrosion, which could cause them to weaken over time.

When a pipe springs a leak, even if it’s only a millimeter wide, it can immediately begin to affect your foundation. If the leak isn’t repaired, it will continue to grow until the pipe is replaced.

2. High Water Pressure

Most people think that high water pressure is a good thing, and to a point, they’re correct. However, if the water pressure becomes too high, there’s a good chance it could cause significant damage to your pipes. Most plumbing is only rated to withstand a certain degree of water pressure; once you exceed that level, there’s no guarantee that your pipes will be able to withstand the force of water flowing through them.

There are a number of reasons why your water pressure may be too high. On one hand, it may be a construction issue, like a kinked pipe to a shift in the soil beneath the home that’s been pinched to a narrower diameter. On the other hand, it could be a municipal issue, in which water pressure has been increased to meet an exceptional demand.

3. Shifts in Your Foundation

The ground beneath a home is not always static and unmoving. In fact, it’s more like a living organism, responding to the environment — sometimes in unpredictable ways. While a great deal of work goes into preparing a site for a slab foundation, unforeseen events can cause the soil beneath a slab to shift. 

There are a number of natural forces that can shift your home’s foundation. Depending on where your home is located, earthquakes can significantly change the structure of the ground below your foundation. Underground streams can also cause the soil beneath your home to degrade, eventually causing your slab to shift.

Over time, weather can lead to soil erosion, especially if your home doesn’t have adequate drainage for moisture. Periods of heavy rain, significant snow run-off, and unexpected periods of soil freezing and thawing can all cause the soil around your foundation to erode, potentially shifting your entire foundation. 

These shifts can put unexpected pressure on pipes, which are not designed to withstand that kind of weight. This can lead to pinching and kinking, as well as significant leaks that could undermine your home’s foundation. 

4. Poor Water Quality

Keeping tabs on your home’s water quality is one of the most overlooked aspects of plumbing maintenance. Water quality sometimes referred to as “hardness,” is measured on the pH scale that goes from 1 to 14, with 7 being neutral. When water shifts towards 1 on the pH scale, it’s considered to be acidic, or “hard,” while a rating on the other end of the scale means that the water is basic, or “soft.”

Ideally, you want your home’s water to remain between 6.5 and 8.5. Although the best measure is a home litmus test, another way to tell that your water is too acidic is if you find blue-green residue in your sink or shower or if you smell chlorine-like odors. If your water is out of balance, it could severely—and permanently—damage your pipes.

5. Time

It’s not uncommon for pipes to wear out over time. There are a number of reasons why this can happen. Water moving through pipes is actually quite abrasive, and as time passes, it wears away material from the pipe, until eventually, the pipe springs a leak. Corrosion from acidic water can also contribute to weakened pipes, even with proper pH maintenance.

Another factor that leads to pipe damage is the friction that occurs with everyday use. As you turn your water on and off, the pipes in your plumbing system will move or shake slightly with changes in pressure. If it happens to rub up against another object, such as a rock, another pipe, or the foundation itself, this friction can cause a leak to erupt. This is especially true for hot water pipes, which become softer as hot water passes through them.

Solving a Slab Leak

Once you determine that you have a slab leak, you can investigate repair options. Depending on the location of the leak, your plumber may be able to reach the pipe in order to fix it. If that’s not the case, there are a number of techniques for re-installing a pipe at the location of the leak or installing an epoxy-soaked sleeve to seal the leak from the inside of the pipe.

When you suspect that you may have a slab leak in your home, call a licensed and insured plumber, like the team at I Need a Plumber & Air Conditioning. Our experienced technicians will get your slab leak under control fast.