How to Install a Floating (Wall-Hung) Bathroom Vanity

Photo by Amira Aboalnaga on Unsplash (https://unsplash.com/photos/1576698483491-8c43f0862543)

By Steve — flooring and wet-areas, Adelaide Hills.

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, and the stone top came off the wall and broke the toilet on the way down. That was a $4,200 insurance claim.

The fundamental problem: Aussie wall-hung vanity brackets are rated to 100 kg per 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 (the horizontal timber blocking) anywhere near where the vanity bracket needs to go. So the right way to install a wall-hung vanity is to open the wall, put a noggin in, re-sheet, then mount.

It sounds like a big job. It’s a 2-hour add-on. And it’s the difference between a 20-year vanity and a $4,200 incident. Here’s how I run it.

What you’ll need

Stud finder (Bosch GMS 120 or similar)
Multi-tool with Gyprock blade (Bosch PMF, Makita TM3010C, Ozito MTK)
Cordless drill + impact driver
90×35 mm F7 pine offcut (Bunnings, structural pine) — at least 600 mm long
14g x 75 mm batten screws
10 mm Gyprock sheet — small offcut, or buy 600×900 sheet from Bunnings
Gyprock screws (32 mm)
Joint compound (Boral Cornice Cement or USG Easy Sand 45)
Mesh joint tape
Spirit level (1200 mm)
The vanity’s bracket and supplied bolts
Pencil, measuring tape, safety glasses, dust mask (P2)

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, 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 marked on the back; some Bunnings imports don’t, and you have to dry-fit the bracket and measure.

Step 2: Find the studs in the wall

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 — you’d be drilling into brick and the fixings are different (use Ramset DynaBolts straight into brick, that’s the whole job). The noggin method is for stud-frame internal walls, which is most Aussie bathroom walls.

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 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/cold water lines or PEX pipes 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. Tomo’s saved me from cutting a 15 mm copper at least twice.

Step 4: Confirm what’s in the cavity, 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 the noggin up/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.

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 around. Screw it to the noggin and the studs with Gyprock screws (32 mm) at 200 mm centres. Set the screw heads just below the Gyprock surface, not torn through.

Step 6: Mesh tape and one coat of joint compound

Apply mesh tape over all four edges of the patch. One coat of joint compound, 100 mm wide, feathered. Let it dry overnight. Sand. Second coat, 200 mm wide, feathered. Sand. You don’t need a perfect finish here because the vanity will cover most of it — but the bracket area needs to be flat or the bracket sits skewed.

If the wall is tiled and the vanity is going on tile, this article changes — you need to cut tiles, but the noggin still goes in behind. Most Aussie wall-hung vanities install on un-tiled or partially-tiled walls.

Step 7: Mark and drill the bracket bolt holes

Hold the bracket up to the wall, level it (the long spirit level is critical here), mark each bolt hole with pencil through the bracket. Step back and double-check level — a vanity that’s 2 mm out over 1200 mm looks crooked.

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.

Step 8: Hang the vanity, plumb in, silicone

Lift the vanity onto the bracket (two-person job, even a 600 mm vanity is 40 kg with a stone top). The bracket should engage cleanly. Lock the vanity to the bracket with the supplied retaining screws (usually two grub screws underneath, accessible from inside the cabinet).

Plumb the basin 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 in a wet area grows mould inside 6 months.

Step 9: Test the load with your own weight

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 — pull it apart and check the screws.

I do a 50 kg test (sit on the edge briefly) before signing off. If the bracket is properly into the noggin, 50 kg is nothing.

Step 10: Document it for the next person

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.

Step 11: Inspect the plumbing connections after 24 hours

Wall-hung vanities load the plumbing differently to floor-mounted ones — the basin sits at a slightly different height and the trap geometry changes. Check the trap and tap connections after 24 hours of use. Run the basin full, drain, listen for gurgles. Look under the trap for any drip. Run a paper towel along every connection — wet paper towel = leak.

Most wall-hung vanity leaks aren’t structural; they’re plumbing connections that worked themselves loose during the install while you were levering the cabinet onto the bracket. Re-tighten as needed.

Step 12: Add the Steve insurance addendum

I write the install date on the inside of the cabinet door in pencil, along with my name and the noggin position. Five years later when something needs servicing or someone questions the install, the record is there. I’ve been called back to a vanity 8 years after install — the pencil note told me what I’d done, the warranty was still good on the bracket, and the homeowner saved a $400 plumber call-out because we already knew what was behind the wall.

The Steve rule

The Steve rule for floating vanities is: 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. Do it once, do it right, the wall does the work.

Got a wall-hung vanity install (or a failure) worth sharing? Send us a write-up.