Delamination is when a coating separates from the concrete or from the layer beneath it. It shows up as peeling, flaking, or hollow-sounding spots. Common causes are poor prep, contamination, and moisture. A delaminating coating usually has to be removed before recoating.
Why Delamination Matters for Your Floor
A coating only works as long as it’s stuck to the floor. When it delaminates, you get peeling sheets, flaking edges, and patches that sound hollow when you tap them or drag a set of keys across them. In a garage, hot tires and road salt make loose areas spread fast.
Delamination is also a warning sign. Something kept the coating from bonding, and that same problem will ruin a new coat if it isn’t fixed first. Painting over peeling is like putting a new bandage over a dirty one.
What Causes Coating Delamination
Most coating delamination comes down to one of these:
- Surface prep. A coating needs some texture to grip, a bit like sanding a glossy wall before painting it. Ask your installer how they’ll prepare the concrete surface profile.
- Contamination. Leftover residue on the slab, like oil or an old sealer, can keep a coating from bonding. Ask how they’ll check for and remove it.
- Moisture in the slab. Water vapor rising through the concrete can cause bubbling, softening, and delamination under floor coatings, including epoxy.
- Problems between coats. If a film like amine blush forms on a coat before the next one goes on, the layers can split apart.
Coating Delamination vs. Concrete Delamination
The word gets used for two different problems. Coating delamination is the finish coming off the slab. Concrete delamination is the concrete itself splitting: thin layers of the slab surface separate from the concrete below, usually because the surface was finished too early when it was poured.
Concrete delamination is different from spalling, which is chipping or flaking that’s often caused by freeze-thaw cycles and deicers. Both leave rough, broken patches, and both have to be ground off down to solid concrete before any coating goes on.
What to Do About Delamination
A delaminating coating can’t be glued back down. The fix is to remove the loose material, find out why it failed, and then recoat. Ask your contractor:
- How will you remove the old coating? Full grinding is the standard.
- Will you test for moisture? A moisture test tells you whether you need a moisture-blocking primer.
- How will you check the concrete? Hollow spots in the slab itself should be repaired first.
Delamination FAQ
Can delamination be fixed?
Yes, but not by patching over it. The loose coating or weak concrete has to be ground off to a solid surface, the cause fixed, and a new coating applied. Small areas can sometimes be repaired; widespread peeling usually means redoing the whole floor.
What causes concrete to delaminate?
Concrete delamination usually comes from finishing the surface too early, which traps water and air just below a thin top layer. That layer later breaks loose under traffic. It’s a placement problem, not something a coating causes.
What is the difference between delamination and spalling in concrete?
Delamination is a layer separating from the material beneath it, often leaving a hollow sound before anything breaks off. Spalling is the surface chipping or flaking away, commonly from freeze-thaw cycles and deicing salts. Both need repair before coating.
Is delamination a problem?
Yes. A delaminating coating no longer protects the concrete, and the loose areas tend to grow. It also points to a prep or moisture issue that needs fixing before you recoat.