Sandstone cleaning and sealing in North Balgowlah
In North Balgowlah, sandstone sits under trees more often than in the sun. We clean the growth out of it and seal only surfaces that will dry and breathe.
- North Balgowlah 2093
- $20 million public liability
- Price on request
The typical North Balgowlah job is a family home on a sloping block with sandstone in three or four places: a retaining wall along the side boundary, steps down to the back garden, a paved entertaining area and perhaps coping around a pool. The stone nearest the bushland or under large gums is usually darkest, coated in a mix of black mould, green algae and leaf tannin. Wall tops and outcrops carry grey and orange lichen. Areas in full sun are often just dusty. Our technicians walk the property with you, note which surfaces carry which growth and test a cleaner on each before treating the whole area, so the result is even from one end to the other.
Biological growth is the main target, and it is killed rather than blasted off. We apply a stone-safe biocide, let it dwell so it reaches the roots in the pores, then agitate with soft brushes and rinse at low pressure. That approach leaves the surface intact and slows regrowth, whereas a pressure washer removes the visible layer and part of the stone, leaving a rougher face that holds spores. Tannin marks get a separate treatment, or a poultice where they have soaked in. Wash water is contained and vacuumed up, and we keep it off garden beds bordering the bush. Debris we lift is bagged so it cannot wash back onto clean stone.
Shade changes the sealing decision. A breathable sealer suits paving, steps and coping that drain and dry properly, because it holds back tannin and growth, and leaf litter sweeps off a sealed surface more easily. Stone that stays wet for days, such as a retaining wall with soil behind it, is better left unsealed so moisture can escape. We only seal once the stone is properly dry, and under a tree canopy that may mean a return visit after a run of fine weather. We show you natural and enhanced finishes on test patches, log the product and date, and suggest an annual look at shaded areas to catch regrowth early.
Frequently asked questions
Sandstone questions we hear in North Balgowlah.
Will the mould come straight back after cleaning?
Not straight away. Killing it at the root with biocide gives a much longer result than pressure washing. In deep shade some regrowth within one to two years is normal, and more light and airflow extend that.
Why do you clear leaves before starting?
Wet leaves release tannin. If we wet the stone with leaves still on it, we risk creating new stains on surfaces we have just cleaned.
Can sealing stop lichen growing on our wall caps?
It slows it but does not prevent it, because lichen grows on sealed surfaces too. The biocide clean resets it, and a maintenance treatment every few years keeps it under control.
Our pool coping is sandstone. Does the pool need to be drained?
No. We cover or protect the pool, clean the coping from the deck side and keep products and run-off out of the water.