Commercial space preparation is where most paint jobs are won or lost. The paint itself might account for 20% of the outcome; the condition of the surface underneath accounts for the rest. A coat applied over dirty, damaged or poorly primed surfaces won't hold, no matter what the tin says on the label. Here's how to prepare a commercial space so the paint lasts and the finish looks professional from day one.
Start with a proper condition assessment
Before any tape goes up or drop sheet hits the floor, Apex Painting conducts a thorough inspection of every surface. Walls in commercial spaces take more punishment than residential ones. Trolley impacts, bracket fixings, tape residue from signage, grease migration in kitchens, and moisture from poorly sealed windows all leave marks that preparation must address.
Walk every wall, ceiling and skirting in good light. Note peeling paint, chalking, efflorescence on concrete or masonry, rust staining near metal fixtures, and any areas where moisture has caused the substrate to swell. Each of these problems has a different fix, and conflating them is how contractors create expensive callbacks.
Cracks deserve particular attention. Hairline cracks in plaster are cosmetic and fill easily with a flexible filler. Cracks that run diagonally from window corners, or that appear over doors, can indicate structural movement and need an engineer's sign-off before they're painted over. Covering a structural crack with paint doesn't fix it. It hides it until the crack reappears through the fresh coat, usually within six months.
Surface cleaning: the step most teams rush
Commercial surfaces accumulate grime that's invisible from a metre away but enough to prevent adhesion. Sugar soap washing is the minimum for interior walls. For heavily soiled areas, such as a commercial kitchen or a workshop wall, a degreaser applied with a stiff brush and thoroughly rinsed is non-negotiable.
Exterior surfaces need pressure washing, typically at 1,500 to 3,000 psi depending on the substrate. Brick and concrete can handle the higher end. Render and older painted timber need a gentler approach, because high pressure on a degraded surface strips more than dirt. It strips the paint you were hoping to paint over.
Allow adequate drying time after washing. On a dry Melbourne day in summer, rendered walls typically need 24 hours. In winter, or on south-facing elevations, 48 hours is more realistic. Painting onto a damp substrate is one of the most common causes of early paint failure, and it's entirely avoidable with a moisture meter and a bit of patience.
Repairs and filling before primer goes on
Every hole, dent and crack needs to be filled and sanded flush before priming begins. In commercial spaces this step is more involved than in residential settings, because the walls have often been through multiple tenancy fit-outs, each leaving behind its own damage.
Use the right filler for the substrate. Lightweight fillers work well for small holes in plasterboard. Deeper voids in masonry need a cementitious filler that won't shrink back as it cures. Flexible, paintable caulk handles the joins between walls and skirtings, around architraves, and at ceiling lines. These joints move with the building, and a rigid filler in a flexible joint cracks within a season.
Sand every repair flush once it's fully cured, not just surface-dry. Running a hand over the wall tells you more than your eyes will. Any ridge or depression shows through a fresh coat of paint in raking light, and commercial spaces often have strong directional lighting that makes surface imperfections visible from across the room.
Masking, protection and staging the space
Commercial painting preparation includes protecting everything that isn't being painted. Floors, furniture, equipment, light fittings, switchplates, and any glass all need covering. In an occupied or partially occupied space, this step also means agreeing on which zones are sealed off and for how long. If you're managing an active business during the repaint, the staging plan is as important as the paint itself.
Apex Painting uses heavy-duty floor protection film on hard floors rather than standard drop sheets, which shift underfoot and create a trip hazard. Fixed furniture gets wrapped in plastic sheeting secured with masking tape. Light fittings get bagged. Fine mist from sprayed coatings travels further than most people expect, so any equipment that's sensitive to dust or overspray needs to be moved out or covered completely.
For guidance on managing the operational side of a commercial repaint, the article on how to minimise business disruption during a commercial repaint covers staging, sequencing and communication with staff in detail.
Priming: not optional, not interchangeable
Primer is the step that ties surface preparation to the finish coat. The right primer depends on the substrate and the condition of any existing paint.
New plasterboard needs a PVA sealer before any water-based topcoat goes on. Unprimed plasterboard absorbs paint unevenly, leaving a patchy finish regardless of how many topcoats follow. Previously painted surfaces in good condition typically need a light sand and a coat of adhesion primer if the sheen is high. Glossy surfaces don't bond well to fresh paint without either sanding back or a dedicated bonding primer.
Bare masonry and concrete need a penetrating sealer or block-filler to close the pore structure before finish coats. Without it, the topcoat sits on the surface rather than bonding into it, and the first knock or scuff pulls the paint away cleanly. For commercial spaces with high traffic, painting concrete floors in commercial spaces follows the same logic: preparation and primer selection determine whether the coating survives real-world use or fails within weeks.
Dulux Professional publishes substrate-specific priming guides that are worth consulting when the surface condition is unusual or the existing coating type is unknown. Following the manufacturer's recommendations matters because a mismatched primer-topcoat combination can cause adhesion failures even on a perfectly prepared surface.
Ventilation and temperature during preparation and painting
Preparation work generates dust. Sanding generates a lot of it. Commercial spaces with HVAC systems need those systems turned off or isolated before sanding begins, otherwise the dust circulates through the building and settles on surfaces you've already cleaned. Seal return air vents with plastic sheeting before sanding starts.
Temperature and humidity matter more than most clients expect. Water-based paints applied below 10°C don't cure properly. They dry on the surface but remain soft underneath, and a surface that looks dry after four hours may still be easily damaged. Solvent-based coatings have their own temperature windows. In Melbourne, where winter can push temperatures into single digits overnight, scheduling interior work so fresh coats don't sit in cold, unheated spaces overnight is part of a proper job.
Relative humidity above 85% causes water-based paint to dry too slowly and can trap moisture under the film. Below 30%, paint dries too fast, leaving brush and roller marks that can't be worked out. Commercial painters who skip these checks end up with finishes that look fine on the day and fail within a year.
When to call Apex Painting
Preparation is skilled work. It's not glamorous, but it's where the quality of a commercial paint job is decided. A contractor who gives you a lower quote by skipping preparation steps isn't saving you money. The rework bill arrives later, and it's almost always larger than the saving.
Apex Painting handles commercial surface preparation across Melbourne for offices, retail tenancies, warehouses, hospitality venues and strata buildings. If you're planning a repaint and want a clear picture of what preparation your space needs and what it will cost, our commercial painting cost guide for Melbourne businesses breaks down how preparation, materials and labour interact to set the final price.
Get the preparation right and the paint does its job. It's that straightforward.