Small Bumps on a Concrete Floor: Could They Be Blisters?
Small, shallow bumps on a concrete floor may be blisters: pockets beneath a thin surface layer. Record their location and ask the contractor to examine them before choosing a repair. A raised spot alone does not establish the cause, the extent of the problem, or whether the entire floor needs work.
What the term blister means
The National Ready Mixed Concrete Association describes blisters as low, hollow bumps associated with trapped air or bleed water beneath a prematurely closed concrete surface. They can develop during finishing, yet small ones may escape notice until traffic breaks the thin covering. Larger areas of this kind of separation are called delamination.
That explanation is a starting point for an inspection, not a diagnosis from a photograph. Tell the contractor whether the bump is in exposed concrete or in an applied floor covering. Ask them to identify which material is affected before discussing products or repair methods.
Make a useful record without opening the bumps
Take one photograph that shows the room and another that shows the individual spot, with a ruler nearby for scale. Mark each location on a simple sketch. Note when you first saw it, whether it was already broken, and whether similar spots appear elsewhere. Do not chip open intact areas just to improve the photograph.
For a Middle Tennessee shop or commercial floor, include a short description of normal use: walking, carts, vehicle movement, or storage. Share the placement date and any finishing or coating records you have. If a spot is disrupting operations, explain the immediate access concern separately from the request for a permanent repair.
Ask for repair boundaries, not just a patch price
NRMCA cautions that blisters are not easily repaired after the concrete hardens. Before approving work, ask how the contractor will establish the affected area and what finding would change the proposed scope. Request a clear distinction between confirmed damage and areas still requiring assessment.
Ask what the finished repair should look like, what use restrictions apply, and who will authorize reopening. Keep those answers with the proposal so expectations are recorded before work begins. Milliken Corporation lists floor slabs and concrete repairs among its services; provide the floor location, photographs, and intended use when requesting a review.
Frequently asked questions
Does noticing a blister later mean it formed later?
Not necessarily. A small blister may be difficult to see initially and become noticeable only when its covering breaks. Record the discovery date without assuming it is the formation date.
Should I request replacement of the whole floor?
Start by requesting an assessment of the affected area. Ask for the evidence behind any recommendation, whether it involves localized work or a broader repair, rather than selecting the scope from the appearance of one spot.