Alternatives to Double Glazing: A Practical Guide for Australian Homes (2026)
Full double glazing isn't always the right call. Here are the six main alternatives — secondary glazing, DIY kits, window inserts, films, panels and thermal curtains — with what each actually does, where each makes sense, and where it doesn't.
The main alternatives to full double glazing are secondary glazing (sometimes sold as secondary glazed windows), DIY double glazing kits (acrylic panels with magnetic strips), professional magnetic window inserts, polycarbonate or acrylic panels used as a glass alternative, energy saving window film, and heavy thermal curtains. Of these, secondary glazing delivers the closest performance to a true double pane window — particularly for noise and condensation. The rest sit somewhere on a scale between "useful for a single problem room" and "marginal".
Three things to think about first
- How long you'll stay in the home. Short-term or rental? An alternative often makes sense. 10+ years? Replacement usually pays back faster.
- Whether the existing frames are sound. If timber frames are rotted or aluminium frames are warped, no alternative on top of them will perform well.
- What problem you're solving. Noise, condensation, heat gain, heat loss, or all four — each alternative is better at some and weaker at others.
What's in this guide
- All 6 alternatives compared at a glance
- Secondary glazing — the closest alternative to true double glazing
- DIY double glazing kits (Bunnings and similar)
- Magnetic window inserts (Magnetite, Soundblock Solutions)
- Acrylic and polycarbonate panels
- Energy saving window film
- Heavy thermal curtains
- When full double glazing replacement makes more sense
- Frequently asked questions
All 6 alternatives compared at a glance #
Before going deep on each option, here's how they compare. If you're shopping for the most affordable double glazing solution, this side-by-side of the main double glazing alternatives is the fastest way to see how much each option realistically costs and what you get for it. Pricing is broad — actual figures depend on window size, opening style, glass specification, brand, and whether you fit yourself or pay a professional. The full uPVC double glazing column reflects our installed 2026 Melbourne pricing as published on our double glazed windows cost Melbourne page (useful if you're after a double glazing cost calculator-style breakdown).
| Option | Indicative cost | Thermal gain | Noise reduction | Typical lifespan |
|---|---|---|---|---|
| Secondary glazing (professional) | Varies by window — typically a meaningful saving vs full replacement | Good | Rw 25–32 dB over an old frame | 10–15+ yrs (limited by host window) |
| DIY kits (specialist online suppliers) | Materials around $150–$300 per window (small to medium sizes) | Modest | Minimal | 3–5 yrs (acrylic clouds and scratches) |
| Magnetic inserts (Magnetite, Soundblock Solutions) | Indicatively $380–$420 per m² supply-only (brand reports) | Moderate | Moderate | 5–10 yrs |
| Polycarbonate / acrylic panels | Varies | Moderate | Low | 5–10 yrs |
| Energy saving window film | From around $30–$40 per m² (Bunnings adhesive film) | Solar gain reduction only | None | 5–15 yrs |
| Heavy thermal curtains | Ready-made stock from Bunnings, Spotlight, IKEA, Kmart | Slight (only when drawn) | Slight | 10+ yrs |
| Full uPVC double glazing | $2,300–$3,500+ per window installed | Best | Rw 34+ dB | 30+ yrs |
For a deeper head-to-head on the most popular alternative, see our guide on secondary glazing vs double glazing in Melbourne.
1. Secondary glazing — the closest alternative to true double glazing #
Secondary glazing — also called secondary glazed windows or simply double pane retrofitting — is a separate pane of glass (or acrylic) installed on the inside of an existing window, creating an air gap between the two layers. The original window stays in place. Of all the alternatives on this page, it's the one that delivers performance closest to a factory-made double glazed unit — particularly for noise reduction, condensation control, and U-value improvement.
Secondary glazing is also the most common path for heritage-overlay homes across inner-Melbourne suburbs like Carlton, Fitzroy and Port Melbourne, where window replacement may not be permitted but interior modifications usually are. It applies equally well to sash windows, casement windows, fixed picture windows, and french doors.
Where secondary glazing works well
- Real, measurable noise reduction (typically Rw 25–32 dB over a single-glazed frame)
- Noticeable comfort improvement — warmer rooms in winter, less radiated heat in summer, and a much quieter room overall
- Cheaper than full window replacement — often substantially
- Approved for most heritage-overlay properties
- Original window kept in place — no frame disturbance
- Reversible — can be removed at end of lease or sale
- Reduces condensation in most situations
- Works across window types: sash, casement, awning, fixed, french doors
Where it falls short
- Performance ceiling is set by the underlying window's air leakage
- Adds a second pane to clean
- If the original timber frame is rotted or rusted, that needs repair first
- Lifespan is limited by the host window underneath
- If you stay 20+ years, total spend on secondary glazing plus eventual window replacement can end up higher than just replacing the windows once at the start
Best fit for: heritage homes, rentals (with landlord permission), and owners staying 5–10 years. For owner-occupiers planning to stay 10+ years, the maths usually starts favouring full replacement.
