Sandstone cleaning and sealing in Duffys Forest

On Duffys Forest acreage, sandstone is usually grouped around the house: terraces off the living areas, steps down to a lawn or pool, retaining walls where the block was levelled, and sometimes natural outcrops left as garden features. Under the canopy, these surfaces stay cool and damp, and black mould and green algae build up on anything facing south. Leaves pile into corners and stain the stone brown as they break down, and stormwater can carry red soil onto paths and edging. Our technicians inspect each area, note which marks are surface growth and which are stains, and run trial cleans before recommending a full scope and timeline.

We spray mould and algae with a biocide that is safe on sandstone and leave it undisturbed, so they die at the root rather than simply being blasted off the top. After that, soft brushes and a low-pressure rinse remove the dead growth without eroding the stone. Tannin and iron marks get separate, trialled treatments, sometimes a poultice. Older dry-laid walls are cleaned with especially light pressure so soil and small stones are not washed out. Because most properties adjoin bushland, wash water is bunded, vacuumed and taken off site, and we plan the order of work so that nothing runs toward drainage lines or the national park boundary.

Sealing in deep shade is a judgement call. Terraces and steps near the house, where people walk and leaves fall, usually benefit from a breathable penetrating sealer that helps water bead and makes sweeping more effective. Retaining walls and outcrops are typically left unsealed so moisture can escape. Sealer only goes on once the stone is fully dry, and in shaded areas that can take several fine days, so sealing is often a second visit. We show you trial finishes before committing, keep the stone's natural grip, and leave a record of what was applied. A yearly look at the terraces is enough for most properties here.