Introduction
A post tension slab carries every structural calculation you made under the assumption that every tendon is intact, stressed, and continuous. When a cable is accidentally cut by a plumber's saw, a demo crew's concrete cutter, or a contractor who misread the drawings, that assumption collapses immediately. In experience across Dallas-area projects, the first 24 hours after a severed PT tendon determine whether the repair is a controlled $800 fix or a multi-thousand-dollar slab replacement discussion.
The consequences compound fast. A single severed unbonded tendon in a two-way flat plate can release up to 26 kips of prestress force in both directions from the cut point, depending on tendon length and stressing configuration. Left unaddressed, the unbalanced load redistribution triggers cracking, increased deflection, and, in the worst case, punching shear vulnerability at nearby column-slab connections. Some contractors pour a patch over a visible tendon end and walk away — that is not a repair, and it will not hold.
This guide gives you the exact protocol we follow on-site when a tendon is cut: what to stop, what to document, and which repair path is structurally defensible. For a broader diagnostic framework, read our article on 5 warning signs your post-tension slab needs immediate expert repair and how much it costs.
Step 1 — Stop Work and Secure the Zone
The moment a tendon is cut, stop all trades in the affected bay. This is non-negotiable. An unbonded PT tendon that has just lost its anchor condition can retract with significant stored energy, particularly on longer runs where the free length exceeds 40 ft.
Establish a 10 ft minimum exclusion zone around the cut location and the nearest anchorage pocket. Place a spotter at each end until the tendon movement has arrested. Then photograph everything before anyone touches the debris: the cut face, the pocket condition, the reinforcing steel around the cut, and the slab surface in both directions.
Immediate On-Site Documentation Checklist
- Tendon identification number from the PT shop drawings (if available)
- Cut location: bay coordinates, distance from nearest support, and floor level
- Estimated tendon length and stressing end location
- Direction of retraction and estimated retraction distance
- Condition of adjacent tendons within 24 in.
- Date, time, trade responsible, and name of site supervisor present
Step 2 — Assess the Structural Impact Before Calling a Repair Crew
Not every cut tendon carries the same structural consequence. The severity depends on the tendon's position within the two-way or one-way system, its contribution to balanced load, and whether the system has inherent redundancy. Before you call a repair contractor, you need at minimum a conceptual assessment from a structural engineer reviewing the original PT design documents.
We evaluate cut-tendon impact by reviewing three primary factors: the number of tendons crossing the cut section versus what is required by ACI 318-19 Section 8.6.2.3 for minimum average prestress of 125 psi in each direction; the tendon's proximity to a column strip versus a middle strip (column-strip tendons carry the majority of the unbalanced moment transfer at supports); and the eccentricity of the remaining prestress relative to the slab neutral axis along the affected span.
Quick Severity Classification We Use in the Field
| Severity | Condition | Immediate Action Required |
|---|---|---|
| Low | Middle-strip tendon, >3 adjacent tendons intact, no visible cracking | Document and schedule repair within 7 days |
| Moderate | Column-strip tendon OR middle-strip with 2 or fewer adjacent intact tendons | Restrict live load in bay, repair within 48 hours |
| High | Column-strip tendon adjacent to support, visible cracking, or multiple tendons cut | Shore the bay immediately, halt occupancy, notify EOR |
This classification is a field screening tool only, not a structural determination. Decisions involving shoring, occupancy restriction, or slab adequacy require review by the engineer of record (EOR) or a licensed structural engineer with access to the original design files.
For a detailed cost breakdown depending on severity and Texas region, use our post-tension slab repair cost calculator.
Step 3 — Choose the Right Repair Technique
There are three primary repair methods for a severed unbonded PT tendon. The right choice depends on accessibility, retraction distance, and whether both cut ends are recoverable.
Repair Option A: Inline Coupling Splice (Best for Accessible, Short Retraction)
When the tendon retracts less than 8 in. and both ends remain in an exposed pocket or can be reached by saw-cutting a 12 in. chase, an inline mechanical coupler is the cleanest repair. The existing strand is re-tensioned through the coupler after installation, and the pocket is regrouted with non-shrink material. This approach preserves full tendon continuity and restores the original prestress level.
