How do I know if a slab is post-tensioned?

Common indicators include stressing pockets or tendon end caps visible at slab edges and building age and type. When in doubt, scan first.

Post-Tension Cable Scanning in Florida

Post tension tendon scanning before concrete cutting

PT Strike Prevention Tendon Path Mapping Clear No-Cut Zones

A severed post-tension tendon doesn't fail gradually — it releases stored tension energy instantly. The tendon can whip, the slab can crack along the cut line, and load redistribution can affect adjacent spans. Workers nearby are at serious risk. That's why PT cable scanning is a required step before any core drilling, saw cutting, or anchor work on post-tensioned concrete.

Why PT Slabs Are Different

Post-tensioned slabs use high-strength steel tendons — typically strands in a plastic sheath — running through the concrete under hundreds to thousands of pounds of tension per tendon. Florida has a large stock of PT construction: parking garage decks, high-rise residential floors, commercial podium slabs, and multistory office buildings all commonly use PT systems. Because tendons are continuous and under load, cutting one anywhere in the span can cause immediate localized failure.

The problem is that PT tendons are not always where the original drawings show. Tendons can be rerouted around penetrations, installed in non-standard patterns, or simply documented incorrectly. On renovation work, the original drawings may be unavailable. GPR scanning maps actual tendon locations — not assumed ones.

When to Use PT Cable Scanning

Before core drilling any post-tensioned slab
Before saw cutting trenches or expansion joints in PT floors
Before installing anchors in PT beams, columns, or decks
Before any penetration work on parking garage decks
Before renovation or retrofit work on PT high-rise floors
Any time you are unsure whether a slab is post-tensioned — scan first to confirm

How GPR Identifies Post-Tension Tendons

GPR reflects off the metallic components of PT tendon assemblies. A typical unbonded PT slab will show tendons running in two perpendicular directions — often at regular spacing. We scan the work zone, map the tendon run directions, and identify areas where tendons are more closely spaced, crossed, or bunched near supports.

We then mark the slab with paint showing the tendon runs, no-cut zones, and safer windows between tendons where the drill point can be adjusted if needed.

What GPR PT Scanning Cannot Confirm

The tension status of the tendons — GPR shows position, not load
Whether a tendon has already failed or been cut previously
Exact tendon size or strand count
The structural consequence of a proposed penetration — that requires the engineer of record

When the scan reveals that tendons run through a proposed core location, we help identify an alternate location or flag the area for engineering review before work proceeds.

What You Receive

Paint markings showing tendon run directions and no-cut boundaries
Identification of safer alternative core or anchor locations where tendon spacing allows
A verbal briefing with the foreman or drill operator before work starts
On request: photo documentation for engineering coordination or safety records

Schedule PT Cable Scanning Before You Core

Tell us the building type, target penetration areas, and whether drawings are available. Same-day and next-day scheduling in most Florida markets.

Request a PT Scanning Quote

Frequently Asked Questions

Common indicators include stressing pockets or tendon end caps visible at slab edges, plastic or metal end caps at the perimeter, and building age and type (most Florida high-rise residential and parking structures from the 1980s onward are likely PT). When in doubt, scan first.

Yes. After mapping tendon paths, we help identify locations where tendons are spaced further apart and a core hole can be placed between them. We do not approve structural penetrations — that requires the engineer of record — but we give your crew the field information to make a better decision.

If the scan shows tendon congestion throughout the planned work area, we flag the zone and recommend the location be reviewed by the structural engineer before drilling proceeds. This is always the right call.

Same-day or next-day scheduling is available for most Florida locations. Contact us with your project address and scope for confirmation.