How Much Does Retrofit Double Glazing Cost in NZ? (2026)
Typical cost in NZ
$16,000
A retrofit double glazing in New Zealand typically costs around $16,000, ranging from $4,000 for a budget job to $60,000+ at the premium end. The figures below break down what each level gets you, what drives the price, and how it varies by region.
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Check a builderRetrofit Double Glazing cost by level
Budget
$4,000 – $10,000
Retrofit double glazing into the main living areas and one or two bedrooms, keeping the existing aluminium or timber frames.
Mid-range
$10,000 – $25,000
Whole-house retrofit for a typical 3-bedroom home (12-15 windows), existing frames in good condition.
Premium
$25,000 – $60,000
Full window replacement with new double-glazed joinery (thermally broken aluminium or uPVC), larger homes or low-E and argon upgrades throughout.
What changes the price
| Factor | Impact | Why |
|---|---|---|
| Retrofit vs full replacement | Roughly half the price | Retrofitting new glass units into your existing frames avoids new joinery, flashings and making good around each opening. |
| Frame condition and material | +$ varies | Sound aluminium frames retrofit easily. Rotten timber frames or warped sashes push you toward full replacement. |
| Glass spec | +10-30% | Low-E coatings, argon fill and laminated or acoustic glass each add cost per unit. |
| Window count and size | Linear | Quotes are built per opening. Large fixed panes and unusual shapes cost more per m² than standard sashes. |
| Access | +$1k-5k | Second-storey windows can need scaffolding or lifts, billed on top of the glazing itself. |
Retrofit Double Glazing cost by region
Indicative cost based on the typical figure, adjusted for regional labour and material differences.
Auckland
$18,000
Wellington
$17,000
Christchurch
$16,000
Hamilton
$16,000
Tauranga
$16,000
Regional NZ
$15,000
What's usually included, and what isn't
Usually included
- Measure and manufacture of sealed double-glazed units
- Removing existing single glazing
- Fitting new units and adapter systems into existing frames
- Resealing and trims
- Disposal of old glass
Usually extra
- Frame repairs or replacement of rotten timber
- Scaffolding for upper-storey access
- Curtain or blind refitting
- Repainting around openings
- New joinery (that is the full-replacement price tier)
Typical timeline
2–10 days
Building consent
Not usually required
Swapping single glazing for double glazing in the same openings is usually exempt under Schedule 1 of the Building Act. You do need consent if openings change size, structure is altered, or you are replacing a window that failed within 15 years of installation.
Read the full consent answerA retrofit double glazing is one of the biggest cheques you'll write.
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Questions to ask before you sign
- Is this retrofit into my existing frames or full joinery replacement, and why?
- What exact glass make-up am I getting per window: gap width, low-E, argon?
- What is the warranty on the sealed units against fogging, and who honours it?
- Have you checked my frames are sound enough to take the heavier units?
- What is the manufacturing lead time before install starts?
Find registered trades near you
Ready to get quotes? Browse registered retrofit double glazing trades by city, then run a background check on each one before you sign.
Frequently asked questions
- How much does it cost to double glaze a whole house in NZ?
- A whole-house retrofit on a typical 3-bedroom home usually lands between $10,000 and $25,000, depending on window count, glass spec and frame condition. Full replacement with new double-glazed joinery runs $25,000 to $60,000 and beyond.
- Do I need building consent to retrofit double glazing?
- Usually not. Like-for-like window work on an existing home is exempt under Schedule 1 of the Building Act. Consent comes into play if you enlarge openings, alter structure, or the original window failed within 15 years of being installed.
- Is retrofit double glazing worth it compared to new windows?
- Retrofitting costs roughly half of full replacement and keeps your existing frames. It suits sound aluminium or timber joinery. If frames are rotten, leaky or warped, paying more for new joinery avoids putting new glass in failing frames.
Retrofit Double Glazing costs by city
Related cost guides
Sources: Canstar NZ double glazing cost guide; Double Glazing Quotes NZ retrofit pricing 2025; Superior Renovations double glazing cost calculator 2026; Building Performance (building.govt.nz) Schedule 1 window exemption. Figures are 2026 estimates for guidance only and exclude GST unless stated, so always get written quotes for your specific project. Last updated 2026-06.