Owners · forum analysis
What New Zealand owners say about double glazing
Glaziers’ price guides tell you what a job should cost. Owners on Geekzone, New Zealand’s largest tech and home forum, wrote down what they were actually quoted, what the work was like and whether they would do it again.
What we found
Our calculations, data as of 23 October 2026
- Of the 43 threads we coded, 16 are about prices and quotes, 12 about condensation and ventilation, and 7 about frames and hardware. Few owners expect power savings to pay for the work; warmth, condensation and noise come up far more.
- Quotes for the same house vary widely. One 2019 owner had full replacement quotes from $20,000 to $35,000; a 2021 owner was quoted $35,000 for a retrofit, $56,000 for new double-glazed aluminium and about $72,000 for thermally broken.
- Owner-reported whole-house retrofits cluster around $10,000–25,000, matching 2026 glaziers’ ranges. Christchurch owners in 2024 reported about $10,000 for a three-bedroom house in aluminium and $22,000 for one with timber frames and low-E argon.
- The most common regret is cheap double glazing in plain aluminium frames: the glass stays dry but the frames run with water. Owners who chose uPVC or thermally broken frames rarely raise it.
What we read
We searched Geekzone for threads about double glazing, retrofit, secondary glazing and window condensation, kept the 43 that were about New Zealand homes, and coded each by its main topic. Together they hold 1,388 posts written between 2010 and 2026.
Prices owners were quoted
| Year | Where | Job | Price |
|---|---|---|---|
| 2015 | Auckland | Retrofit, 1980s aluminium, 42 glass units, 3 bedrooms | $11,300–14,144 |
| 2018 | Dunedin | Standard double glazing, aluminium, 10 windows and 2 sliders | $12,700 |
| 2019 | Whanganui | Retrofit, 1970s Lockwood, about 110 m² house, most rooms | $20,000 |
| 2019 | Dunedin | Retrofit into 110-year-old villa, 4 bay windows plus doors and 4 windows | about $25,000 |
| 2020 | – | Retrofit, 13 windows in 3 rooms, most with scaffolding | $13,000 |
| 2021 | – | Retrofit, low-E argon, into sound aluminium frames | $35,000 |
| 2023 | Auckland | Retrofit into timber frames, about 12 windows | about $15,000 |
| 2024 | Christchurch | Retrofit, 3-bedroom, aluminium frames | $10,000 |
| 2024 | Christchurch | Retrofit, 3-bedroom, timber frames, low-E argon | $22,000 |
| 2024 | Auckland | Thermally broken aluminium inserts, 23 windows, 1950s bungalow, laminated low-E argon | about $36,000 |
Our model prices a low-E retrofit of 25 m² of aluminium windows at $15,000, in the middle of what owners report. The outliers are explained by the job: timber frames, scaffolding, bay windows and large sliders all push the price up.
What owners say about the result
On warmth, owners treat double glazing as one part of a warmer house, alongside insulation and heating. One owner who weighed both had dry-blown insulation put into the walls first and described the difference as “dramatic and immediate”.
On noise, owners who chose laminated glass did so for quiet and security as much as for heat; one was offered it through the whole house for an extra $1,800 in 2019.
On power savings, the forum is blunt. “$43K pays for a LOT of power”, one owner replied to a quote for new joinery. Another worked out that paying for thermally broken frames would take “300 years to recoup” on heating savings alone. Our model agrees that, for a home heated part of the day, new windows take many decades to pay back.
What owners regret
- Plain aluminium frames. In a new house that had double glazing “done cheaply” in plain aluminium frames, the owner reported condensation every winter on the frames. Thermally broken, uPVC and timber frames avoid this; see window condensation.
- Waiting. Lead times are a recurring complaint: months for a measure and quote at busy times, and weeks of delay for glass.
- Not getting several quotes. The spread between quotes for the same house is often 50% or more. See comparing double glazing quotes.
What they would do again
Several owners did the work room by room, bedrooms and living room first, spreading the cost over years. Secondary glazing gets mixed reviews: one owner who chose stick-on panels after seeing replacement quotes of $20,000–35,000 liked the look, while another had “not heard anything good” about systems that leave the old glass in place.
This week: Palmerston North
Single glazing in an aluminium frame runs below the dew point about 2,430 hours a year in Palmerston North (H1 zone 3); clear double glazing cuts that to 350. A low-E retrofit of 25 m² saves $190 a year heated mornings and evenings with a heat pump, or $569 heated all day. Fastest payback here: DIY magnetic secondary glazing, 17 years.
Cheap fix. EECA estimates that closing curtains before dark saves $80–90 a year. Lined, full-length curtains with a pelmet work best. Read more