What is a post tension slab?
Concrete slabs that have post tension cables in them that have been pulled extremely tight, are referred to as “Post Tension Slabs.”
Most concrete garage floors fall into one of three categories:
- A concrete slab with no reinforcement in it; neither rebar or post tension cables
- A concrete slab with steel rebar in it; at times referred to as a slab with steel reinforcement
- A concrete slab with steel reinforced cables in it; often called a post tension slab
Older homes may have neither rebar nor post tension cables in the slabs. When a home does not have reinforcing rebar or a post tension slab, then the concrete tends to crack a little more than if reinforced. The cracks that occur may have one side higher than the other and the cracks may be wider than those in reinforced slabs. Homes without reinforced slabs also tend to have more cracks in the concrete and in any tile floors. Putting a slip sheet under the tile floor when installed will help to reduce the cracking.
Post tension reinforced concrete slabs can often be identified by a sign stamped in the concrete garage floor or by a plastic warning sign placed on the garage wall. The reason for the warning sign is to alert the owner not to cut or drill into the concrete without having a professional contractor do the cutting or drilling – it’s a safety thing, because if one cuts a post tension cable, it may whip upward and injure the person.
From a structural standpoint, a reinforced concrete slab or a post tension slab, is better than a non-reinforced slab, however, families live quite happily in homes that are built either way.