Why is my stamped patio flaking in Orleans?

Surface flaking on stamped concrete, called scaling, has a few possible sources worth having a contractor look at: the condition of the concrete at the time it was placed and finished, how it was cured, and what it has been exposed to since. The National Research Council's Canadian Building Digest 116 notes that surface scaling occurs mainly on horizontal surfaces and is most severe where de-icing salts have been used alongside freeze-thaw cycling, and that freezing concrete in the plastic state, before it has hardened, can cause permanent damage even from a single cycle.

A few things are worth checking on your patio specifically. The 2024 Ontario Building Code sets a minimum compressive strength of 32 MPa for exterior flatwork, and the appendix to the Code notes that adding water to concrete on site can reduce strength and increase porosity and the tendency to shrink and crack. Canadian Building Digest 116 also notes that over-vibration and excessive trowelling can affect entrained air adversely, which matters for frost resistance. None of this is a diagnosis; a contractor who can look at the surface in person can say what happened.

On the product side, the Ready Mixed Concrete Association of Ontario advises, as industry guidance, to avoid de-icing chemicals on concrete, especially in the first winter, and to use sand instead. The same industry guidance names ammonium sulfate, ammonium nitrate, calcium chloride and magnesium chloride as de-icers never to use. If any of those have been used on or near the patio, that is worth mentioning to the contractor.

Since March 1, 2026 the City of Ottawa has required a hardscaping contractor licence for businesses that install or alter hard landscaping features such as patios. The Licensing By-law also excludes "minor repairs or minor alterations", which it does not define, so ask the City whether your job counts. The licence requires the contractor to carry commercial general liability insurance of not less than $2,000,000 per occurrence and automobile liability insurance of not less than $2,000,000, to provide a written contract, and to give you a copy of the City's Landscaping Education Guide. The City publishes a list of licensed hardscaping contractors; ask to see the licence and check the list yourself. We found no provincial licence for concrete contractors, and the Cement (Concrete) Finisher trade through Skilled Trades Ontario is non-compulsory.

We found too few published prices for crack repair, resurfacing or partial replacement to give a reliable range, so get that itemized in any quote. Ask the contractor to put the proposed repair method, the concrete specification if new material is being placed, and what surface preparation is included, all in writing.

Before you agree to any repair scope, ask the contractor to explain in writing exactly what they believe caused the flaking and how the proposed repair addresses that cause.