How to Install a Floating (Wall-Hung) Bathroom Vanity
I get sent at least one floating vanity job a month where the previous installer hung an 80 kg stone-top wall-hung from Reece into nothing but Gyprock and a couple of plastic anchors. The vanity didn’t fail straight away. It failed at month four, when the third bracket let go in the middle of the night, the stone top came off the wall and broke the toilet on the way down. That was a $4,200 insurance claim and a very expensive 3am wake-up. The fundamental problem: Aussie wall-hung vanity brackets are rated to 100 kg under AS 1428 — but only when they’re fixed into solid timber blocking. Into Gyprock alone they pull out at 30 kg. Most Aussie bathrooms don’t have a noggin anywhere near where the vanity bracket needs to go. The right way is to open the wall, install a noggin, re-sheet, then mount. Sounds like a big job. It’s a 2-hour add-on. Twenty years on the tools and I still see installers skip this step every week. Do it once, do it properly, and the wall does the work for the next 25 years.
What you’ll need
- A stud finder (Bosch GMS 120 or similar) — see how to use a stud finder properly first if you’ve never used one
- A multi-tool with a Gyprock blade (Bosch PMF, Makita TM3010C, Ozito MTK)
- A cordless drill plus an impact driver
- A 90×35 mm F7 pine offcut from Bunnings (structural pine) — at least 600 mm long
- 14g x 75 mm batten screws
- 10 mm Gyprock sheet — a small offcut or a 600×900 mm sheet from Bunnings
- 32 mm Gyprock screws
- Joint compound (Boral Cornice Cement or USG Easy Sand 45)
- Mesh joint tape
- A 1200 mm spirit level
- The vanity’s bracket and supplied bolts
- Pencil, tape measure, safety glasses, P2 dust mask
- Selleys Wet Area or Sika Sanisil silicone for the final perimeter bead
Step 1: Confirm the vanity height before you cut anything
Standard Aussie wall-hung vanity height is 850 mm from finished floor to the top of the stone. The bracket sits roughly 700 mm up. Hold the vanity (with a mate) where it’ll go, mark the top, then mark where the bracket bolts will land. Get this measurement now or you’ll be cutting a noggin into the wrong spot. Caroma, Reece’s Posh range and Kaboodle vanities all have the bracket position printed on the back; some Bunnings imports don’t, and you’ll need to dry-fit the bracket and measure. Measure twice. The number of leak callbacks I’ve done because someone cut a noggin too low and then had to do it again would shock you.
Step 2: Find the studs in the wall behind the vanity
Aussie bathroom walls behind a vanity are usually single-stud frame at 450 mm centres. Run the stud finder across the wall at the bracket-bolt height. Mark the studs with pencil — you’ll need to fix the noggin between two studs. If the wall is brick veneer (single-skin internal), this whole article doesn’t apply. Drill straight into brick with Ramset DynaBolts and skip the noggin step entirely. The noggin method is for stud-frame internal walls, which is most Aussie bathroom walls built post-1960.
Step 3: Cut a window in the Gyprock between the studs
Mark a horizontal rectangle between the two studs at the bracket-bolt height. Make it about 500 mm wide and 200 mm tall. Use the multi-tool with the Gyprock blade — set the depth to 11 mm (Gyprock is 10 mm) so you don’t accidentally cut into pipes or wires behind. WET AREA WARNING: there is a non-trivial chance of hot or cold water lines, or PEX, running vertically behind a bathroom wall, especially if a basin tap was previously there. Before cutting, push a long screwdriver gently through a 10 mm pilot hole and feel for resistance. If anything moves, stop, get a borescope down the hole and look. My apprentice Jacob nearly cut a 15 mm copper line on a job in Bridgewater because he forgot this step — saved at the last second by a tap of the screwdriver. Cheap lesson.
Step 4: Confirm the cavity is clear, then fit the noggin
Look in the hole. You should see the back of the next sheet, two stud edges and (hopefully) air. If pipes or wires are in there, you’ll route the noggin around them or move it up or down 50 mm to clear. Cut the 90×35 F7 pine to fit snugly between the studs. Tap it in level. From the side (through the Gyprock window) drive 14g x 75 mm batten screws on a slight angle into each stud — two screws each side, top and bottom. The noggin should be rock solid before you go any further.
Step 5: Re-sheet the window with new Gyprock
Cut a piece of 10 mm Gyprock to fit the window with a 5 mm gap all round. Screw it to the noggin and the studs with Gyprock screws (32 mm) at 200 mm centres. Set the screw heads just below the surface, not torn through. If the screw spins out, move 25 mm along and re-set. A torn screw hole won’t hold and the joint compound won’t hide it.
