Frisco, TX · Guide
Post-Tension Slabs: Adding Concrete Next to Your Frisco Home
Many Frisco homes sit on post-tension foundations. They work well on clay, but they change the rules for drilling, cutting and attaching new concrete.
01 — What this covers
The work itself
- What post-tensioning is
- Why builders use it in Texas
- How to tell if you have one
- Why drilling is dangerous
- Attaching patios and walks
- Garage anchors and lifts
- Polishing and coatings
- Who to call
02 — Detail
What a post-tension slab is
A post-tension slab has steel cables, called tendons, running through it inside plastic sheathing. After the concrete cures, the tendons are pulled tight and anchored at the edges, squeezing the slab together.
That compression makes the slab stiffer and helps it ride out the swelling and shrinking of Texas clay as one unit. It is widely used by production builders across North Texas.
The tendons stay under very high tension for the life of the house.
03 — Detail
How to tell if your house has one
Builders often stamp or mark the garage floor or a wall near it with a warning that the slab is post-tensioned. Look near the garage door or the door into the house.
The foundation plans or builder documents also show it. If you bought from the original builder, the warranty paperwork may mention it.
When there is no mark and no documents, a contractor or engineer can scan the slab to find tendons.
04 — Detail
Why you never drill blind
Cutting or drilling into a tensioned tendon can release its energy suddenly, which can injure people and damage the foundation. Repairs to a cut tendon are specialist work.
Even a cut that misses tendons can affect the slab if it is in the wrong place.
Any coring, saw-cutting or deep anchors should only happen after tendons are located with scanning.
05 — Detail
Patios and walks next to the slab
New patios and walks should be built beside the house slab with an expansion joint, not attached with dowels drilled into it.
The new concrete gets its own compacted base and steel, and the joint lets each part move independently on the clay.
This is standard practice for good contractors in Frisco, and it avoids any drilling into the foundation.
06 — Detail
Garage lifts, racks and equipment
Car lifts, storage racks and gym equipment often need anchors in the garage floor. On a post-tension slab, tendons must be located before drilling, and some installations need an engineer's input.
Freestanding or weighted options avoid anchors entirely where possible.
Tell the contractor what you plan to install so they can plan for it.
07 — Detail
Polishing and coatings
Grinding for polishing or coating prep removes only a thin surface layer, far above the tendons, so these finishes are commonly applied to post-tension slabs.
Saw cuts for decorative lines or new joints, and drilling for drains, are another matter and need the tendons located first.
A contractor familiar with Frisco homes will ask before starting.
08 — Detail
Foundation questions are a different specialty
Concrete contractors build and repair flatwork. If you see signs of foundation movement, such as wide cracks inside, sticking doors or a sloping floor, the right call is a foundation repair company or a structural engineer.
Post-tension foundations are repaired with specific methods, and anything involving the tendons should be handled by specialists who work with them.
How we work
Step by step
- 01
Check for a post-tension mark or documents.
- 02
Tell the contractor before planning work next to the house.
- 03
Scan to locate tendons if any drilling or cutting is needed.
- 04
Build new concrete beside the slab with an expansion joint.
- 05
Keep records of what was done.
What it costs
Scanning for tendons and engineering input add cost when drilling or cutting is needed. Building beside the slab usually avoids it.
Questions
Post-Tension Slabs and New Concrete — asked and answered
How do I know if my slab is post-tensioned?
Look for a warning stamp in the garage, or check the builder's plans.
Can I drill into my garage floor?
Not without locating the tendons first if it is post-tensioned.
Can a patio be attached to my house slab?
It should be built beside it with an expansion joint, not drilled in.
Can a post-tension garage floor be polished?
Yes. Grinding is shallow. Avoid saw cuts and drilling without scanning.
Who repairs a cut tendon?
Post-tension specialists and structural engineers, not general concrete crews.
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