Double glazing cost in NZ (2026)

Updated 11 November 2026. Prices are published NZ figures, linked to their source. Your tradie quotes after seeing the job.

Double glazing a whole three-bedroom house usually costs about $20,000 to $35,000 in Auckland, according to Superior Renovations’ 2026 guide. Per window, its Auckland prices start from $673 for a small window and $2,693 for a large one. Retrofitting glass into existing frames is typically priced 30% to 40% lower than replacing the windows (RetroGLAZE, 2025), but only works if your frames are in good condition.

Almost every NZ figure for double glazing comes from companies that sell it. The government and research sources below cover the benefits and the rules, not the prices. Use the numbers as a guide and get written quotes for your own windows.

The quick answer

Superior Renovations is an Auckland renovation company, and its page is the only one here with dollar prices, so these are Auckland vendor figures, not a national average. The page says thermally broken aluminium frames cost roughly 25% to 40% more per opening than standard aluminium, uPVC usually falls between the two, and timber is typically the premium option.

The two vendors do not line up neatly. Superior Renovations says its whole-house retrofit figure is also around $20,000 to $35,000, while its per-window page says retrofit is under the full-replacement rates. RetroGLAZE says 30% to 40% lower. Ask for both a replacement price and a retrofit price on the same windows.

What changes the price

Window size and type. Superior Renovations prices by opening: small, medium, large, bi-fold, sliding door and skylight. It says bi-folds are priced per leaf, not per opening, and that sliding doors are the costly item at from $6,831 each.

Frame material. Consumer NZ (October 2021) says thermally broken aluminium frames slow heat transfer and cut condensation, PVC is excellent at keeping heat in, and timber is the most expensive frame material and needs more maintenance. EECA says uPVC or wood frames lose less heat than aluminium.

Glass options. EECA says an inert gas such as argon can reduce window heat loss by 5% to 20%, and that a low-E coating can reduce it by up to 30% compared with regular glazing. Consumer NZ says these extras can quickly add cost if fitted throughout the house, and suggests using them in the rooms you use most.

Retrofit or replace. EECA lists three main retrofit routes: secondary glazing (an extra pane added to your existing window), retrofitting insulating glass units into the existing frame, or replacement windows. It says the first two need existing windows in good condition, and replacement suits frames at the end of their life.

Rot behind the frame. Consumer NZ says if the frames have rotted, the job stops while you find a builder to repair them. That repair is not in a window quote.

Finishing. Consumer NZ says you may need new architraves inside and painting inside and out, and the installer may include these or you can do them.

What it saves

EECA says up to 40% 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 reduce this to 25% or less. EECA adds that double glazing reduces condensation and heating and cooling costs, and works best alongside good home insulation.

BRANZ makes a similar point: windows are about 8% to 10% of the thermal envelope’s area but can be responsible for up to 40% of heat losses. It says many double-glazed windows last an average of 20 to 30 years.

An older marketplace article (Builderscrack, published 2015 and last updated 2021) gives different figures: 46% of interior heat lost through single glazing, 33% with double glazing and 20% with high-performance double glazing in thermal frames. These are not directly comparable with EECA’s, which measures a share of heating energy. It is a tradie marketplace, so give it less weight than EECA or BRANZ.

BRANZ also warns that the frame matters as much as the glass. A double-glazed aluminium window is not always better than a single-glazed timber one, because aluminium conducts heat and can cancel most of the benefit, especially in small windows. It recommends asking for a WEERS rating, the window energy rating system, to see the true R-value of each window.

None of these sources gives a payback period for the cost, so do not assume the savings will cover the price quickly. EECA suggests starting with the rooms you use most, and describes film kits and curtains as cheaper first steps.

A worked example

Using the figures above, take Superior Renovations’ own worked example for an Auckland house: eight medium windows, two large, two small and one sliding door, at its “from” prices.

• 8 medium windows at $1,683 = $13,464
• 2 large windows at $2,693 = $5,386
• 2 small windows at $673 = $1,346
• 1 sliding door at $6,831

The total is $27,027 at the lowest listed prices. Superior Renovations says the same example lands at roughly $27,000 to $30,000.

