Tile Removal Over a Post-Tension Slab: What Has to Be Known First

Before tile comes off a post-tension slab, you need to know that the slab is post-tension and that nothing in the removal will cut, drill or grind into it. Taking tile off the surface is normal work; damaging the steel cables inside the concrete is a serious structural and safety problem.

Many homes in the Las Vegas valley are built on post-tension slabs, so this comes up more often than people expect. Here is what it means for your tile project.

What a post-tension slab is

A post-tension slab is a concrete foundation with steel cables, called tendons, running through it. After the concrete cures, those cables are pulled tight and anchored at the edges of the slab. The tension helps the slab resist cracking and movement, which is one reason the method is popular on the soils found around the valley.

The important part for homeowners is simple: those cables are under very high tension. If one is cut or badly damaged, it can release suddenly, and the slab can lose some of the support it was designed to have. Repairing it is specialized work.

How to know if your home has one

Many post-tension homes have a stamp, sticker or plaque somewhere — often in the garage, near the electrical panel or in a closet — warning not to cut or drill into the slab. Your home's plans or builder documents may also say so. Sometimes you can see the anchor pockets along the edge of the foundation outside. If you are not sure, assume it may be post-tension until you know otherwise.

Tell us what you know when you call. If you have found a warning label, that is useful information.

Tile removal itself is surface work

Taking off tile and thinset is work on top of the slab. Done properly, the tools are breaking the bond between the tile, the mortar and the concrete surface — not going into the concrete. That is why tile removal over a post-tension slab is routine when the crew knows what it is working on.

Where care is needed is anything that goes deeper. Aggressive grinding in one spot, chiseling into cracks, drilling anchors for fixtures or cutting the slab for plumbing all need to be planned with the tendons in mind.

When the job goes beyond the surface

Sometimes a tile project turns into more than a tile project. A leak shows up once the floor is open. A new shower drain needs to move. A kitchen island needs a new plumbing or electrical line. Any of these can mean cutting into the slab.

On a post-tension slab, that cutting needs the tendons located first, typically by scanning, and the cut laid out to avoid them. If the location conflicts with a cable, the plan changes — the cut moves, or an engineer is brought in to say what is acceptable. That is not a step we skip or guess on.

Cracks, patches and leveling

When tile comes up, the slab underneath sometimes shows cracks. Fine shrinkage cracks are common in concrete and are not necessarily a sign of a problem. Wider cracks or areas that have moved deserve a closer look, and if something looks structural, the right person to judge it is a structural engineer or the builder, not the demolition crew.

For the new floor, the slab may need patching or leveling. Those products go on top of the concrete and do not involve cutting into it, but they should still be applied by someone who understands the slab.

What drives the scope

The same things that affect any tile removal apply here: the type of tile, how much thinset is under it, whether it was set in a mortar bed, how clean the slab needs to be for the new floor, and access for equipment and debris. On a post-tension slab, the additional question is whether any work will go into the concrete, because that adds locating and planning. We will not put a number on it without seeing the job; we will explain what affects it and give you an exact quote after we walk the floor.

Dust and noise

Tile removal is loud and it is not dust free, regardless of the slab type. We contain the work area and clean up before we leave, and we will talk with you about what to move out and how to prepare the house.

A note for property managers

If you manage rental homes or condos, it is worth keeping a record of which properties have post-tension slabs. It saves time on every future flooring turnover, plumbing repair or remodel, and it gives any contractor the information they need up front. Share that record with us when you call, along with any past repair history on the slab, and we can plan the work more accurately from the start.

Questions to ask any contractor

Do you know whether my slab is post-tension? What tools will you use, and will anything cut or drill into the concrete? If the job turns into a slab cut, how will you locate the cables first? A contractor who has clear answers to those questions is one you can trust on this kind of floor.

Our tile and stone removal page explains how we take tile and thinset down to a clean slab, and our concrete saw cutting and removal page covers slab cuts when a project needs one. We work across Las Vegas, Henderson, North Las Vegas, Summerlin, Spring Valley, Paradise and Enterprise. Call us for a free estimate and an exact quote.