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Double Glazing Cost NZ (2026): Retrofit vs Replacement

Double glazing in NZ costs about $450 to $1,500 per m². Retrofit vs replacement vs secondary glazing, plus consent and heritage rules.

By the GetListed team · Updated · 9 min read

Double glazing in New Zealand costs roughly $450 to $1,500 per square metre supplied and installed, according to Canstar. For a whole house, one Auckland renovation company puts retrofit double glazing at $18,000 to $28,000 for a typical 100m² home, against around $35,000 for full window replacement. The real price depends on how much glass you have, your frames, and the glass you choose.

This guide covers the three main ways to upgrade windows, published per-window and per-m² prices, what the energy agency says you gain, and the consent, Healthy Homes and heritage rules that apply.

You can browse builders across New Zealand on GetListed, then find local providers and contact them directly, with no lead fees.

Double glazing cost in NZ: published prices

No official price list exists, so the figures below come from published guides. Each one is an indicative range, not a quote.

Source What it says
Canstar $450 to $1,500 per m²; from about $450 per m² to supply and install double glazing into an existing aluminium frame
Canstar New aluminium or uPVC framed windows from around $550 for a 100cm x 60cm window; new timber frames upwards of $1,000 per m²
Superior Renovations (Auckland, updated Oct 2026) Retrofit for a typical 100m² home in good condition $18,000 to $28,000; full replacement of the same windows around $35,000
Flow press release (Scoop, Mar 2026) Full window replacement typically $800 to $1,500 per m² installed; $15,000 to $30,000+ for a standard three-bedroom home
RetroGLAZE (ArchiPro, Sep 2025) Retrofit typically prices 30% to 40% lower than full replacement

Superior Renovations, Flow and RetroGLAZE all sell glazing services, so read their numbers as industry estimates.

Double glazing cost per window

Per-window prices swing widely because size drives cost. Canstar found one company quoted $450 for a 1m² pane and $1,207 for a 2m² pane, so twice the area cost about 2.7 times as much. For a single heritage timber sash, Superior Renovations says replacing it with new aluminium double glazing runs roughly $1,200 to $2,500, and retrofitting a unit into the existing sash is cheaper again.

What pushes the price up

  • Larger glass areas. RetroGLAZE says the total amount of glass affects cost the most, with big sliders and floor-to-ceiling glass pushing budgets higher.
  • Glass type. Low-E (low-emissivity glass, which has a thin coating that reflects heat back into the room), laminated, acoustic and safety glass each add cost, according to RetroGLAZE.
  • Frame material. Canstar says top-quality timber-framed double glazing can reach $1,500 per m², while aluminium and uPVC usually cost less.
  • Access. Canstar notes second-storey windows that need scaffolding cost more.
  • Frame repairs. RetroGLAZE says frames that need repair during a retrofit lift the price.

Retrofit double glazing vs window replacement vs secondary glazing

The terms get used loosely, so ask every installer exactly what their price includes.

  • Retrofit double glazing. The old single pane comes out and a sealed double-glazed unit goes into your existing frame or sash. Superior Renovations calls it the right call for sound timber sashes and often the wrong one for old aluminium joinery. Canstar warns some existing frames cannot take the thickness of a double-glazed unit.
  • Full window replacement. EECA (the Energy Efficiency and Conservation Authority) describes this as removing the entire unit, frames included, and fitting new double-glazed windows. It says this suits frames at the end of their life.
  • Secondary glazing. EECA describes this as adding an extra pane to your existing window, creating an insulating gap while keeping the frame. It calls this the more cost-effective option, but says it relies on your existing windows being in good condition.

For a short-term or rental fix, EECA says shrink-wrap film kits are a low-cost DIY option that can, in some cases, cut heat loss almost as much as double glazing. The film will not stick to aluminium frames, and is designed to last one winter.

A BRANZ bulletin on timber windows notes that around a million NZ houses have timber-framed windows, most single glazed, and that these can suffer draughts and poor thermal performance. It covers both retrofitting units into timber sashes and replacing them with double-glazed uPVC or aluminium windows.

Energy and condensation benefits

EECA says up to 30% of a home's heating energy is lost through windows, making them the biggest source of heat loss in an otherwise well-insulated home, and double glazing can cut that share to 20% or less. It says double glazing helps reduce heat loss, condensation on the glass, and heating and cooling costs, and works best alongside good insulation.

EECA's pointers for good double glazing:

  • Argon gas between the panes can reduce window heat loss by 5% to 20% compared with air.
  • A 12mm to 16mm gap between panes gives the best insulation.
  • Plastic or stainless steel spacers insulate better than aluminium.
  • uPVC or timber frames lose less heat than aluminium and are less likely to attract condensation.

