Cleaning a balcony looks like cleaning any other paved area. It is not, because there is a waterproofing membrane under the tiles, a drain that may or may not work, and in most cases somebody living directly below.
Check the drain first
Before any water goes on the balcony, find the drain and confirm it flows.
Pour a bucket of water near it and watch. If it drains slowly or ponds, stop. Washing a balcony with a blocked drain floods it, and the water goes over the edge, under the door threshold, or through a failed membrane into the unit below.
Balcony drains block with leaf litter, pot plant soil, hair and general debris. Most clear with a gloved hand and a flush. If it does not clear, that is a plumbing job before it is a cleaning one.
Also check the fall. Balconies are laid to drain toward the outlet, and if water runs toward the door instead the problem is construction and no amount of cleaning fixes it.
No pressure washer
The firmest rule on a balcony.
High pressure forces water into tile joints, under the tiles and into the waterproofing membrane. A membrane with water getting under it fails, and a failed balcony membrane is a five-figure repair involving lifting every tile.
It also drives water past the door seal and over the edge onto whatever is below — a neighbour’s washing, their furniture, or their open window.
Low pressure, a mop and a brush does the job on a surface this size.
The method
- Clear everything off and sweep thoroughly, including under furniture and in the corners.
- Check and clear the drain.
- Check the sealant around the door threshold and the perimeter. Gaps are a water path.
- Look over the edge. Tell the neighbour if you are about to wet their balcony.
- Apply cleaner — pH-neutral for stone tiles, mild alkaline for porcelain, dilute hypochlorite for mould.
- Agitate with a soft brush, work in sections.
- Rinse with modest volumes of water, working toward the drain, not over the edge.
- Squeegee or mop up the excess rather than letting it find its own way.
Which cleaner suits which tile is in how to clean outdoor tiles.
The usual problems
Black mould in the grout, especially on a shaded or south-facing balcony. Dilute hypochlorite and a grout brush.
Rust rings from furniture feet and pot stands. Needs a rust remover matched to the tile — here. Plastic glides prevent it recurring.
Soil staining under pot plants. Lift the pots onto feet so water drains rather than sitting.
Efflorescence — white bloom in the joints. Often a sign water is getting under the tiles and should be investigated, not just brushed off.
Salt film on the glass balustrade on a coastal building — a different problem, covered in salt film vs hard water staining.
Tea staining on stainless fixings — and crucially, keep hypochlorite off them, because it makes it permanent. Here.
Who owns what
In a strata building this matters before anyone starts.
Generally the slab, the membrane and the balustrade are common property, and in many schemes the tiles are too. Which means a tile lifted or a membrane damaged during a clean is not a straightforward conversation.
It also means persistent water ingress to the unit below is usually a scheme issue rather than a lot owner one.
Set out properly in cleaning an apartment balcony: drainage, neighbours and who actually owns it.
Soffits and the underside
If you can see the underside of the balcony above yours, look at it occasionally. Rust staining, cracking or flaking concrete on a soffit is concrete cancer, and on a coastal building it is common. Report it rather than cleaning it.
For building-wide work, see balcony cleaning.
