Sandstone cleaning and sealing in Randwick

Most Randwick sandstone we see is on older houses and their grounds: facades, chimneys and window dressings, garden and boundary walls, gate piers and front steps. Away from the sea, the problems are mostly lichen and mould on shaded faces, tannin stains under street and garden trees, rising damp and salt bloom on lower courses, hard cement pointing and, on some buildings, old paint or coatings. Carved and decorative elements show the most weathering, because they have the most exposed surface. We map these on a walk-around before quoting, with photographs, so you can see exactly what we propose for each element and why.

Our technicians test first, then treat growth with a biocide and a generous dwell time before rinsing gently with cool or warm water at low pressure. Loose salts are brushed off dry before water is applied. Any old coating gets a small removal trial with the mildest stripper that might work. Rust and acid stains are drawn out with poultices rather than treated with more acid. Where cement pointing is damaging the stone, we can rake it out and repoint in a soft lime mix, so that future weathering happens in the joint rather than the stone. All run-off is captured and taken away, not washed to the gutter.

Facades and garden walls are generally healthier left unsealed, free to dry after rain and let salts escape at the surface rather than behind it. Steps, paths and paving that take foot traffic and leaf litter benefit from a breathable penetrating sealer, which keeps tannin and spills near the surface where they can be cleaned off. On heritage items, we discuss any sealing with you first, explain why we recommend it or not, and record the product, date and area for your files. That documentation is also useful if Randwick Council or a heritage adviser later asks what treatment the stone has received over the years.