Concrete Problem Guide
Concrete Spalling: What It Is, What Causes It, What Actually Helps
By Mike Romer, Owner · OKGN Concrete Sealing · Updated July 2026
Quick Answer
Concrete spalling is the surface of the slab breaking away in chunks or flakes, often exposing the aggregate (stones) underneath. In the Okanagan it's almost always freeze-thaw damage: water gets into the concrete, freezes, expands about 9%, and blasts the surface apart — with winter road salt accelerating it. Sealing prevents spalling by keeping water out of the slab, and it can stop early, minor spalling from spreading. But sealing cannot rebuild concrete that's already broken away — deep or widespread spalling needs a repair or resurfacing contractor, and we'll tell you which side of that line you're on.
What You're Seeing
What Spalling Is — and What's Happening Underneath
Spalling is when the top layer of a concrete surface breaks off — anything from small coin-sized pops to whole patches flaking away and exposing the rough aggregate underneath. It usually starts at edges, joints and high-traffic spots, and it gets worse every winter once it begins.
What's happening underneath: concrete is porous, and water that soaks in expands when it freezes. Each freeze-thaw cycle wedges internal fractures a little wider until the surface layer loses its bond and breaks free. De-icing salt makes it worse two ways — it lets water refreeze more times per winter, and it chemically attacks the cement paste.
Root Causes
What Causes Spalling in the Okanagan
Freeze-thaw cycling
The Okanagan's winter habit of hovering around 0°C — Kelowna alone sees roughly 69 freeze-thaw cycles and 150 frost days a year — is the primary driver. Water in the pores freezes, expands, and fractures the surface from within.
Road salt & de-icers
Salt lowers the freezing point, so trapped water cycles through more freezes per winter, and the salts themselves degrade the cement paste and corrode any rebar near the surface.
A weak finished surface
Overworked, overwatered or poorly cured concrete has a weaker top layer to begin with. It spalls sooner — sometimes within a few winters of a new pour.
Freeze-thaw is the engine behind most Okanagan concrete damage — see the government climate data for your city in our city-by-city freeze-thaw breakdown.
The Honest Verdict
Sealing prevents spalling — it can't rebuild what's gone
This is the damage penetrating sealing exists to prevent: keep water out of the slab and freeze-thaw has nothing to work with. If your concrete is sound, or spalling is just starting in a few small spots, sealing now is exactly the right move — it stops the water intrusion that drives the damage deeper. But we'll be straight with you: sealer is not a patching product. If the surface is already broken away across large areas, or the damage runs deep enough to expose aggregate everywhere, you need a concrete repair or resurfacing contractor first — sealing comes after, to protect the fix. On a free assessment we'll tell you plainly which situation you have.
Prevention
How to Keep Spalling From Starting (or Spreading)
Seal the concrete before winter — a penetrating sealer fills the pores so water can't get in and freeze. Minimize de-icing salt (use sand for traction where you can), keep drainage moving water off the slab, and don't let snowmelt pool against edges and joints.
FAQ
Concrete Spalling: Common Questions
01Can you fix spalled concrete by sealing it?
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Sealing stops spalling from getting worse — it can't undo it. A penetrating sealer keeps water out of the slab, which removes the freeze-thaw force driving the damage. If spalling is minor and the slab is otherwise sound, sealing now is the right call. If chunks are already missing across large areas, that's repair or resurfacing territory first; sealing then protects the repaired surface. We don't do the repair work ourselves, and we'll tell you honestly if that's what you need.
02Why is my driveway spalling after only a few years?
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Usually one of three things: the surface was weakened during finishing or curing (common on rushed pours), de-icing salt was used heavily in the first winters, or the concrete was never sealed and the Okanagan's freeze-thaw cycles — roughly 69 a year in Kelowna — got to work early. New concrete is not immune; it should be sealed once it's fully cured.
03Will spalling spread if I ignore it?
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Yes. Spalling is progressive — every broken spot gives water a bigger, deeper way into the slab, and every winter's freeze-thaw cycles pry the damage wider. A few small pops this year can become whole flaking patches in two or three winters. The earlier the water is shut out, the more of the slab you keep.
Not Sure How Bad Your Spalling Is?
We'll look at it in person and tell you straight — whether sealing is the right fix, or whether you need a repair contractor first. Free, no-obligation, anywhere in the Okanagan.