10 Common Bathroom Renovation Mistakes (and How to Avoid Them)
Meta description: Avoid wasting money on your bathroom reno. Here are the most common design and planning mistakes NZ homeowners make.
A bathroom renovation can boost the value and comfort of your home—but it’s also easy to get it wrong. From poor planning to choosing the wrong materials, these missteps can cost you thousands or leave you with a space that doesn’t function well.
Here are the 10 most common bathroom renovation mistakes NZ homeowners make—and how to avoid them.
1. Not Planning the Layout Properly
One of the biggest regrets we hear is around layout. Whether it’s squeezing in a bath that makes everything else feel cramped, or having the toilet as the first thing you see when the door opens, poor flow can ruin the space.
Tip: Always start with the layout. Think about sight lines, movement, and how you use the bathroom daily.
2. Underestimating Waterproofing Requirements
Waterproofing isn’t just a checkbox—it’s the foundation of a long-lasting bathroom. Poor waterproofing leads to rot, mould, and expensive repairs.
Tip: Ensure your builder follows NZ Building Code regulations and uses certified waterproofing membranes in all wet zones.
3. Choosing the Wrong Tiles or Grout
High-gloss floor tiles can be slippery, and cheap grout discolours quickly in high-moisture areas.
Tip: Choose slip-rated tiles for floors, especially in showers, and always opt for epoxy grout in wet areas for longevity.
4. Trying to DIY Beyond Your Skill Level
Attempting to tile, waterproof, or plumb yourself without experience can backfire badly.
Tip: Save the styling for yourself, but leave critical trade work to licensed professionals. It protects your warranty—and your resale value.
5. Blowing the Budget on Looks, Not Function
It’s tempting to splurge on feature tiles or a statement vanity, but neglecting ventilation, lighting, or water pressure can ruin the result.
Tip: Invest first in core infrastructure—then choose stylish finishes that complement your layout and function.
6. Poor Storage Planning
Many renovators forget about storage until it’s too late. The result? Benchtop clutter.
Tip: Integrate storage early—think mirrored cabinets, wall nooks, floating vanities, and tower units that suit your lifestyle.
7. Using Non-Bathroom Rated Materials
Some materials, like MDF cabinetry or untreated steel fittings, simply aren’t made for moisture.
Tip: Always use materials rated for wet areas—think moisture-resistant board, powder-coated finishes, and sealed benchtops.
8. Skipping the Ventilation Upgrade
If you don't improve the fan, you're asking for mould—no matter how nice your new tiles look.
Tip: Upgrade to a high-powered extraction fan with ducting to the exterior. Consider humidity sensors for automatic control.
9. Not Future-Proofing the Design
What works today might not work in 10 years—especially for growing families or ageing homeowners.
Tip: Design with accessibility and resale in mind. Level-entry showers, wall-hung vanities, and smart tapware are safe bets.
10. Not Getting a Fixed-Price Quote
Many Kiwis start with a ballpark figure, only to be hit with cost blowouts later.
Tip: At Key Interiors, we offer transparent, fixed-price quotes with full scope details so there are no surprises.
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Frequently Asked Questions
What’s the biggest bathroom renovation mistake?
The most common mistake we see is poor layout planning—especially when homeowners don’t engage a designer early. It impacts everything from flow to lighting and functionality.
Can I save money by doing the bathroom renovation myself?
Only if you're experienced. Waterproofing, tiling, and plumbing are best left to professionals—DIY mistakes can void insurance or cause major issues.
What materials should I avoid in a NZ bathroom?
Avoid materials not rated for moisture, like untreated MDF, standard paint, or unsealed grout. These deteriorate quickly in humid bathrooms.
How do I make sure my waterproofing is compliant?
Hire a qualified builder and check they follow NZ Building Code E3 and AS 3740. Ask for a Producer Statement and photos of membrane install.
Where should I start if I want to renovate?
Start by booking a free consultation with Key Interiors. We’ll help you plan a layout that works, select the right materials, and avoid costly pitfalls.