If you then ask for a retrofit quote and RetroGLAZE’s 30% to 40% lower figure held, the same house would come to about $16,200 to $18,900. That is only an illustration: it needs your frames to be in good condition, and the vendor gave no dollar prices to back it up.

Rules, licences and consents

Building consent. The Ministry of Business, Innovation and Employment (MBIE) says a building consent is usually not required for building work on a window or exterior doorway in an existing dwelling or outbuilding of no more than 2 storeys. The two exceptions are replacing a window or doorway that has failed to meet the Building Code’s durability requirements, and work that modifies or affects a specified system such as sprinklers or fire alarms (MBIE exemption 8).

The 15-year rule. MBIE says windows and doors in an external wall are required to last at least 15 years. If a window older than 15 years has rotted out, replacing it needs no consent. If a window installed within the last 15 years has failed, replacing it does need one. MBIE also says to get professional advice from a Chartered Professional Engineer, registered architect, building consultant or registered building surveyor if the work is close to or involves potentially load-bearing walls. Its examples show that a wider opening needs a new lintel.

Building Code still applies. MBIE says all new building work must comply with the Building Code even when no consent is needed. BRANZ (last updated 1 December 2023) says that if the glazing area is not increased, the replacement window’s R-value under Building Code clause H1 must be at least the same as or better than the original. Because timber frames insulate better than aluminium, replacing timber with aluminium most likely needs double-glazed units to match. EECA says most new houses and additions now require double glazing, and Consumer NZ says any new windows need to be double glazed to meet Building Code requirements. If your replacement is a pool barrier window, MBIE says the Building Act pool rules still apply.

Flashings and weathertightness. BRANZ says that when you replace a window, the framing and the underlay behind it should be checked for soundness, and gives flashing tape, sill tray and head flashing details. Consumer NZ says it pays to have new flashings installed at the same time.

Restricted building work. MBIE’s page on restricted building work (updated 15 January 2026) lists windows, doors and skylights as part of a home’s weathertightness. It says work is only restricted building work when it requires a building consent, and lists “installation of most windows” as work that does not. If your job does need a consent, a Licensed Building Practitioner must do or supervise the weathertightness work. See our guide to checking a builder’s LBP licence.

Contracts and your rights. Building.govt.nz says you must have a written contract for residential building work costing $30,000 or more including GST. You also get a 12-month defect repair period, and implied warranties apply for 10 years (building.govt.nz, protection for homeowners).

Questions to ask before you say yes

• Is the price per window or for the whole job, and does it include GST?
• Is this a replacement, a retrofit into my existing frames or secondary glazing?
• What frame material, glass type, spacer and gas fill am I getting?
• What is the WEERS rating or R-value of each window?
• Does the price include removal, new flashings, architraves and painting?
• Who checks my frames for rot, and what happens if they are rotted?
• Who decides whether a building consent is needed, and who applies for it?
• What warranty covers the glass seals and the installation?

How GoodTradie helps

GoodTradie is free for homeowners. We do not list glazing specialists yet, so we cannot find you a glazier. This guide is here to help you judge a quote you have already been given, using published NZ figures. The box at the top of the page is for the plumbing, electrical and other trades we do cover. That price comparison is a guide, not a guarantee of the best price. If you need one of those trades for the same renovation, type the job into the box at the top of the page.

Sources

• Superior Renovations, double glazing cost calculator NZ, published 7 September 2026, updated 4 November 2026
• RetroGLAZE on ArchiPro, the cost of double glazing, 30 September 2025
• EECA, window insulation (page undated)
• BRANZ, Time to change the windows, last updated 1 October 2021
• BRANZ, Replacing windows in existing openings, last updated 1 December 2023
• Consumer NZ, Replacing your windows, October 2021
• MBIE, 3.1 Windows and exterior doorways in existing dwellings and outbuildings (page undated)
• MBIE, restricted building work, updated 15 January 2026
• Building.govt.nz, protection for homeowners (page undated)
• Builderscrack, double glazing article, published 18 February 2015, last updated 21 January 2021