How Much Does It Actually Cost to Replace Windows in NZ?

Replacing your windows isn't just about picking something that looks nice. It's one of those home upgrades where the numbers can swing wildly depending on what you choose - and what you didn't know you needed.

If you're trying to budget for new windows, here's what actually affects the price, and what you should expect in 2026.

The Ballpark: Cost of Windows in NZ

Let's start with the basics. For standard double-glazed aluminium windows, you're looking at roughly $800 to $1,500 per square metre installed. That's your mid-range option - decent quality, thermal performance, and longevity.

Here's how different types stack up:

• Aluminium double glazed: $800–$1,500/m² 

• uPVC double glazed: $900–$1,600/m² 

• Timber double glazed: $1,200–$2,200/m² 

• Retrofit double glazing (adding to existing frames): $400–$800/m²

Custom shapes, larger sizes, or architectural designs? Add 20–40% to those numbers.

What Actually Drives the Cost Up

Window Size and Configuration

A standard bedroom window might be 1.2m², costing around $1,200 installed. But a 3m-wide sliding door? That's $3,500–$5,000 easily. The bigger the glass, the higher the spec required for safety and performance.

Frame Material Matters

Aluminium is the workhorse of NZ windows - durable, slim sightlines, low maintenance. uPVC costs slightly more but offers better thermal performance out of the box. Timber looks beautiful but needs more care and comes at a premium.

Glass Specification

Basic double glazing is standard now, but there's a range:

• Standard double glazing: 4mm glass with 12mm air gap

• Low-E coating: Adds $80–$150/m² but cuts heat loss by 30%

• Argon-filled: Another $50–$100/m² for even better insulation

• Acoustic glass: From $200/m² extra if you're near busy roads.

Labour and Installation

Installation typically runs $200–$400 per window, depending on access, whether you need structural work, or if it's a simple swap-out. Older villas with non-standard sizes? Expect the higher end.

Other Costs You May Not Be Aware Of

• Building consent: For full window replacements (not just glass), you'll likely need consent. Budget $500–$1,500 depending on your council.

• Retrofitting trim and reveals: Old window openings rarely match new sizes perfectly. Allow $150–$300 per window for carpentry work.

• Disposal: Removing old windows and frames isn't free - around $50–$100 per window.

• Painting or staining: If you're going timber, factor in finishing costs.

Retrofit Double Glazing: The Budget Option?

If your frames are in good nick, retrofit double glazing can be tempting at $400–$800/m². You keep the existing frames and just upgrade the glass.

The upside: Cheaper and faster.

The catch: Your old frames might not be thermally broken, so you're still losing heat through the aluminium. And if the frames are 20+ years old, you're putting new glass in aging systems that might fail soon anyway.

For most homes, full replacement makes more sense long-term - especially with modern thermally broken systems that dramatically cut condensation and heat loss.

Should You Use a Cost Calculator?

Online double glazing cost calculators can give you rough numbers, but they're only as good as the info you put in. They won't account for:

• Tricky access or scaffolding needs

• Non-standard sizes or custom work

• Building Performance requirements for your climate zone

• Structural repairs if your frames have rotted

Get at least three quotes from licensed manufacturers. Ask specifically about thermal performance (R-values), what's included in the install, and warranty terms.

Tips to Keep Costs Sensible

• Bundle the job: Replacing all your windows at once saves on setup and consent costs compared to doing it room by room.

• Don't over-spec where you don't need to: Acoustic glass in a bedroom facing a quiet backyard? Probably unnecessary.

• Check for council grants: Some councils offer rates relief or grants for energy-efficient upgrades.

• Plan around your build: If you're renovating anyway, factor windows into the main consent to save double applications.

Quality vs. Price

Here's the thing about windows: they're a 20-30 year investment. Skimping to save $2,000 now could mean condensation, heat loss, and early failure.

Look for:

• Thermally broken frames (essential in NZ's climate)

• Proper weatherseals (not just cheap brush strips)

• Decent warranties (10+ years on frames, 5+ on seals)

• Compliance with NZ Building Code

A licensed Altherm manufacturer, such as Phoenix Windows & Doors, meets these standards as a matter of course. These systems are specifically tested for New Zealand conditions, including wind, rain, UV exposure, and seismic activity.

What About DIY?

Unless you're a licensed builder with joinery experience, don't. Window installation affects your building's weathertightness and structural integrity. Poor installation voids warranties and can lead to leaks, rot, and expensive repairs.

Plus, you need the work signed off by a Licensed Building Practitioner to meet Building Code requirements.

The Real Question: Is It Worth It?

If your current windows are single-glazed or more than 25 years old, the energy savings alone can be significant. The Building Performance website estimates that double glazing can reduce heat loss through windows by 50-60%.

That's lower power bills, a warmer home, and better condensation control. In many cases, windows pay for themselves over 10-15 years - especially if you're in a colder region.

Final Pricing Example

Here's what a typical 3-bedroom house might cost:

1. 8 standard windows (average 1.5m² each): $14,400

2. 2 bedroom doors with glass (2.5m² each): $6,000

3. 1 large living slider (4m²): $5,600

4. Installation and building consent: $3,500

Total: $29,500

That's for good-quality aluminium double glazing with Low-E coating. Go uPVC or timber, and you're pushing $35,000–$42,000.

Getting Started

Get quotes from licensed manufacturers like Phoenix Windows and Doors who work with proven systems. Ask us about:

• Exact specifications (glass type, frame material, thermal performance)

• Installation timeline and what's included

• Building consent handling

• Warranties and after-sales service

And remember - windows aren't just about today's price tag. They're about comfort, energy bills, and home value for decades to come.

For more on choosing the right windows and entrance doors for your project, check out our other guides.