Yes, you can install a towel rail or robe hook into a hollow wall — but only if you use the right fixing method for the wall type and the load it will carry. A poorly fixed rail can pull out of the wall, causing damage and potential injury, so it pays to take a few minutes to plan before you drill.
Understanding What's Behind Your Wall
Most NZ homes have interior walls lined with plasterboard (GIB board), typically 10 mm or 13 mm thick, fixed to a timber framing system built to NZS 3604. The plasterboard itself has very little holding strength on its own — the real strength comes from the timber studs behind it, which are usually spaced at 400 mm or 600 mm centres.
Before you fix anything, you need to know:
- What the lining is made of — plasterboard, fibre cement, or timber panelling
- Where the studs are (if any)
- Whether there are any pipes or cables hidden in the wall cavity
Finding Studs and Avoiding Hidden Services
Use a stud finder (available from Bunnings or Mitre 10) to locate timber framing. Mark the stud positions lightly with a pencil. Fixing directly into a stud is always the strongest and most reliable option — a 65 mm timber screw driven into a stud will hold a heavily loaded towel rail with ease.
Before drilling, check for hidden electrical cables and water pipes. In bathrooms especially, pipes and wiring can run through wall cavities. A basic cable and pipe detector is a worthwhile investment. If you're at all unsure, consult a licensed tradesperson.
Safety note: In New Zealand, any work on electrical wiring is restricted work and must be carried out by a registered electrician licensed under the Electrical Workers Registration Board (EWRB). Similarly, plumbing work is restricted under the Plumbers, Gasfitters and Drainlayers Board (PGDB). Do not drill blindly into bathroom walls without checking for services first.
Fixing Options When You Can't Hit a Stud
If your towel rail or hook doesn't line up with a stud, you have several good options:
1. Hollow-Wall Anchors (Cavity Fixings)
These expand behind the plasterboard as you tighten the screw, gripping the back face of the board. Common types include:
- Plasterboard plugs — suitable for light loads like a single robe hook
- Metal toggle bolts — stronger, good for towel rails with moderate loads
- Nylon spring toggles — easy to install, reasonable holding strength
Always check the manufacturer's rated load for the anchor you choose, and match it to the weight the fitting will carry. A towel rail loaded with wet towels can be surprisingly heavy.
2. Timber Backing Nogging
If you're renovating or have wall access, the best long-term solution is to have a nogging (a horizontal timber block) fitted between the studs at the right height. This gives you a solid fixing point anywhere along that section of wall. A joiner or builder can add noggings during a renovation — it's a small job that makes a big difference.
3. Surface-Mounted Backing Plate
For heavier rails (such as a heated towel rail bracket), a timber or plywood backing plate can be surface-fixed across two studs, then the rail fixed to the plate. This spreads the load and looks tidy if painted to match the wall.
Step-by-Step: Installing Into a Hollow Wall
- Mark your fixing positions using a spirit level to keep everything straight.
- Check for studs, cables and pipes with a detector.
- Choose the right fixing based on load and wall type (see table below).
- Drill a pilot hole the correct diameter for your anchor — check the packaging.
- Insert the anchor and fix the rail or hook bracket firmly.
- Test the fixing by applying firm hand pressure before hanging anything on it.
| Fixing Type | Best For | Approx. Load Rating | Stud Needed? |
|---|---|---|---|
| Timber screw (65 mm) | Any bracket | High | Yes |
| Metal toggle bolt | Towel rails | Medium–High | No |
| Plasterboard plug | Robe hooks | Light–Medium | No |
| Nogging + screw | Permanent rails | High | No (nogging required) |
Load ratings vary by product — always check the manufacturer's specifications.
Bathroom-Specific Considerations
In bathrooms, GIB Aqualine or similar moisture-resistant plasterboard is often used. This is still a hollow-wall system and the same fixing principles apply. However, if your bathroom has tiled walls, you'll need a tile drill bit and appropriate tile anchors — drilling through tiles requires care to avoid cracking them. Consider getting a tiler or joiner to help if you're not confident.
The NZ Building Code (specifically clause E3 for internal moisture (though E3 primarily covers wet area construction requirements — confirm with your council or MBIE guidance how it applies to your specific situation)) requires bathroom linings to be moisture-resistant, so avoid damaging the lining's integrity with oversized holes or poor-quality fixings.
When to Call a Professional
Call a qualified joiner or builder if:
- You need noggings added inside the wall cavity
- You're unsure where cables or pipes run
- The wall is tiled and you're not confident drilling through tiles
- You're installing a heated towel rail — the electrical connection must be done by a registered electrician
- The wall is an unusual material (e.g. fibre cement, masonry, or heritage timber lining)
You can find experienced local joiners and builders on tradedirectory.co.nz.
