Quick Answer
A leaking shower is usually caused by failed grout and silicone sealant, cracked tiles, or failed waterproofing membrane behind the tiles. DIY fixes for silicone and grout cost $30â$80 in materials and work well for minor leaks. Full re-waterproofing with retiling costs $1,500â$5,000 and requires a licensed waterproofer under Australian Standard AS 3740. Most shower leaks are fixable â act early before water damage spreads to subfloor or neighbouring rooms.