Concrete pitting

Pitting is small-scale loss of the surface, leaving shallow depressions scattered across an area rather than the clean cones of a popout or the sheet loss of scaling.

It is one of the conditions most likely to be met with a sealer recommendation, and sealing is sometimes right and sometimes treats the wrong thing. What separates those cases is whether the surface is still losing material.

What it is

The surface loses small amounts of paste and fine material in localised spots. The pits are typically shallow, irregular in outline, and distributed rather than concentrated — which is what distinguishes the appearance from spalling or delamination.

In exterior slabs it very commonly concentrates where de-icing salt collects and where water sits: the parking area of a driveway, the base of steps, the apron area where a car sheds melting snow after a drive.

Indoors it is more often associated with a weak surface layer — a floor that was overworked or cured poorly and has been abraded by traffic.

What seeing this cannot establish

• Pitting depth is not visible from a photograph, and depth is what separates a cosmetic surface texture from progressive loss.
• Whether the surface is still deteriorating cannot be established from a single look. That needs a comparison over time.
• Pitting, early scaling and heavy abrasion overlap in appearance and have different associations, which is why the pattern and location matter more than the texture itself.

What this can be associated with

Candidate explanations, not findings. Nobody can establish which applies to your concrete without seeing it.

• De-icing salt exposure combined with freeze-thaw cycling, which can be associated with surface loss concentrated where salt collects
• A weak surface layer from overworking during finishing, or from curing that ended early
• Water sitting on the surface rather than draining, which extends the time salt and freezing act
• Abrasion from traffic, shovels, or grit on a surface that was already weak
• Chemical exposure — fertiliser, some cleaning products — on a surface without protection

What you can safely check yourself

• Rub a hand firmly across the pitted area. If you pick up grit and fines, the surface is still coming away, and that changes the answer.
• Note where the pitting is worst. Concentration where salt collects or water sits supports a de-icing and freeze-thaw association.
• Photograph a representative area with raking light — low sun or a torch held near the surface shows depth far better than flat light.
• Feel the depth with a fingertip. Barely perceptible texture and pits you can feel a fingernail drop into are different conditions.
• Chalk an outline around the worst area and photograph, so extent can be compared later.
• Note whether salt is used and whether the area drains or ponds.

When this is frequently cosmetic

• Shallow surface texture that no longer sheds material, on an exterior slab that drains
• Light pitting on a utility or garage slab where appearance is the only consequence

When professional evaluation matters more

• The surface is still shedding grit and fines when rubbed
• Pits are deep enough to expose coarse aggregate
• The pitted area is extending between dated observations
• The slab is a pool deck, barefoot area or interior floor where surface quality matters
• Pitting coincides with scaling or spalling, suggesting a broader surface durability problem

When replacement enters the conversation

• Surface loss has progressed to expose aggregate over a large proportion of the slab
• The slab is thin and continued surface loss is reducing effective thickness
• Resurfacing has already been done once and the underlying surface is still failing

Evidence worth having before you ask for estimates

Every item here is something you can produce without tools or risk, and every one of them makes an estimate more accurate.

• A raking-light photograph showing depth
• A note of whether the surface sheds material when rubbed
• A chalked extent outline, photographed and dated
• Whether salt is used, and where it collects
• Drainage observations after rain

Questions to ask whoever comes out

• Is the surface still deteriorating, or has it stabilised? How can you tell?
• If you recommend sealing, what is the sealer doing here — protecting sound concrete or covering loss?
• Would resurfacing be a better use of the money than repeated sealing?
• Does the drainage need addressing for anything to last?
• What preparation does the surface need before a sealer or overlay will bond?

Where estimates for this commonly differ in scope

These are the places two prices for apparently the same work stop being comparable.

• Sealing a stable surface and resurfacing a failing one are different products for different situations, and both are commonly offered for pitting without distinguishing which case applies.
• Preparation is where overlay estimates differ most and is described least.
• Some estimates include drainage correction and most do not, even where ponding is part of the story.

Who tends to do this work

• A concrete repair specialist
• A decorative or specialty concrete finisher
• A drainage contractor or landscaper who does grading

ConcreteOwner does not inspect, certify or approve contractors. This describes which trade usually holds this work, not a recommendation of anybody in particular.