What Worked On-Site
On a two-story Dallas residential slab, a plumber cut a tendon at mid-span. The retraction was 4 in. We exposed both ends with a 10 in. chase, installed a PTI-compatible inline coupler, restressed to the original 33 kips using a hydraulic mono-jack, and regrouted the pocket. Total on-site time: 6 hours. Total cost: approximately $850 for labor and materials.
What Did Not Work
On a different project with a retraction of 11 in., the contractor attempted the same inline splice without first confirming the free length remaining on each side. The coupler could not develop the full prestress because the bonded zone was too short. We had to abandon the splice and move to Option C.
Repair Option B: New Tendon Overlay (For Major Retraction or Inaccessible Ends)
When retraction exceeds the serviceable length for an inline coupler, or when one end has retracted past a support and cannot be recovered without major demolition, a short supplemental tendon can be installed parallel to the damaged one. This requires a saw-cut chase, new anchor plates, and re-stressing from a temporary pocket. The new tendon must be designed to replace the prestress contribution of the severed tendon, not simply added on top of the existing system.
This option carries a higher cost: typically $1,800 to $4,500 depending on slab thickness, span, and access difficulty. For regional estimates in the Dallas-Fort Worth area, read our article on the average cost per square foot for post-tension slab repair.
Repair Option C: Passive Reinforcement Supplement (Interim or Permanent for Low-Severity Cases)
In low-severity cases — middle-strip tendons with multiple adjacent intact cables and no serviceability distress — the EOR may approve a supplemental passive reinforcement scheme using epoxy-anchored rebar or carbon fiber reinforced polymer (CFRP) strips bonded to the slab soffit. This approach does not restore prestress; it provides passive reserve capacity to maintain load path integrity at serviceability loads.
CFRP repairs in Texas typically run $60 to $110 per linear foot installed, making them cost-effective for slabs where access for restressing is physically impractical. However, we only recommend this route after explicit written confirmation from the EOR that the loss of prestress is acceptable within the serviceability and strength limits of the original design.
Step 4 — Execute and Document the Repair
The repair itself is only half of the deliverable. A post-tension slab repair that is not documented in writing has no engineering standing: not for future inspections, not for insurance claims, and not for future structural modifications. We require the following documentation for every PT repair we oversee:
- Pre-repair GPR scan confirming tendon positions of adjacent cables
- Photographs of the exposed tendon ends before and after surface preparation
- Coupler or splice product data sheet and certification to applicable PTI DC80.3 or ASTM A416 requirements
- Gauge readings at stressing jack: initial seating, full stress, and lock-off pressure in psi
- Elongation measurement versus calculated theoretical elongation (acceptable tolerance per PTI: plus or minus 7%)
- Grout product data and grouting date/time
- Signed inspection log by responsible party on-site
For a complete step-by-step execution guide, including elongation calculation methodology and pocket grouting specifications, refer to our dedicated article: emergency repair: step-by-step guide to fixing a severed post-tension tendon.
What This Costs on a Real Project and What Drives the Variation
The cost range for post-tension cable repair work in Texas spans from under $1,000 for a straightforward inline splice to over $15,000 for multi-tendon damage requiring shoring, GPR scanning, and EOR involvement. The table below reflects realistic market rates we have observed on Dallas-area projects.
| Repair Scenario | Typical Cost Range (DFW) | Key Driver |
|---|---|---|
| Inline coupler splice, single tendon, <8 in. retraction | $700 - $1,200 | Access and labor time |
| New supplemental tendon, single bay | $1,800 - $4,500 | Chase cutting and re-stressing |
| CFRP soffit reinforcement, per 10 linear ft | $600 - $1,100 | Material cost and epoxy prep |
| Shoring, GPR scan, and EOR review package | $2,500 - $6,000+ | Scope and engineering hours |
| Multi-tendon damage, post-repair slab analysis | $8,000 - $15,000+ | Extent of damage and documentation |
For a site-specific number based on your damage type and Texas region, use our post-tension slab repair cost calculator. For broader context on what regular inspection prevents, see our article: do post-tension slabs require regular professional inspection.
