Concrete spalling is when pieces of the concrete surface crack, flake or pop off, most often because the steel rebar inside is corroding. Rust takes up several times the volume of the original steel, so it breaks the concrete apart from the inside. On commercial buildings it shows up on balcony slabs, parking decks, columns and facades, and it is often a sign of a deeper problem. Coastal Reconstruction Group, a Florida licensed general contractor, repairs spalling on commercial and condominium buildings with licensed engineers setting the repair plan: unsound concrete is removed, the steel is treated and the area is protected from water.
What is concrete spalling?
Concrete spalling is the loss of surface concrete in chips, flakes or chunks, often exposing the stone aggregate or the reinforcing steel underneath. A "spall" is the broken piece, or the hole it leaves behind.
Three related terms come up in inspection reports, and the difference matters:
- Spalling: concrete has already broken away, leaving a visible depression.
- Delamination: a layer of concrete has separated below the surface but has not fallen off yet. It sounds hollow when tapped and often becomes a spall later.
- Scaling or pitting: shallow surface wear from weathering or poor finishing that does not reach the steel.
Spalling and delamination near reinforcement usually point to corrosion. Shallow scaling with no exposed steel is usually cosmetic.
What causes concrete spalling in commercial buildings?
The most common cause in reinforced concrete is rusting steel. The Federal Highway Administration explains that the corrosion products of steel occupy several times the volume of solid steel, which cracks and spalls the concrete cover once enough corrosion has built up. The usual triggers on commercial property:
- Salt air and salt water. FHWA research notes this kind of deterioration was first observed in marine structures and that even a small amount of chloride reaching the steel can start corrosion. Buildings along the Florida, Georgia, Carolina and Texas coasts are exposed to airborne salt every day.
- Thin concrete cover. Rebar placed close to the surface gives water and salt a short path to the steel. Balcony edges and slab undersides are frequent trouble spots.
- Water getting in. Worn balcony coatings, cracked sealant joints, ponding on decks and leaking railing post pockets keep concrete wet and feed corrosion.
- Age. Older concrete has had more years of exposure to moisture and salt, so spalling is more common on aging buildings.
- Other causes. Fire, vehicle impact and poor original finishing or curing can also spall concrete.
Where does spalling show up on commercial properties?
CRG's structural repair work covers concrete, masonry, steel and wood frame systems, and on commercial buildings spalling tends to cluster in the same places:
- Balcony slabs and railing posts on condominiums, apartments and hotels, where water collects at slab edges and post pockets.
- Parking garage decks, ramps and ceilings, where vehicles track in water and traffic coatings wear through.
- Columns and beams, especially at ground level near pools, drives and irrigation.
- Facades, eyebrows and slab edges, where loose pieces can fall onto walkways below.
- Pool decks, breezeways and exterior stairs that stay wet and carry heavy foot traffic.
Is concrete spalling a structural problem?
Sometimes. Spalling becomes a structural concern when corroding reinforcement sits inside a load-carrying element such as a column, beam, slab or balcony, and only a licensed engineer can make that call.
Florida law draws the same line. Under section 553.899 of the Florida Statutes, surface imperfections such as cracks, signs of leakage or peeling finishes do not count as "substantial structural deterioration" unless the licensed engineer or architect performing the inspection decides they are a sign of it.
Signs that call for an engineer rather than a cosmetic patch:
- Exposed or visibly rusted rebar
- Rust stains bleeding from cracks
- Cracks that follow the line of the reinforcement
- Areas that sound hollow when tapped
- Spalling on the underside of balconies, slabs or garage decks above walkways or parking
Overhead spalling is also a safety issue. Loose concrete above an entrance, walkway or drive should be cordoned off until it is removed or made safe.
How do Florida milestone inspections treat spalling?
For condominium and cooperative buildings three habitable stories or taller, Florida requires a milestone inspection by December 31 of the year the building reaches 30 years of age, then every 10 years. The local enforcement agency can move the first inspection to 25 years based on local conditions such as proximity to salt water.