2. DIY double glazing kits #
"DIY double glazing" is not quite accurate as a label — a true factory-sealed insulated glass unit can't be made on-site. What's sold as DIY double glazing is closer to self-installed secondary glazing: a clear acrylic or polycarbonate sheet that you fit to the inside of an existing window using a magnetic, clip-in, or adhesive strip frame.
Bunnings doesn't actually stock complete DIY double glazing kits — its window range is mostly finished aluminium or timber units. For a proper DIY kit you'll need a specialist Australian supplier such as AMF Magnetics (which sells magnetic tape strips for DIY double glazing), ecoMaster / ecoGlaze (ready-to-go magnetic kits), or eBay sellers stocking acrylic sheets cut to size. Materials are typically a few hundred dollars per window for small to medium openings, depending on whether you buy a complete kit or just the magnetic strips and source your own acrylic. These kits are a genuine option for a single problem room — a cold child's bedroom, a noisy study — but it pays to be realistic about what they deliver.
What they're good for
- Lowest entry cost of any glazing option
- No installer required — a weekend job
- Removable for rentals
- Better than nothing for a single problem room
Realistic limitations
- Acrylic typically yellows and scratches over 3–5 years
- Adhesive seals can degrade — the air gap stops being airtight over time
- Thermal benefit is modest compared to engineered systems
- Noise reduction is limited (effective acoustic glazing needs mass and a sealed cavity)
- Visible edge framing affects how the window looks
3. Magnetic window inserts (Magnetite, Soundblock Solutions) #
Professional magnetic window inserts — sometimes referred to as double glazed window inserts even though technically they're sealed secondary glazing — sit between a DIY kit and full secondary glazing. They use a steel-backed frame fitted to the window reveal and a custom-cut acrylic or glass panel held in place by a magnetic seal. Brands operating in Australia include Magnetite and Soundblock Solutions, with Magnetite being the most widely retrofitted across Melbourne.
Published indicative pricing for Magnetite from user reports and forum discussions sits around $380–$420 per square metre supply-only, with installed pricing higher depending on window size, glass thickness, and access. Across the broader secondary glazing market in Australia, professionally installed systems generally run between $300 and $650 per square metre. Per-window cost is broadly comparable to the lower end of professional secondary glazing.
Performance is genuinely better than a generic DIY kit because the magnetic seal creates a properly closed cavity, and the panel is custom-cut rather than trimmed by you. They're also cleanly removable — useful for rentals and for heritage properties where you don't want any permanent modification.
Strengths
- Professional installation with custom-cut panels
- Useful noise reduction for traffic and conversational noise
- Cleanly removable — no permanent change to window or frame
- Faster install than full secondary glazing
- Available in both acrylic and glass panels
What to consider
- Acrylic panels still scratch and cloud over time
- Magnetic seal can lose tension after 5–10 years and need re-tensioning
- Optical clarity slightly below proper glass
- Over a 20-year horizon, full uPVC double glazing replacement often works out cheaper per year
4. Acrylic and polycarbonate panels (a cheap glass alternative) #
Stand-alone acrylic or polycarbonate sheets fitted into a timber or aluminium sub-frame and screwed to the window reveal. As a cheap alternative to glass windows in workshops, sheds, garage conversions and budget rentals, they're a practical option. They sit somewhere between the DIY kits above and professional magnetic inserts, depending on how well they're fitted.
Polycarbonate is usually the better glass alternative for Australian conditions because it yellows more slowly than acrylic and is more impact-resistant. Both are much lighter than glass, which can be an advantage on upper-floor windows or older timber frames that wouldn't comfortably take the weight of a true double glazed unit.
Plastic isn't glass. All polymer-based panels degrade in Australian UV faster than they would in milder climates. Plan for replacement at the 5–10 year mark and factor that into any total-cost comparison with full double glazing.
