Invercargill sits in one of New Zealand's coldest climate zones, and older single-glazed homes across Southland lose most of their heat straight through the windows. Whether you're after full frame replacement or retrofit double glazing into your existing joinery, we've verified the local installers who actually do this work - not just the ones who rank well in Google.
This page highlights the Top 5 double glazing installers in Invercargill, based on independent research into reputation, accreditation, service quality and overall reliability.
The top 5 double glazing installers in Invercargill are 1. Invercargill Glass & Mirror (Edminstin Windows & Doors Ltd), 2. RetroFit Double Glazing - Southland, 3. Deep South Glass, 4. Nebulite Southland, 5. Excel Glass & Joinery Services Southland. Below we explain why each made the list, compare them at a glance, and share how to choose.
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A verified WGANZ member with a live listing on the association's own site, this third-generation, 100% Southland-owned family business has run from 94 Bill Richardson Drive since 1991. It carries a 5-star Google rating across 65 reviews, a strong independent signal for a business this size.
RetroFit is a subsidiary of NZX-listed Metro Performance Glass, New Zealand's largest retrofit double glazing specialist with close to 40 years in the market. The Invercargill branch operates from 99 Clyde Street West as Metro Direct Southland, offering both aluminium and timber retrofit with factory-sealed units and a 10-year manufacturer warranty.
A registered NZ company (NZBN 9429047908239) operating from 24 Bond Street, founded by Dan Fisher and Phil Williams with a combined 50+ years in the trade. Deep South Glass lists retrofit double glazing as a core service and holds SiteWise Gold 2025 accreditation, an independent health and safety pre-qualification.
A confirmed WGANZ member (independently verified on wganz.org.nz) trading from a showroom at 61 Tweed Street since 1993, locally owned and operated by Daniel Rosel. It carries a 5.0-star Google rating across multiple independent directory citations.
A genuine local operator at 49 Benmore Street offering retrofit double glazing alongside kitchen, bathroom and laundry joinery, backed by a qualified joiner on the team. Reviews are consistently positive, though the independently verifiable review volume is smaller than the other listed operators.
A quick comparison of our Top 5 picks. Select up to 3 businesses above to compare their strengths side by side.
| Double Glazing Installer | Best for |
|---|---|
| Invercargill Glass & Mirror (Edminstin Windows & Doors Ltd) | Homeowners wanting a long-established, association-verified local glazier |
| RetroFit Double Glazing - Southland | Homeowners wanting a nationally backed brand with manufacturer warranty |
| Deep South Glass | Homeowners wanting a registered local company with H&S accreditation |
| Nebulite Southland | Homeowners who want to see products in a showroom before buying |
| Excel Glass & Joinery Services Southland | Homeowners wanting retrofit glazing combined with joinery work in one job |
Independent, editorial, and reviewed regularly.
TopChoice rankings are editorially curated by our New Zealand team and reviewed periodically. We don't host our own reviews. Our shortlists draw on public reputation signals from Google and other platforms, alongside our own research into each double glazing installer. We weigh up a combination of:
We don't accept payment in exchange for a place in the Top 5. Featured placements are separate and always clearly labelled. Rankings may change over time as businesses evolve.
Since May 2023, NZ Building Code Clause H1 has required a minimum window and door R-value of R0.46 in Invercargill's climate zone - almost double the old R0.37 standard. Even so, glazing remains the weakest thermal element in most Southland homes compared to walls and roof insulation, which is exactly why double glazing delivers such a noticeable difference in a cold climate like this one. Any installation should also meet NZS 4223, the national glazing standard - Part 1 covers glass selection and design, while Part 3 sets human-impact safety requirements for glazing within 2000mm of floor level. Checking a company's WGANZ (Window & Glass Association New Zealand) membership is one of the few genuinely independent ways to confirm an installer is held to industry standards, rather than relying on marketing claims alone.
Worth knowing before you get quotes: there's no EECA grant for double glazing. Unlike insulation and heat pumps, which are funded through the Warmer Kiwi Homes scheme, windows and glazing are explicitly excluded - so budget for the full cost. You'll also need to decide between two genuinely different approaches: full frame replacement installs entirely new double-glazed aluminium or timber joinery, while retrofit or secondary glazing fits a double-glazed unit into your existing frames, which is usually faster and cheaper. Established retrofit systems like RetroFit Double Glazing (a Metro Performance Glass subsidiary) and Magnetite secondary glazing are both legitimate, proven options if a local installer offers them.
Cost depends heavily on whether you choose full frame replacement or retrofit glazing into existing frames, plus the number and size of windows. Retrofit is generally the cheaper option since it reuses your existing joinery. Get a free measure and quote from at least two local installers to compare, since pricing varies by glass spec (Low-E, thickness) and frame material.
No. Unlike insulation and heat pump installations, which can be funded through EECA's Warmer Kiwi Homes scheme, double glazing and window replacement are explicitly excluded from that programme. There is currently no national government grant specifically for double glazing in New Zealand.
Full frame replacement installs entirely new double-glazed aluminium or timber window and door joinery, replacing the old frames completely. Retrofit (or secondary glazing) fits a new double-glazed unit into your existing frames without replacing them, which is typically faster, less disruptive and cheaper, though full replacement can offer better overall performance and is worth considering if your existing frames are worn or dated.
Retrofit double glazing into existing frames is usually completed within a day or two for an average home, since the existing joinery stays in place. Full frame replacement takes longer, often several days to a couple of weeks depending on the number of windows and doors and whether any structural work is needed.
Yes. Southland's climate means windows are typically the weakest thermal point in an older home, even after wall and roof insulation upgrades. Since the 2023 update to Building Code Clause H1, new windows must meet a minimum R0.46, well above older single-glazed performance, and retrofit double glazing lets you upgrade older joinery without a full renovation.
Editorial disclosure: TopChoice is an independent editorial platform. Some pages may include clearly labelled featured placements for additional visibility. Featured placements do not influence rankings within our Top 5 lists.
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