Can a Post-Tension Slab Be Repaired? What to Ask Before Hiring a Contractor

What makes this slab different?

Post-tensioning uses steel tendons that are stressed after the concrete has developed the required strength. The force places compression into the concrete as part of the structural design. That system needs to be considered when planning work that could affect the slab or its reinforcement. It is not a reason to assume that an existing foundation is beyond repair.

Start with the records you have: original plans, builder information, previous engineering reports and repair documents. A warning stamp or other visible marking may be a useful clue, but the contractor should establish the foundation construction using appropriate information and investigation. Do not make an exploratory cut or hole to try to identify the reinforcement yourself.

Separate the support question from the tendon question

An uneven floor or changing crack can prompt a foundation assessment, including observations and relative elevation measurements. Those findings help evaluate the foundation's shape and the need for further investigation. They do not, by themselves, establish that a tendon has failed. The proposed repair should make clear whether it addresses support beneath the slab, concrete damage, the post-tensioning system, or more than one concern.

The Post-Tensioning Institute describes evaluation and repair of existing post-tensioned structures, including structures with tendon damage. That establishes that repair methods exist; it does not establish the correct method for your home. A specialist evaluation may be needed when there is a tendon or anchorage concern. Ask who will assess that question and how the findings will be incorporated into the foundation plan.

Ask how access work will protect the existing system

Coring, drilling or cutting into a post-tensioned structure can damage tendons. If a repair needs a floor opening, the contractor should explain how the work area and existing reinforcement will be investigated, how the opening will be planned and who authorizes the procedure. An approximate cable location or a general promise to be careful is not a complete access plan.

The same coordination matters if a plumber or remodeling contractor will work on the slab before or after foundation repair. Share the foundation information with everyone whose work could penetrate it. Avoid removing or disturbing exposed tendon or anchorage components. If you have noticed damage in such an area, describe it when arranging the evaluation and leave it for qualified professionals to examine.

Five questions that make a proposal easier to assess

A contractor should be able to describe the relevant experience and the limits of its own scope. You are looking for clear responsibility across the project, especially when the foundation contractor, an independent engineer and a post-tension specialist have different roles. Ask for those responsibilities in writing before the work is scheduled.

• What evidence identifies the foundation construction and the condition that needs repair?
• Who will evaluate any suspected tendon or anchorage damage?
• Who prepares the engineering repair plan and establishes adjustment limits?
• How will planned access openings and any other slab penetrations be evaluated and approved?
• What inspection and completion documents will record the work performed?

How the foundation repair discussion fits together

Pro-Tech uses drilled, steel-reinforced concrete piers for appropriate slab support repairs. The piers cure before adjustment under the independent structural engineer's guidelines. For a house with a post-tension slab, the assessment and repair planning must account for that construction before determining suitability, locations and access. The presence of post-tensioning is information the team needs at the start.

A foundation support proposal should not be read as an offer to repair or restress tendons unless that work and its qualified provider are specifically identified. Clarify any separate specialist work and how it affects scheduling. Also establish who handles disturbed flooring and other finishes so the full project can be planned around the agreed structural sequence.

Start with the slab's records and the changes you see

You do not need to decide whether the problem is a tendon or the ground beneath the foundation before making contact. Explain the visible concern, when you noticed it and whether there has been earlier foundation work or slab cutting. Send available records with the property information, and identify any specialist findings already in hand.

Request Pro-Tech's no-cost initial in-person foundation inspection to begin that conversation. Tell our staff that the house has, or may have, a post-tension slab. They will confirm the address is within our service area and arrange the visit; any separate engineering or specialist service should have its own clearly explained scope and terms.