How a plumbing leak damages a foundation
A South Florida slab rests on compacted sand. Water moving through that sand carries fine particles with it, a process called washout or soil erosion, and leaves a void under the concrete. A slab spanning a void has lost part of its support, so it cracks and settles into the gap.
Drain leaks are often the most damaging, because every shower, flush and load of laundry sends wastewater into the same spot. Pressure-side leaks run constantly and keep the fill saturated. Either type, left for months, can move enough sand to affect the structure above it.
Warning signs of a leak under your foundation
- New cracks in floor tiles or across the slab.
- Diagonal cracks at the corners of doors and windows.
- Doors and windows that begin to stick or will not latch.
- A gap opening between baseboards and the floor.
- A section of floor that feels lower or slopes.
- Damp or discolored flooring near an interior wall.
- Water pooling along the outside of the foundation without rain.
- A sewer odor inside the house, which points to a drain leak.
How we repair foundation leaks
Identify the leaking system
A pressure test checks the supply lines and a hydrostatic test checks the drains, so we know which system is leaking. See water leak detection.
Locate the failure
Acoustic listening, thermal imaging or a sewer camera with a locating transmitter pinpoints the break.
Choose the access
We reach the pipe through the slab at the marked point or tunnel from outside to protect finished floors.
Repair or replace the pipe
Damaged copper is replaced with copper or PEX, and failed cast iron is replaced with PVC.
Test the repair
Supply lines are pressure tested and drains are water tested before anything is covered.
Restore support
We compact the fill in the excavation, patch the concrete and report any voids or settlement we saw.
Plumbing repair and structural repair are different jobs
We are plumbers. Our job is to find the source of the water and stop it, and stopping the leak always comes first, because any structural repair made while a pipe is still leaking will fail. When settlement is already visible, a licensed structural engineer should assess the foundation, and a foundation contractor may fill voids or stabilize the slab. We share our leak location and findings with your engineer so both repairs are planned together.
Drain line leaks under older Delray Beach homes
Homes built before the mid-1970s commonly have cast iron drain lines under the slab. Cast iron corrodes along the bottom of the pipe, where wastewater sits, until the pipe wall channels through or cracks. Roots and settlement can also separate the joints. Repair options include replacing the failed section with PVC, replacing the full under-slab drain system, or lining the existing pipe where its shape allows. A hydrostatic test shows whether the drains hold water, and a camera inspection through the sewer line shows where they fail.
Foundation Leak Repair questions
Will fixing the leak fix my foundation cracks?
Fixing the leak removes the cause, so the damage stops getting worse. Existing cracks and settlement do not reverse on their own, and a structural engineer can tell you whether they need repair.
How do I know if the leak is from a supply line or a drain?
If your water meter moves with every fixture off, a supply line is leaking. If the meter is still but you have signs of water under the floor or a sewer odor, the drains are the likely source and a hydrostatic test will confirm it.
Can a foundation leak cause mold?
Yes. Moisture from under a slab wicks into flooring, baseboards and the bottom of drywall, and mold can begin within a day or two in Florida humidity. Stopping the leak and drying the affected areas quickly prevents it.
Does foundation leak repair need a permit in Delray Beach?
Replacing under-slab piping generally requires a plumbing permit and inspection. When your repair needs one, we obtain it before the work starts.