Step 6: Mesh tape and joint compound the patch
Apply mesh tape over all four edges of the patch. One coat of joint compound, 100 mm wide, feathered. Let it dry overnight. Sand lightly. Second coat 200 mm wide, feathered, dried, sanded. You don’t need a perfect finish here because the vanity will cover most of it — but the bracket area itself needs to be flat or the bracket sits skewed and the vanity sits crooked. If the wall is tiled, this changes — you need to cut tiles, but the noggin still goes behind. Most Aussie wall-hung vanities install on un-tiled or partially-tiled walls.
Step 7: Mark and drill the bracket bolt holes precisely
Hold the bracket up to the wall, level it (the 1200 mm spirit level is critical here), mark each bolt hole with pencil through the bracket. Step back and double-check level — a vanity 2 mm out over 1200 mm looks definately crooked from the doorway. Pre-drill 4 mm pilots into the patch. The bolts will go through Gyprock and into the noggin behind. Use the bolts supplied with the vanity (usually M8 coach bolts) — drive them in with the impact driver on medium torque, finish with a manual ratchet so you can feel the bite.
Step 8: Hang the vanity, plumb it in, silicone the perimeter
Lift the vanity onto the bracket — a two-person job even on a 600 mm vanity. The bracket should engage cleanly. Lock to the bracket with the supplied retaining grub screws underneath. Plumb tap and waste in. Run a 5 mm bead of neutral-cure silicone (Selleys Wet Area or Sika Sanisil) along the back-top edge where the vanity meets the wall. Sanitary-grade only — general-purpose silicone grows mould inside 6 months. See how to re-silicone a bathroom properly.
Step 9: Load-test the install before signing off
Wash hands. Lean on the vanity. Push down hard. It shouldn’t move, click or creak. If it does, you’ve got a bracket-to-noggin issue and you need to pull it apart and check the screws. I do a 50 kg test (sit on the edge briefly) before signing off on any wall-hung install I do for a customer. If the bracket is properly into the noggin, 50 kg is nothing. Then check the plumbing under the cabinet — paper towel along every connection, look for damp. Wall-hung vanities load plumbing differently to floor-mounted ones because the trap geometry changes slightly.
Step 10: Document the install and check at 24 hours
Take a photo of the open wall before you re-sheet — noggin position, screw locations, any pipes you routed around. Email it to the homeowner. In 10 years when someone wants to renovate, that photo is gold. Costs you nothing, saves the next plumber 30 minutes of poking around. Write the install date on the inside of the cabinet door in pencil. After 24 hours of normal use, check the trap and tap connections again — most wall-hung vanity leaks aren’t structural, they’re plumbing connections that worked themselves loose during the install while levering the cabinet onto the bracket. Re-tighten as needed.
When to call a tradie
The carpentry and bracket install is squarely a homeowner job for anyone with basic tools and confidence. The plumbing connections — basin tap, P-trap, hot/cold isolators — are restricted work in most Australian states. A licensed plumber needs to make those connections if any pipe modification is required, and they issue the Certificate of Compliance. The waterproofing layer behind the vanity is also licensed work under AS 3740 — anything that breaks the waterproof membrane on a real bathroom is a licensed waterproofer’s job. Don’t cut into the membrane chasing a stud; locate the noggin in clear unmembraned wall above the splash zone.
Common screw-ups
- Hanging a wall-hung vanity into Gyprock with plastic anchors — the classic 3am stone-top failure.
- Cutting the Gyprock window without checking for pipes — slow screwdriver-poke test first, every time.
- Mounting the bracket without levelling — 2 mm out over 1200 mm looks crooked from the doorway.
- Using general-purpose silicone on the perimeter bead — mould in 6 months, redo in 12.
- Skipping the 50 kg load test — first failure happens at month four in the middle of the night.
Cost & time
F7 pine offcut: $8. Gyprock offcut, screws, joint compound: $30. Silicone: $14. Total carpentry add-on: about $50 and 2 hours over two days (an overnight dry on the joint compound). Compare against the $4,200 insurance claim if the vanity falls. The whole vanity install with noggin prep takes 4–5 hours of actual work spread across 2–3 days because of dry times. A trade install on top of an existing-prepped wall is $250–$400 in metro Adelaide.
No noggin, no install. AS 1428 is clear — wall-hung fixtures need solid blocking. Gyprock anchors aren’t blocking. Plastic toggles aren’t blocking. A 2-hour add-on to put a 90×35 pine noggin in the wall is the difference between a vanity that lasts 25 years and a 3am stone-top-on-the-toilet incident that nobody wants to be woken by. Twenty years on the tools and I still see installers cutting this corner; the houses where the noggin went in are the houses I never get a callback from. The wall does the work — give it something to work with. Do it once, do it properly.
