Resurface or replace: how to tell

Resurfacing is a thin layer of polymer-modified cement or an overlay bonded to the existing slab. It fixes what is on the surface and depends entirely on the concrete under it being solid, level and stable. A driveway is a candidate when the problems are cosmetic.

The test is whether the slab still sits flat and still. If a straightedge across a joint shows no step, and cracks have stayed the same width through a few winters, the base is doing its job.

• Flaking or scaling from deicers or a weak original finish
• Shallow spalling and pitting less than about a quarter inch deep
• Hairline cracks that have not widened or moved from year to year
• Stains, tire marks and a dull or uneven finish
• Panels that are still level with each other at every joint

The base is the compacted stone and soil the slab rests on. When water gets under a driveway, the base washes out or softens, and the concrete above it loses support. The slab then cracks under its own weight and the weight of the cars on it. Once that happens, the surface is a symptom, and treating the symptom leaves the cause in place.

• A panel that has sunk below its neighbor at a joint
• A panel that has heaved up, usually at a tree root or a wet spot
• Cracks wider than a quarter inch, or cracks with one side higher than the other
• Cracks that spread in a map pattern across a whole panel
• Water that pools on the slab instead of running off
• Movement you can feel when a car rolls across a joint

A resurfaced driveway is only as stable as the slab it is bonded to, and the slab is only as stable as the base. If a panel settled because water washed out the stone under it, an overlay makes the surface look new for a season. The water is still there, the void is still there, and the next freeze or the next loaded truck cracks the overlay along the same line as the old crack. The homeowner has now paid for the surface twice and still needs the replacement.

The same logic applies to slab lifting. Lifting a sunken panel works when the cause of the sinking has been fixed. Lifting it over an active drainage problem buys time and little else. Replacement fixes the base first: the old slab comes out, the soft material is excavated, new stone is placed and compacted, and the drainage that caused the problem is corrected before a form is set.

Resurfacing makes sense for a structurally sound slab with a tired surface, or where the goal is a decorative finish over a plain one. Replacement makes sense when panels have moved, when cracks go through the full depth, when the drive is thinner than it should be for the vehicles on it, or when the layout needs to change anyway, such as widening or adding a turnaround. Partial replacement, cutting out the failed panels and pouring them new, sits between the two and works when the failure is limited to a few sections and the rest of the base is sound.

Age helps with the decision too. A slab poured decades ago with no reinforcement and a thin base often has more panels on the way out than the ones already showing damage, and replacing it once beats chasing it panel by panel.

Morgan's tears out and replaces residential driveways, patios, sidewalks and floors, including the demolition, haul-off and base rebuild. If you are weighing resurfacing against replacement, ask us to look at it. Joe walks the slab, checks the joints for movement, looks at how water leaves the property and tells you plainly which one the concrete needs. If the slab is sound and a surface treatment would serve you, he says so. Replacement details are on the tear-out and replacement page linked below.