Sandstone cleaning and sealing in Double Bay

Two kinds of sandstone come up most in Double Bay. The first is older stone low on buildings near the water: footings, plinths and steps that sit close to the water table and draw moisture upward, leaving white salt bloom and a crumbly surface on the lowest courses. The second is sandstone on apartment entries and front walls, which collects foot-traffic grime, bin residue and some salt from the air. The first is mainly a moisture and salt problem; the second is mainly a cleaning problem. Telling them apart is the first thing our technicians do, because the treatment, and the advice about sealing, is different for each.

Salt bloom is brushed off dry where possible, then treated, and where salts have built up within the stone, a poultice can draw some of them out. We also look for the moisture source, such as a blocked drain, a garden bed against the wall or a leaking downpipe, because the salts will keep returning otherwise. Grime and organic growth are cleaned with a matched product and a low-pressure rinse, never a high-pressure tip. In the village and on busy streets such as Bay Street and Cross Street, wash water is collected as we go so nothing enters the stormwater system, and footpaths are kept dry and safe for passers-by.

We don't seal sandstone that is actively drawing moisture through its face, because the sealer can trap salts behind it and make the flaking worse. Entry paving, steps and front walls that stay dry from behind are a different matter: a breathable penetrating sealer helps them resist stains and makes routine cleaning far easier for building staff. You see test patches of a natural and an enhancing finish before choosing either. Being local, we can also return to check the stone after the first heavy rain if you would like reassurance that water is beading as it should, and we keep a record of the product so future touch-ups match.