Cost Breakdown
Typical range: $18k-$35k (standard). Factors: proximity to existing plumbing, size, fixtures quality. Ensuite conversions (using existing bedroom space) cheaper than full additions.
Plumbing Stack Proximity
Locate near existing bathroom (minimizes rough-in cost). Long plumbing runs increase labour. Waste stack access critical (concrete slab homes more complex).
Layout Options
Ensuite: Bedroom conversion (2.5x2m typical). Powder room: Under stairs, repurposed laundry (toilet + vanity only, 1.5x1.5m). Full bathroom: Requires 2.5x2.5m minimum.
Ventilation Requirements
Mechanical exhaust mandatory if no window. Ducted to exterior. Minimum 25L/s. Ceiling cavity must accommodate ductwork.
Permits and Compliance
Building permit required (plumbing + waterproofing). Electrical compliance (wet area zones). AS3740 waterproofing certificate mandatory. Timeline: 3-5 weeks construction.
Key Takeaways
- Cost $18k-$35k for standard second bathroom
- Proximity to plumbing stack reduces cost
- Ensuite conversions cheaper than additions
- Mechanical ventilation required if no window
- Building permit mandatory for all bathrooms
Ready to Start?
Adding second bathroom? Get feasibility assessment and quote.