5. Energy saving window film #
A thin adhesive film applied directly to the inside of existing glass. It reduces solar heat gain in summer (especially useful on west-facing windows) and reflects a small amount of long-wave radiated heat back into the room in winter. DIY rolls are available from Bunnings — for example the Pillar 1.2 x 2.4 m crystal clear adhesive window film — at around $30–$40 per square metre. Professionally installed brands include 3M, Solar Gard and Llumar.
Energy saving window film doesn't add a second pane, so it can't reduce noise and can't replicate the insulating air gap of true double glazing. It's a solar control product first, and a very modest thermal product second. For an afternoon-sun problem in a west-facing living room it can be genuinely useful. For a cold bedroom in winter it won't move the needle much.
What it does well
- One of the lowest-cost glazing upgrades available
- Meaningfully reduces summer solar heat gain
- UV protection (slows fading of furnishings and timber floors)
- Doesn't change how the window looks from the street
What it can't do
- Won't reduce noise
- Minimal winter thermal benefit
- Doesn't fix condensation
- Some films can void the original window's manufacturer warranty
6. Heavy thermal curtains and pelmet lining #
Often overlooked, but a properly lined thermal curtain with a sealed pelmet at the top can meaningfully reduce overnight heat loss when closed. The lining traps a still-air layer between fabric and glass. Ready-made blockout and thermal-lined curtains are stocked widely across Bunnings, Spotlight, IKEA and Kmart at consumer-friendly prices — the bigger factor in real-world performance is the pelmet (which stops warm air convecting up and out at the top) rather than the fabric brand itself. They're reversible, and they double as decor.
The obvious limitation: they only work when drawn. That makes them useful as a complement to other improvements (especially in bedrooms at night) rather than a real substitute on living-area windows where you want daylight.
When full double glazing replacement makes more sense #
Alternatives to double glazing have a real place. There's also a point where stacking workarounds costs more than just doing the job once. Full uPVC double glazing replacement is generally the better path when one or more of the following applies:
- The existing frames are deteriorated. Rotted timber, warped aluminium, rusted hardware — no second pane on the inside fixes a failing window underneath it.
- You're planning to stay 10+ years. Full uPVC double glazing has a 30+ year lifespan with minimal maintenance. Over that horizon, total cost of ownership often comes out lower than installing and replacing cheaper alternatives twice.
- The noise problem is heavy traffic, trains, or aircraft. Heavier sound sources typically need the mass and sealed assembly of a replacement window with laminated double glazing to reach Rw 34+ dB and higher. Secondary glazing helps significantly (Rw 25–32 dB over an old frame), but for the heaviest sources, replacement performs better. Our antinoise window range covers what's possible at the upper end.
- You're doing a renovation or extension anyway. The marginal extra cost of full double glazing when walls are already open is usually small relative to the long-term performance benefit.
For Melbourne-specific cost guidance on the full replacement route, see double glazed windows cost Melbourne or window replacement Melbourne. To explore the full range of uPVC double glazed window styles available (sliding, tilt & turn, casement, awning, fixed and more), see our uPVC windows hub. Pricing is broadly similar in Sydney, Adelaide, Perth and across most Australian capital cities, though installer rates and access conditions vary.
Not sure which option fits your home? Windows Republic offers a free measure and quote across Melbourne. We can walk you through the side-by-side cost and expected performance of secondary glazing vs full uPVC double glazing for your specific windows — no obligation.
Frequently asked questions #
What is the cheapest alternative to double glazed windows?
The cheapest options are energy saving window film (around $30–$40 per square metre from Bunnings) and ready-made heavy thermal curtains — but both are limited. Film only addresses solar heat gain; curtains only work when drawn. The cheapest alternative that meaningfully insulates is a self-installed DIY double glazing kit (acrylic with magnetic strips), typically a few hundred dollars per window in materials from specialist suppliers like AMF Magnetics or ecoMaster. For closer-to-real performance, professional secondary glazing or branded magnetic inserts (Magnetite, Soundblock Solutions) are the lowest-cost solutions.
Does secondary glazing work as well as double glazing?
Secondary glazing delivers a meaningful share of the thermal and acoustic performance of a true double glazed window, but it doesn't fully match it. Replacement uPVC double glazing typically achieves Rw 34+ dB for noise reduction; secondary glazing over an existing single-glazed frame typically achieves Rw 25–32 dB. The gap exists because the original window's air leakage and frame thermal bridging cap the overall performance. For heritage-overlay homes where replacement isn't permitted, secondary glazing is usually the strongest practical option.
Can you double glaze existing windows yourself?
