Retrofit Double Glazing Australia 2026 — Cost, Process & Payback
Retrofit double glazing swaps the glass without replacing the frame. In 2026 it costs $400–$700 per m² installed — 40–55% cheaper than a full window replacement, finished in 1–2 days.
Retrofit double glazing cost by house size (2026)
| Home size | Windows | Glass area | Retrofit cost | Vs full replace |
|---|---|---|---|---|
| Unit / small home | 5–7 | ~10 m² | $4,000–$7,000 | Save $3,500–$4,000 |
| 3-bed home | 8–12 | ~18 m² | $7,200–$12,500 | Save $6,300–$7,500 |
| 4-bed home | 14–18 | ~28 m² | $11,200–$19,500 | Save $9,800–$11,500 |
| Large / 2-storey | 20+ | ~40 m²+ | $16,000–$28,000+ | Save $14,000+ |
Note: Prices include IGU manufacture, removal of old glass, sash rebating (if needed), argon fill and installation.
How retrofit double glazing works
Site measure
Installer measures each opening and checks frame condition & rebate depth (needs 18–24 mm).
IGU manufactured
A sealed insulated glass unit (two panes + argon spacer) is made off-site — usually 2–3 weeks lead time.
Glass swap
Old glass is removed, the rebate is deepened if needed, and the new IGU is bedded in and sealed.
Finished in 1–2 days
No plaster damage, no re-painting, no dust storm inside the house. You can stay put during install.
Retrofit works well when…
- ✓ Timber frames in sound condition
- ✓ Thermally-broken aluminium frames
- ✓ You want to keep original heritage / character sashes
- ✓ Budget is the main constraint
- ✓ Frames have ≥18 mm rebate depth
Full replacement is better when…
- ✗ Frames are rotten, warped or draughty
- ✗ Standard single-track aluminium (poor U-value)
- ✗ You want the biggest possible NatHERS star lift
- ✗ Windows are already scheduled for renovation
- ✗ Rebate depth is under 18 mm
40–55% cheaper
Retrofit runs $400–$700/m² vs $750–$1,500/m² for full replacement — the biggest saving in the whole glazing upgrade market.
Fast install
Whole house done in 1–2 days. No demolition, no re-plastering, no re-painting — just glass in, glass out.
Heritage-friendly
Original sashes and frames stay put — ideal for Federation, Californian bungalow and Art Deco homes where a full replace kills the aesthetic.
Rebates that cover retrofit (2026)
- VIC — VEU program: $500–$2,000 discount at point of sale via accredited installers. Retrofit IGUs are eligible.
- NSW — Home Energy Saver: Up to $15,000 no-interest loan covering glazing (including retrofit) + insulation + HVAC.
- ACT — Sustainable Household Scheme: Zero-interest loan up to $15,000, retrofit eligible.
- TAS — Energy Saver Loan: Zero-interest up to $10,000 for eligible upgrades.
Get free retrofit double glazing quotes
Send us your postcode and rough window count — we'll match you with installers who retrofit IGUs into existing timber or aluminium frames. Free, no obligation.