How to Inspect a Concrete Surface Before Resurfacing

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Don’t Resurface Until You’ve Checked This First

Resurfacing a concrete floor, path, or driveway sounds simple — but skipping a proper surface inspection is the easiest way to waste time and materials. Not all slabs are ready to be overlaid. Some have deep cracks, movement, moisture issues, or surface delamination that will cause new layers to fail. This guide walks you through exactly how to inspect a concrete surface before resurfacing, so you know what repairs are needed and what’s safe to proceed with.

Why Surface Inspection Matters:

  • Identifies structural vs cosmetic problems
  • Reveals hidden moisture or contamination
  • Prevents overlay failures or delamination
  • Ensures the slab can bond with new materials

✔ Step-by-Step: How to Inspect a Concrete Surface Before Resurfacing

  1. 1

    Walk the Surface and Check for Visible Damage

    Begin with a slow, methodical walk across the slab. Look for cracks, spalling, scaling, heaving, or surface flaking. Note where damage is concentrated (corners, joints, edges) and how widespread it is. Use chalk or spray paint to mark areas that need deeper evaluation. Light cracking may be superficial, but wide, jagged, or offset cracks may signal movement or structural issues that must be resolved before resurfacing begins.

  2. 2

    Tap Test for Hollow or Delaminated Zones

    Use a metal tool or hammer to gently tap the surface in a grid pattern. A solid, dense slab will give off a sharp, tight sound. Hollow or delaminated areas will sound dull or hollow. These spots are at high risk of failure if coated or resurfaced — they need to be broken out and repaired before any new layer is added. Pay extra attention to corners, joints, or previously patched sections where delamination is more common.

  3. 3

    Test Surface Hardness and Profile

    Determine how hard and dense the surface is using a Mohs scratch test or a surface hardness tester. This helps identify areas that may polish or bond inconsistently. You should also assess the CSP (Concrete Surface Profile) — smoother slabs may need mechanical roughening before resurfacing. If the surface is powdery or dusty, it likely has weak laitance that will need grinding off for proper bonding. You’re aiming for a clean, roughened surface that can hold onto new material.

  4. 4

    Check for Moisture and Vapor Emission

    Excess moisture ruins most resurfacing jobs. Use a calcium chloride test or moisture meter to measure MVER (moisture vapor emission rate). Even slabs that appear dry can have high internal moisture moving toward the surface. If MVER is over 3–5 lbs/1000 sq ft/24 hrs (depending on product used), it will compromise bonding, especially for epoxy, polish, or microcement. In high-moisture areas, vapor barriers or breathable overlays may be needed instead.

  5. 5

    Identify Contaminants and Old Coatings

    Residues like oil, paint, glue, adhesives, and curing compounds interfere with overlay bonding. Check for dark stains, sticky zones, or glossy patches that indicate contamination. A simple water drop test (watch if water beads or soaks in) helps spot sealer or oil presence. Contaminated areas must be degreased, scarified, or ground clean before resurfacing. Any shortcut here almost always leads to blistering, bubbling, or peeling overlays later on.

  6. 6

    Look for Movement Joints or Structural Concerns

    Identify all expansion joints, control joints, and cracks that show signs of movement. Resurfacing over these without proper joint honoring can lead to telegraphing or tearing of the overlay. If structural cracks are active (edges don’t align, or new cracks are forming), you may need structural repair before cosmetic resurfacing is safe. Use a crack gauge or visual monitoring over time if needed to confirm whether movement is ongoing or stable.

  7. 7

    Summarise and Plan Surface Preparation

    Based on your inspection, create a prep plan: which areas need grinding, patching, or moisture protection? Which sections are sound enough for overlay? A proper inspection isn’t just about identifying problems — it’s about mapping the prep process so no surprises happen once work begins. Include surface profile goals, equipment needed, and repair methods for all flagged defects. The better the inspection, the smoother the resurfacing.

What happens if you resurface over a hollow or cracked area?
Any hollow or cracked zone that isn't repaired can lead to failure — the overlay may delaminate, crack, or pop off. Always repair or remove damaged sections before applying new layers.
How do you know if the concrete is too wet to resurface?
Use a moisture meter or calcium chloride test. If MVER readings are too high, most coatings and overlays will fail. Slabs need to dry out or be treated with vapor-blocking primers.
Can you resurface over old sealers or paint?
No — old sealers, adhesives, or paints must be removed before resurfacing. They prevent proper bond and lead to bubbling or delamination. Always grind or scarify to bare concrete first.

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