Published September 14, 2026 • Slab Leak Repair Professionals
Post-tension slabs contain steel cables under enormous tension — cutting one is dangerous and structurally catastrophic. Here's how slab leak repair works safely on these foundations.
Many Rancho Palos Verdes homes built from the 1970s onward sit on post-tension slabs — concrete foundations reinforced with steel cables that are tensioned after the concrete cures. These slabs perform beautifully on the Peninsula's shifting soils. But they come with one hard rule for plumbers: never cut a tension cable.
A post-tension cable is a steel strand, often half an inch thick, pulled to roughly 33,000 pounds of tension and anchored at the slab edges. Cut one, and it doesn't just go slack — it can whip through the concrete with explosive force, injuring anyone nearby and permanently weakening the foundation. A severed cable also can't simply be patched; structural engineers must design a repair, and the slab never fully regains its original strength.
Standard slab leak repair — saw-cutting a square of concrete to expose the pipe — is therefore off the table unless the cable layout is known with certainty. On a post-tension slab, "I think the cables run that way" is not good enough.
The first step is always cable mapping. We use ground-penetrating radar or a pachometer (a rebar/cable locator) to trace every tendon in the work area before any cutting begins. Only then can we decide on a repair approach:
Look for small rectangular metal pockets along the slab edge or in the garage — these cover the cable anchor ends. Newer homes may have a warning stamp in the garage concrete reading "post-tension slab — do not cut or drill." If your home was built after about 1975 in RPV, assume post-tension until proven otherwise, and make sure any contractor you hire treats it that way.
We've repaired leaks in post-tension homes across Miraleste, Eastview, and the Peninsula Center area without disturbing a single cable. The key is equipment, mapping, and the discipline to choose rerouting when the slab says no. If you suspect a leak and your home is post-tension, call (833) 713-2101 — we'll map first and cut only when it's safe.
Talk to a Peninsula specialist — detection, honest advice, and upfront pricing.
Call (833) 713-2101Yes — safely. The standard approach is rerouting the line around the slab or tunneling beneath it. Direct through-slab cuts are only made after radar-mapping every cable in the area.
The cable can release violently, endangering workers and permanently weakening the foundation. Repairing a severed tendon requires a structural engineer and is extremely costly.
Check for metal anchor pockets along the slab edge or garage, or a warning stamp in the concrete. Homes built after the mid-1970s in Rancho Palos Verdes are commonly post-tension.
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