A sealed patio slab is far more resistant to water, staining, and freeze damage than bare concrete, but it still needs regular maintenance. Exposure to UV, rain, algae, and foot traffic will eventually break down the sealer. Poor maintenance leads to fading, flaking, and surface grime. Whether your slab is sealed with acrylic, silane, or polyurethane, this guide explains how to maintain it properly to extend performance and appearance.
Avoid acidic patio cleaners or bleach that can damage the sealer. Use a pH-neutral detergent and a soft-bristle brush or pressure washer set to a low bar. Focus on removing dirt, moss, algae, and any greasy residue from barbecues or furniture. Rinse thoroughly. Let the surface dry completely before applying any further treatment. For patterned or coloured slabs, test the cleaner on a small area first to avoid colour leaching.
After cleaning, check the slab for signs of worn or patchy sealer. Look for darkened areas when wet, surface chalking, or dull zones where the film has broken down. If water soaks into the surface instead of beading, it’s time to reseal. Pay close attention to south-facing areas, edges, or zones under pots and furniture where wear is uneven. Photograph or mark high-wear areas for touch-up.
Use the same product type that was originally applied, acrylic with acrylic, silane with silane, etc. Mixing systems can cause whitening or adhesion failure. If unsure, test compatibility in a discreet corner. Apply the new coat in dry weather, above 10°C, and allow full cure before rain or traffic. Two light coats are usually better than one thick one. Avoid application in direct sunlight or onto hot slabs.
Drainage is essential for sealed outdoor slabs. Remove leaves, weeds, and mulch that trap water against the surface. Brush back soil or gravel that sits over expansion joints or slab edges. Where slabs meet turf or planting beds, keep at least 10 mm clear to avoid saturation. Excess moisture leads to moss growth and early breakdown of water-based sealers.
High-pressure cleaning can strip or scar the sealer. Use a fan tip and keep the lance at least 200 mm off the surface. Do not use solvent-based degreasers, brick acid, or patio bleach, they strip protective coatings and damage the concrete underneath. For stubborn marks like tyre scuffs or barbecue spills, use a specialist concrete cleaner or citrus-based degreaser that is safe for sealed surfaces.
Even high-performance sealers wear faster in traffic paths, under tables, or near hose reels and gates. Once a year, inspect these areas and apply a spot recoat if needed. Lightly abrade with a sanding screen to help the new coat bond. Recoating small areas extends system life without needing a full reapplication every time. Always clean the surface first and allow it to dry before touch-up.
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