Sandstone cleaning and sealing on Collaroy Plateau

Most Collaroy Plateau sandstone is part of the landscaping. Blocks falling toward the coast are cut into terraces, held by sandstone retaining walls and linked by stone stairs, with a paved terrace or pool area placed to take in the view. On the sunny, exposed side, stone is pale and carries lichen. Under trees or in the lee of the house, it is darker with mould and algae. Paving near native gardens picks up tannin from leaves and flowers. Our technicians map these zones and trial a cleaner on each before starting, so the treatment matches the problem instead of using one strength everywhere on the block.

Lichen, mould and algae get a stone-compatible biocide and a dwell long enough for the growth to die back at the root. Soft brushes and a gentle rinse remove the dead growth, and a turbo tip never comes near the sandstone. Tannin marks get a targeted cleaner, or a poultice for deeper staining. On terraced gardens, containment is set at the base of each level so wash water is recovered before it can reach the terrace below, the street or the drains leading downhill. Leaves are cleared before stone gets wet, nearby plants are protected, and the recovered water leaves with us for appropriate disposal.

Paving, steps, pool coping and wall caps on the Plateau usually suit a breathable penetrating sealer, which slows lichen, algae and tannin and lets leaf litter brush off more easily. Retaining walls in front of damp soil go without, so moisture can escape. Because the Plateau is exposed, sealing is saved for a windless, dry day; wind dries the product unevenly and can blow grit onto the wet surface. Small samples of natural and enhancing finishes let you choose the look before the main application. We keep a record of product and date. Once a year, sprinkle a little water on shaded steps and the most exposed terraces; if it soaks straight in, call us.