Not in the strict sense — a true factory-sealed double glazed unit requires manufacturing equipment and a sealed environment, so it can't be assembled on-site. What's marketed as "DIY double glazing" is really self-installed secondary glazing: a second acrylic or polycarbonate panel fitted to the inside of an existing window with magnetic, clip-in or adhesive strips. Bunnings doesn't stock complete kits, so most Australian DIYers buy from specialist suppliers like AMF Magnetics (magnetic tape strips), ecoMaster/ecoGlaze (full ready-to-go kits), or eBay listings with acrylic cut to size. Material cost is typically a few hundred dollars per window for small to medium openings. The benefit is modest and the lifespan is shorter than professional secondary glazing or full replacement.
What is the difference between secondary glazing and double glazing?
Double glazing is a factory-sealed unit of two glass panes with an argon or air-filled cavity between them, fitted as a complete new window. Secondary glazing is a separate pane (or full sash) added to the interior side of an existing window, with a non-sealed air gap. Double glazing performs better because the cavity is permanently sealed and the frame is purpose-built. Secondary glazing is significantly cheaper, reversible, and works in heritage homes where replacement isn't allowed. Full breakdown: secondary glazing vs double glazing Melbourne.
Is secondary glazing cheaper than double glazing?
Yes, secondary glazing is typically cheaper than full double glazing replacement on a per-window basis. Full uPVC double glazing replacement in Australia is currently $2,300–$3,500+ per window installed. Professional secondary glazing is usually meaningfully less. The trade-off is lower performance (especially in the long run) and shorter lifespan, since the underlying single-glazed window remains in place. For owner-occupiers staying 10+ years, the upfront saving from secondary glazing often narrows once you factor in long-term energy bills and replacement of any cheaper system that doesn't last 30+ years.
Do magnetic window inserts really work?
Yes — professional magnetic inserts from brands like Magnetite and Soundblock Solutions are an effective middle ground between a cheap DIY kit and full secondary glazing. The magnetic seal creates a properly closed cavity, and the panel is custom-cut to your window. They reduce traffic and conversational noise noticeably, and provide moderate thermal improvement. The main limitations are acrylic panel clouding over 5–10 years and the need to occasionally re-tension the seal.
Are alternatives to double glazing suitable for heritage homes?
Yes — secondary glazing and magnetic window inserts are both popular for heritage homes because they're installed on the interior side and don't modify the original window or the building facade. Both are typically permitted under Victorian heritage overlay rules, including for sash windows and french doors. Window film is also non-invasive but offers more limited performance. Replacing original timber sash windows with uPVC frames typically requires a planning permit in heritage zones — your council is the final authority.
Will secondary glazing stop condensation?
In most cases secondary glazing significantly reduces condensation, because the inner pane stays warmer than the original single-glazed pane and therefore doesn't drop below the dew point as easily. It doesn't always eliminate condensation entirely — outcomes also depend on indoor humidity, ventilation, and whether the cavity between the two panes is reasonably sealed. For homes with persistent condensation issues, full double glazing with a warm-edge spacer typically performs better.
What's the best alternative for noise reduction?
Professional secondary glazing with a wider air gap (50–100 mm) is generally the best alternative for noise reduction, often outperforming a standard sealed double glazed unit on low-frequency sources like heavy traffic and trains, because the larger cavity dampens those frequencies more effectively. Magnetic window inserts are the next-best option. DIY kits, window film and curtains provide limited acoustic benefit. For the heaviest noise sources, replacement windows with laminated double glazing in a sealed uPVC frame typically achieve the strongest result.
Is double glazing worth it compared to alternatives?
Full double glazing tends to be worth the higher upfront cost when you plan to stay in the home 10+ years, when the existing frames are deteriorating, or when you're already doing renovation work. Its 30+ year lifespan, stronger thermal and acoustic performance, and minimal maintenance mean total cost of ownership over two decades often comes out lower than the cost of installing and replacing cheaper alternatives. For shorter-term fixes, single problem rooms, rentals or heritage homes where replacement isn't permitted, an alternative makes more sense.
Can you add secondary glazing to french doors and sash windows?
Yes — secondary glazing is one of the more flexible window upgrades because it sits on the interior side of the existing window. It can be fitted to most window and door types, including double hung sash windows, casement windows, awnings, fixed picture windows, and french doors. Configuration (sliding, hinged or fixed secondary sash) depends on whether you still need the original window to open. For french doors especially, hinged secondary panels are typical so the doors remain functional.
Considering full uPVC double glazing?
If you'd like a side-by-side view of what secondary glazing vs full uPVC replacement would cost for your specific windows, we can put together a free measure and quote across Melbourne.
