The questions we get asked most about retrofit double glazing and heritage timber windows.
What is double glazing retrofit?
Double glazing retrofit replaces the single pane of glass in your existing window frame with an insulated glass unit (IGU) — two panes of glass with a sealed, gas-filled gap between them. Unlike full window replacement, retrofitting keeps your original timber frames intact, which makes it ideal for older and heritage homes where the frames themselves have character worth preserving.
How much does double glazing retrofit cost in Melbourne?
It depends on the window type, pane size and frame condition. As a guide: a single fixed, casement or awning pane typically runs $360–$625 installed (ex GST), while a full double-hung sash window — both sashes, two panes, cords and rebalancing included — runs $1,200–$1,490. Smaller jobs (one or two panes) carry a slightly higher cost per pane, since a standard installation visit (travel, setup and clean-up) applies regardless of job size. The best way to get an accurate number is our
instant estimator or a free on-site quote.
Will double glazing retrofit damage or change the look of my heritage windows?
No — that's the main advantage of retrofitting over replacement. The original timber frame, sash and external appearance stay exactly as they are. Only the glass itself is upgraded, so the window keeps its heritage character while gaining modern thermal and acoustic performance.
Do I need council or heritage overlay approval to retrofit double glazing?
In most cases, no — retrofitting doesn't alter the external appearance of the window or the building. That said, if your property is in a heritage overlay it's worth checking with your local council first. We can advise based on similar jobs completed across Banyule, Heidelberg, Eaglemont and Ivanhoe.
How long does a double glazing retrofit job take?
A fixed pane typically takes around 2 hours to retrofit, casement and awning sashes closer to 3 hours due to the extra hardware involved, and a full double-hung sash window around 8 hours given both sashes need to come out, be reglazed and rebalanced. Most residential jobs (10–15 windows) are completed within a day or two.
Does double glazing actually reduce noise and heat loss?
Yes. The sealed, argon-filled gap between the two panes significantly reduces heat transfer — our standard Optitherm® Low-E spec brings the U-value down to around 1.4, versus roughly 5.8 for the single glass it replaces. It also dampens external noise, which is particularly useful for homes near busy roads or older weatherboard and timber-framed houses with single-glazed originals.
What glass specification do you use?
For most retrofits we use a Low-E coated pane paired with a clear toughened pane and an aluminium spacer bar — Optitherm®, which balances thermal performance with cost. For heritage frames needing extra acoustic performance, a laminated glass option is available. We'll recommend the right spec for your specific windows during the quote.
Can I retrofit just some of my windows, or does it have to be the whole house?
You can retrofit as few or as many windows as you like. Many clients start with the rooms that matter most — bedrooms for noise, living areas for heat — and expand later.
What areas does Window Lust service?
We're based in Banyule and service Melbourne's northern and inner-north suburbs, including Heidelberg, Eaglemont, Ivanhoe, Ivanhoe East, Northcote, Fitzroy, Brunswick and Kew, with heritage timber window restoration as a specialty. We'll travel further for the right job — give us a call if you're not sure.
Is double glazing retrofit a DIY job?
It's not recommended. Removing original sashes without damaging the timber, correctly sizing and sealing the new IGU, and maintaining weatherproofing all require experience working with older frames. We bring 18 years of home maintenance and glazing background specifically suited to this kind of work.
