Bathroom layout and waterproofing basics

Layout and clearances

Clearances, sightlines, and zones

Plan the layout before any fixture is chosen. Leave comfortable clearance in front of the toilet and vanity, keep the toilet out of the direct sightline from the door, and make sure the door, including a shower door, opens without hitting anything. Separate the wet zone, the shower and bath, from the dry zone, the vanity and toilet, so the whole room does not get soaked in daily use.

Dimensions cheat sheet

Set these before fixtures are ordered; they decide whether the room passes a walk-through without elbows hitting glass.

Waterproofing and moisture

Waterproofing is a certified step, not a finish

Waterproofing in Australian bathrooms is governed by the relevant standard and is a regulated part of the build, not a coat you brush on for looks. A licensed waterproofer applies the membrane to the specified areas, the floor is graded so water runs to the 'floor waste', and the work is documented and certified. Failed or skipped waterproofing is one of the most expensive defects to fix, because it means pulling the finished room apart.

Ventilation

A sealed, poorly ventilated bathroom grows mould no matter how good the waterproofing is. Specify an exhaust fan sized to the room and vented outside, not just into the ceiling cavity, and run it long enough after showers to clear the moisture. Good ventilation protects the finishes, the paint, and the air quality.

Size the fan to the room rather than buying whatever the sparkie has on the van: for a typical domestic bathroom, aim for a unit that changes the air fifteen to twenty times an hour, and duct it to outside air.

Falls and drainage

Water leaves a bathroom floor by design, not luck. The screed under the tiles is graded so the general floor falls at about 1:80 to the floor waste and the shower floor at about 1:50, and that setout happens before tiling day.

Niche and shower screens

A recessed niche keeps bottles off the floor without a shelf in the spray. Size it to the tile courses, one or two courses high and 300 to 600 mm wide, set between 900 and 1200 mm above the floor, and keep it out of external walls where possible. The screen then decides how open the room feels.

Bathroom lighting

Light the mirror, not just the ceiling

A single overhead downlight puts your face in shadow at the exact spot you shave or do makeup. Put task light at the mirror, wall lights either side at eye level or a quality LED mirror, and treat the downlights as the ambient layer. Specify 2700 to 3000 K throughout and a CRI of 90 or better at the mirror, where you judge skin tone.

Wet-area zones and IP ratings

The wiring rules divide a bathroom into zones around the shower and bath, and each zone limits what may be installed there. Fittings in and over the shower need a suitable ingress protection (IP) rating; confirm the rating with every fitting you select, and let your electrician map the zones at rough-in. The exhaust fan is part of the plan too, ducted outside, not into the roof cavity.

A bathroom above someone else's ceiling is the highest-liability room in a strata scheme, because a failed membrane travels down. Renovating one almost always needs scheme approval before work starts, with the waterproofing done by a licensed applicator and the certificate lodged with the owners corporation (OC) or body corporate.

Check the by-laws for acoustic conditions on pumps and pipework, confirm whether relocating fixtures counts as a major renovation, and build the approval time into the program before trades are booked.

Brief your waterproofer

Waterproofing fails on shortcuts, not products. Put these four lines in writing: