Painting Concrete Carpark and Common Area Floors in Strata

Carpark and common area floors are the most-used surfaces in most Melbourne strata buildings and the ones least often planned for. They also fail faster and more visibly than almost anything else when the work is scoped badly, because a floor coating has to survive vehicle traffic, tyre scuffing, water, and whatever comes off the cars.

Why floors fail, and it is almost never the paint

The overwhelming cause of floor coating failure is moisture in the slab, not a poor coating choice.

Concrete holds and transmits water. In a basement carpark, moisture moves up through the slab from the ground beneath, and where there is no effective vapour barrier under it, that movement is constant. A coating applied over a slab pushing moisture upwards gets forced off from underneath. It shows as blistering, bubbling, and sheets of coating lifting cleanly away with the underside still glossy.

This is why moisture testing is the first item in any honest scope. It is a simple test, it costs very little relative to the job, and it determines which coatings are even viable. A quote that does not mention moisture testing on a basement slab is guessing.

Preparation is mechanical, not chemical

Concrete has to be opened up before it will accept a coating. New concrete carries laitance, a weak surface layer, and older concrete carries embedded oil, rubber and sealer residue.

The standard approach is mechanical: diamond grinding or shot blasting to remove contamination and create a consistent surface profile. Acid etching is sometimes offered as a cheaper alternative and it is generally a false economy indoors, because it is hard to neutralise fully and it does not deal with oil at all.

Oil spots deserve specific attention. In a carpark they are everywhere, concentrated under the engine bay of every bay that has held an older car. Oil that has soaked into the slab has to be drawn out or cut out, not painted over.

Cracks and joints need treating on their own terms. Static cracks can be filled and coated over. Moving joints have to stay moving, and coating straight across them just relocates the crack into your new floor.

Choosing a system for the traffic

Not all floor coatings suit vehicles.

The failure mode specific to carparks is hot tyre pickup: a warm tyre sits on the coating, bonds to it, and lifts it when the car pulls out. Thin or poorly bonded coatings do this readily, which is why a system rated for vehicular traffic matters more than the colour or the brand.

Epoxy systems are the common choice for durability under vehicles, often with a topcoat for ultraviolet stability where daylight reaches the deck. Polyurethane topcoats handle sunlight and abrasion better. Where moisture is a known issue, moisture-tolerant primers or vapour-barrier systems exist and are worth the extra rather than gambling.

Slip resistance is a genuine safety and liability consideration, not an upgrade. Ramps, entries where cars bring rain in, and pedestrian routes through the carpark all need an appropriate finish, and a smooth glossy floor in those areas is a hazard.

Line marking, signage and compliance

While the floor is being done, everything painted on it is in scope: bay numbering, directional arrows, pedestrian walkways, hatching at fire services, visitor and accessible bay markings, and height or speed signage.

This is worth getting right because bay numbering ties directly to lot entitlements and title. Repainting a carpark and renumbering bays inconsistently with the plan of subdivision creates disputes that long outlive the coating. Photograph and record the existing layout before anything is ground off.

Staging around residents

A carpark cannot be closed for a week in an occupied building, so the program matters as much as the specification.

Most jobs are staged in sections, with a portion of bays closed at a time and residents relocated temporarily. That needs coordinating well in advance, and it needs a realistic allowance for cure time before vehicles return, which is longer than foot traffic cure time.

Ventilation is a real constraint in a basement. Coating systems have odour and vapour, and in an enclosed carpark under apartments that reaches the lobbies and lift shafts. Mechanical ventilation, timing, and choosing lower-odour systems where possible all belong in the scope, along with clear notice to residents.

Scoping it so quotes compare

The same principle applies here as to a facade repaint. Define the scope before going to market: moisture test results, the preparation method, the coating system and its traffic rating, slip resistance requirements, the line marking schedule, and the staging plan. Then the quotes are pricing the same job.

Where the extent of oil contamination or crack repair cannot be known until grinding starts, agree a schedule of rates up front rather than negotiating variations mid-job under pressure.

Treat it as a capital works item and program it alongside your other cyclical work, in the same way you would plan facade repaints and remedial preparation, rather than reacting once the floor is already failing.

If your owners corporation is considering a carpark or common area floor coating across Melbourne, Docklands, Southbank, Richmond, Carlton, Brunswick, Footscray or Box Hill, get in touch and we will help you scope it properly.