You do not need to do every window at once. EECA suggests starting with the rooms you use most or find hardest to heat. Good curtains help too: EECA estimates closing curtains before dark saves $80 to $90 a year. Find curtain and blind specialists on GetListed. Warmer rooms also make a heat pump work less hard; see our heat pump installation cost guide.

Usually not. Exemption 8 in Schedule 1 of the Building Act covers building work in connection with a window or exterior doorway in an existing dwelling or outbuilding of no more than two storeys, according to Building Performance (building.govt.nz). The exemption does not apply where:

  • the window being replaced failed the Building Code's durability rules. Building Performance says windows generally need to last at least 15 years, so replacing a rotted window under 15 years old needs consent, while replacing one over 15 years old does not.
  • the work modifies or affects a specified system, such as sprinklers or fire alarms.

All work must still meet the Building Code, and the altered building must comply to at least the same extent as before. Building Performance advises getting professional advice for work near potentially load-bearing walls. Widening an opening or changing structure is a different job, so talk to licensed builders about that. If the work needs a consent and affects the structure or weathertightness, it is restricted building work that a Licensed Building Practitioner must do or supervise; see our guide to Licensed Building Practitioners. BRANZ notes its helpline often gets questions about consent and weathertight detailing when windows are replaced in existing openings. If you are unsure, ask your council first.

Healthy Homes standards and double glazing for landlords

Double glazing is not required under the Healthy Homes standards. According to Tenancy Services, the insulation standard covers ceiling and underfloor insulation. Windows come into the other standards in two ways:

  • Ventilation: rental homes must have openable windows in the living room, dining room, kitchen and bedrooms. In each of these rooms, the openable windows, doors and skylights together must be at least 5% of the room's floor area. See our Healthy Homes standards guide.
  • Draught stopping: rentals must not have unreasonable gaps or holes in walls, ceilings, windows, skylights, floors and doors that cause noticeable draughts.

Double glazing can still make a rental warmer and drier, but it is an upgrade, not a compliance item. Find property managers who handle compliance.

Heritage and special character homes

Planning rules can apply even when a building consent is not needed. In May 2025, Newstalk ZB reported that Auckland Council ordered a Mt Eden villa owner in a special character area to seek resource consent or remove aluminium-framed double-glazed windows that had replaced the original timber sashes. Council's heritage manager said double-glazed panes can be installed into the historic wooden frames, and that this method does not require resource consent.

If your home is in a character or heritage area, check your council's district plan rules before ordering windows. An architect or designer can help with heritage work.

How to get double glazing quotes

EECA recommends professional advice and multiple quotes. Canstar advises making sure you are comparing like with like, meaning the same glass and frames. Ask each installer:

Check Why it matters
Retrofit, secondary glazing or replacement Prices are not comparable across methods
Glass spec (Low-E, argon, laminated) Affects warmth, noise and price
Safety glass where needed Superior Renovations notes some windows need safety glass under NZS 4223 (the New Zealand standard for glazing in buildings)
Frame repairs and making good Repairs and new trims add cost
Scaffolding for upper floors Canstar flags this as a cost
Consent or planning responsibility Who checks the exemption or district plan

Find local options on GetListed for builders in Auckland, Wellington or Christchurch, then ask each for a written, itemised quote.

Frequently asked questions

How much does retrofit double glazing cost in NZ?

Superior Renovations puts retrofit double glazing at $18,000 to $28,000 for a typical 100m² Auckland home in good condition. Canstar found prices from about $450 per m² to supply and install double glazing into an existing aluminium frame. RetroGLAZE says retrofit typically costs 30% to 40% less than full replacement.

What does window replacement cost in NZ?

A Flow press release puts full window replacement at $800 to $1,500 per m² installed, or $15,000 to $30,000+ for a standard three-bedroom home. Superior Renovations quotes around $35,000 to replace the windows in a typical 100m² Auckland home.

Is double glazing worth it in NZ?

EECA says up to 30% of a home's heating energy is lost through windows, and double glazing can cut that to 20% or less. It also reduces condensation. Whether it pays off depends on your heating costs and how well the rest of the house is insulated.

Is secondary glazing cheaper than double glazing?

EECA calls secondary glazing the more cost-effective option compared with replacing whole windows, but says it depends on your existing windows being in good condition. DIY shrink-wrap film kits are the cheapest option of all.

Usually not, for an existing house of up to two storeys. A consent is needed if a window under 15 years old has failed, or if the work affects a specified system such as sprinklers. Character areas can also have resource consent rules.

Sources

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