Frequently Asked Questions
Can you repair a post-tension slab after a tendon is cut, or does the slab need to be replaced?
In most cases, a single severed tendon can be repaired without replacing the slab. The feasibility depends on retraction distance, tendon accessibility, and how many adjacent cables remain intact. Full slab replacement is rarely required unless multiple tendons are cut within the same column strip and the damage triggers a punching shear deficiency at a support.
How do I know if a cut tendon is an emergency requiring shoring?
Shore the bay if: the cut tendon is in the column strip within one effective depth (d) of a column or wall support; two or more tendons in the same band are damaged; or visible cracking has developed along the tendon path or at a nearby support. When in doubt, shore first and assess after. The cost of unnecessary shoring is trivial compared to the liability exposure of an unshored slab with compromised prestress.
Does a PT tendon repair need to be inspected by a licensed engineer?
Texas does not have a single statewide code section that mandates licensed-engineer sign-off on all PT repairs, but the original building permit, owner requirements, and lender insurance policies almost always require it for structural modifications. Any repair that restores prestress — meaning a coupler splice or new tendon installation — should have at minimum a written review by the EOR confirming that the repair design matches or exceeds the original design intent. [VERIFY applicable local jurisdiction requirements for your specific project.]
What is the average cost to repair a broken post-tension cable?
Based on project experience in the Dallas-Fort Worth market, a single-tendon repair using an inline coupler splice typically runs $700 to $1,200 all-in for a residential or light commercial slab. That figure rises to $1,800 to $4,500 for scenarios requiring a supplemental tendon installation. Engineering review, GPR scanning, and documentation are typically billed separately and can add $2,500 to $6,000 for more complex cases.
Can a general contractor perform a post-tension tendon repair, or does it require a specialty subcontractor?
PT tendon repairs involving mechanical couplers and re-stressing require a specialty PT subcontractor with hydraulic stressing equipment, calibrated jacks, and personnel trained in PTI elongation procedures. A general contractor cannot perform the restressing operation without that equipment and documentation capability. Passive CFRP repairs can technically be installed by a specialty concrete contractor, but the design of the repair must still originate from or be reviewed by a structural engineer.
Work With TensionOne on Your PT Slab Repair Project
Tendon Cut on Your Project? Let's Address It Properly.
When a tendon is cut, the time between discovery and a defensible engineering response matters. We provide structural review, repair design drawings, calculation notes, and on-site stressing oversight for post-tensioned slab projects across Texas. Our deliverables are formatted for permit submission and EOR review.
If your project requires preparation of repair drawings and calculation notes for a damaged post-tension slab, submit a project inquiry through our freelance services page. We typically respond within one business day with a scope confirmation and fee estimate.
- Tendon layout review vs. as-built conditions
- Prestress loss calculation at cut location
- Coupler splice or supplemental tendon design
- Elongation calculation sheet
- Repair detail drawings (AutoCAD/PDF)
- Signed calculation notes for permit or EOR coordination
Related Articles from TensionOne
TensionOne provides structural engineering support services. All deliverables are prepared for review and use by a licensed Professional Engineer. TensionOne does not provide PE-stamped documents directly.
References: ACI 318-19: Building Code Requirements for Structural Concrete, American Concrete Institute. PTI DC80.3.3: Specification for Unbonded Single Strand Tendons, Post-Tensioning Institute. ASTM A416: Standard Specification for Low-Relaxation Seven-Wire Strand, ASTM International.
About the Author: Joseph is a Civil Engineer and Founder of TensionOne LLC, specializing in post-tensioned slab design, structural calculations, and tendon layout for projects across Texas and internationally. All content is based on field experience and published engineering standards. No PE-stamped structural guarantees are expressed or implied by this article.