Phase one is a visual examination by a licensed architect or engineer. If phase one identifies substantial structural deterioration, a phase two inspection follows, which may include destructive or nondestructive testing. Spalling found during these inspections often becomes the repair scope a board has to fund, and our post on Florida milestone inspections and board budgeting covers how to plan for it.
How is commercial concrete spalling repaired?
Commercial spalling repair follows an engineer's design, not a patch kit. On Coastal Reconstruction Group's structural repair projects, licensed engineers assess the damage and set the repair plan, field crews build to that specification, and the finished work gets independent inspection sign-off. Typical steps:
- Assessment and mapping. The engineer surveys the structure, sounds the concrete for delamination and marks repair areas on drawings.
- Shoring and protection. Temporary supports go in where the engineer requires them, and walkways and parking below are protected.
- Concrete removal. Unsound concrete is removed around each damaged area until sound concrete and the full corroded length of steel are exposed.
- Steel treatment. Rust is cleaned from the reinforcement. Steel that has lost too much section is supplemented or replaced as the engineer directs.
- Rebuilding the section. The area is restored with repair mortar or formed and poured concrete, then cured.
- Protection. Coatings, traffic membranes, sealants and drainage fixes keep water away from the repaired concrete.
- Inspection and closeout. The engineer inspects the work and the owner receives documentation of what was repaired.
What affects the cost and schedule of spalling repair?
Spalling projects are hard to price from the surface, because the true extent of damage is often only known once unsound concrete comes out. The main drivers:
- Total area and depth of repairs, and how much steel needs replacing
- Access, such as scaffolding, swing stages or lifts for balconies and facades
- Shoring the engineer requires
- Waterproofing and coatings added after the structural work
- Whether residents, guests or tenants stay in the building during the work
CRG's structural repair page puts most structural repairs at 2 to 10 weeks after engineering sign-off. On occupied buildings, CRG phases the work floor by floor or building by building and assigns a tenant liaison to handle resident communication and unit access, as described on its multi-family construction page.
How do you keep spalling from coming back?
Keep water and salt away from the steel. After structural repairs, CRG's roof and envelope services address the water entry points that started the damage: balcony and deck coatings, sealant joints, railing post pockets, drainage and slope. Regular visual checks of balconies, garages and facades help catch new delamination while repairs are still small. If balconies are part of the problem, our article on choosing balcony repair contractors lists the credentials to ask for.
Next steps
If an inspection report or a walk of the property has turned up spalling, start with an engineer's assessment and a contractor who can carry the repair from shoring through waterproofing. Coastal Reconstruction Group is headquartered in Longwood, Florida, is licensed in 32+ states and works across Florida, Georgia, Alabama, the Carolinas and Texas. Contact CRG to talk through your building's spalling repair and restoration scope.
Frequently asked questions
Is a surface patch enough for spalled concrete?
Usually not when steel is involved. A patch placed over corroding rebar traps the problem, and the rust keeps expanding until the patch cracks or falls off. Repairs last when unsound concrete is removed, the steel is cleaned or replaced, and the source of water is fixed. Shallow scaling with no exposed steel can sometimes be patched.
Who should inspect spalling on a commercial building?
A licensed structural engineer, or for Florida condominium buildings, the licensed engineer or architect performing the milestone inspection. They decide whether the spalling is cosmetic or structural and design the repair. The contractor then builds the repair to that design, and the engineer inspects the finished work.
Can spalling repair be done while the building is occupied?
Often, yes. The work is phased so residents, guests or tenants keep using the building, with protected walkways below active areas and scheduled access to balconies or units. Coastal Reconstruction Group delivers occupied renovations and repairs across the Southeast and assigns a tenant liaison on multi-family work.
Does insurance cover concrete spalling repair?
That decision belongs to the insurance carrier and depends on the policy and the cause of the damage. Spalling from a sudden event may be treated differently than long-term deterioration. When a claim is involved, CRG prepares estimates in Xactimate and works with carriers, adjusters and TPAs, but it cannot promise a coverage outcome.
