Caulking

The cheapest line item on the building, and the one that causes the most water damage.

Sealant is the only thing between the outside and the inside at every window perimeter, every panel joint and every expansion gap on the façade. It has a service life — roughly 10 to 15 years in Sydney's UV and salt air, less on a west-facing elevation — and when it goes, water enters at height and appears three floors down as a ceiling stain nobody can trace.

Recaulking an entire elevation costs a fraction of the internal repairs that follow when it's left.

Where it fails

Window and door perimeters — the most common leak path, and the one usually blamed on the glazing instead

Expansion and control joints — designed to move; sealant that's gone hard can't, so it splits

Precast and panel joints — long vertical runs on concrete panel buildings, fully rope-accessible

Balcony junctions — slab-to-wall and balustrade base fixings where water sits after rain

Roof penetrations and plant — flashings, pipe penetrations and equipment plinths

Why the last recaulk didn't last

Sealant fails early for three reasons, and none of them are the brand.

It was applied over the old bead. New sealant bonds to old sealant, the old sealant lets go, and both come off together. The existing bead has to be cut out completely.

There was no backing rod. Without it the sealant bonds to three sides instead of two and tears itself apart as soon as the joint moves. It also wastes material filling a cavity that didn't need filling.

The joint was dirty or damp. Sealant needs a clean, dry, primed substrate. Gunned into a joint with dust or morning moisture in it, adhesion fails inside a season.