Sandstone cleaning and sealing in Allambie Heights

Most Allambie Heights properties date from the post-war decades, and many have sandstone that has had seventy-odd years to weather. Retaining walls along boundaries, steps cut between garden levels and paved areas around the house are typical, often with natural rock worked into the landscaping. Under the bush canopy, stone tends to be dark: black mould on vertical faces, moss in joints, tannin shadows on paving and lichen on anything exposed. Pool coping collects leaves and the stains that come with them. Our technicians look at each surface, note what is growing on it and test a cleaner on a small patch first, so the full treatment matches what is actually there.

We apply a sandstone-safe biocide to the growth and give it a long dwell, so it is killed at the root rather than just knocked back. Soft brushes lift the dead material, and a gentle rinse finishes the job, with no turbo tips, which would cut into weathered sandstone. Tannin stains are treated with a dedicated cleaner, and those that have soaked deep are drawn out with a poultice. Leaf litter is cleared before we wet anything. Bunds hold the wash water until it is vacuumed up, so it never reaches garden beds bordering the bush or the street drains.

Sealing helps where stone dries between rain: paving, steps, wall caps and coping. A breathable impregnating sealer means tannin and growth take hold more slowly, and leaves sweep away more cleanly. Walls with soil behind them and stone in constant shade are usually left unsealed, because they cannot release moisture fast enough. We seal only stone that is properly dry, which under the trees may mean coming back after a week or so of fine weather, and you see natural and enhanced samples on your own stone first. Results last longer if overhanging branches are thinned and gutters are kept clear, and we note any changes like that which would help.