Waterproofing — Who's Responsible?

Waterproofing is one of the most expensive and most argued-about items in strata — and townhouse schemes are genuinely different from apartment buildings here. In apartments, almost all waterproofing is common property. In townhouses, the answer often depends on where the leak is, what the strata plan actually shows, and whether a common property rights by-law has ever been registered.

What we're talking about

Waterproofing isn't just one thing. In a townhouse, it includes:

• Membranes — the hidden layer that stops water passing through a slab or surface
• Flashings — strips of metal or rubber where surfaces meet (windows, doors, roof edges)
• Sealants and caulking — around bathroom fittings, kitchen sinks, external joints
• Drainage — drains, gullies, falls in the substrate
• Wet area waterproofing — under bathroom and laundry tiles

Most waterproofing problems are found after water has already shown up somewhere it shouldn't. Ceilings stain, walls bubble, mould appears, timber rots. By then it's a bigger job than catching it early.

Typical position

Grey areas and common disputes

Who pays for lifting the tiles?

This is the question that causes most arguments. If a membrane fails under a balcony, the membrane is OC's to fix — but to get to it, the tiles or paving on top (lot property) need to come off. The position is usually:

• The OC pays to remove and reinstate finishes that were damaged by the membrane failure itself.
• If the original finishes are simply in the way of accessing the membrane, the cost is sometimes split — but this varies and is often disputed.
• If the lot owner wants an upgraded finish (better tiles, different pavers), they pay the difference.

This is rarely a clean conversation. Get the position in writing from the strata manager before the work starts.

Bathroom waterproofing in a townhouse

This is where the townhouse vs apartment difference matters most. The correct way to work it out is in two steps:

1. Read the strata plan. Most townhouse strata plans use a "building format" or older style of boundary that shows the lot extending to the outside surfaces of the building. If the strata plan shows the lot including the floor slab, the bathroom membrane inside that slab is your responsibility — not the OC's. If the plan shows the slab itself as common property, the membrane in or on it is common property and the OC must repair it.
2. Check for by-laws. If a previous owner renovated the bathroom, they may have registered a "common property rights by-law" that shifts maintenance of new waterproofing back to the lot owner. These by-laws bind future owners, so even if you didn't do the work, you may be responsible. If no by-law was registered for a renovation that touched common property, the position can be messy.

For everyday leaks, the practical rule is: sealant around the bath, basin, shower screen and kitchen sink is the owner's responsibility. That covers maybe 80% of bathroom leaks reported in townhouses — failed silicone, not failed membrane.

Bathroom renovations by previous owners

If a previous owner renovated their bathroom and a common property rights by-law was registered at the time, that by-law usually puts ongoing maintenance of the new waterproofing on the lot owner — and that obligation passes to whoever owns the lot next. If no by-law was registered and the work touched common property, you may be left with the original responsibility position. Either way, it pays to check the by-laws on title before assuming who has to fix what.

External membrane replacement

Replacing an external above-ground waterproofing membrane (over a balcony, for example) is not as simple as it sounds. It usually needs proper development approval, not just a contractor turning up. The work has to comply with current Australian Standards, which many older buildings don't meet without major changes. The OC needs a proper specification from a building consultant before quoting the work.