What certified AS 3740 waterproofing actually involves, and why it's the most important $5,000 in your renovation.
Waterproofing is the single most consequential trade in a bathroom renovation. Done well, it disappears for decades. Done poorly, it shows up as failed showers, rotted joinery and insurance claims.
AS 3740 sets minimum requirements: full shower floor and 1800mm up the walls, full bathroom floor, all penetrations sealed. A premium specification goes further — bonded waterproof sheet to substrate, full bathroom wall coverage, primed and mesh-reinforced corners.
Always insist on documentation: photos of every stage and a certificate on completion. We provide both on every job.