DIY or pay a glazier? The honest version.
We are a glazing company telling you that DIY secondary glazing is a legitimate answer for some jobs. It is. It is also completely the wrong answer for others, and the line between them is sharper than most people expect. Here is where it falls, what each path really costs in 2026, and the one job you should never attempt on a Saturday.
One cold room, one weekend, one magnetic kit.
If you have a single freezing bedroom on the south side of an Endeavour Hills or Narre Warren house, and the existing timber reveal is straight and sound, a magnetic acrylic secondary panel is a genuinely good buy. You cut a sheet of 4mm acrylic to size, run a steel or magnetic tape frame around the reveal, and clip the panel on. It seals a still-air cavity in front of the existing glass, which is exactly the physics that makes double glazing work in the first place. Expect roughly 40-50 percent less heat loss through that opening and a few decibels off road noise, for about $90-$160 per square metre in materials.
That is not a compromise product. Secondary glazing is what conservation architects specify on listed buildings in Britain precisely because it works and it is reversible. The DIY version and our professional version use the same principle. The differences are the panel material, the seal quality and how long it stays looking good.
The four honest DIY use cases.
- One or two problem rooms where the rest of the house is fine and you are not chasing a whole-of-house energy outcome.
- A rental you are living in and cannot legally modify, where a fully reversible magnetic panel that comes off at the end of the lease is the only option available.
- Testing before committing - fit a kit to the worst room for $200 and see whether the improvement is worth $20,000 across the house. We have had customers do exactly this and then call us. That is a sensible way to spend money.
- Sheds, studios and rumpus conversions where the standard is comfort, not compliance or resale.
Where it quietly falls apart.
Acrylic is not glass. It scratches if you look at it wrong, it needs washing with a microfibre and nothing else, and after 8-12 years of Melbourne UV on a north or west elevation it goes slightly yellow and hazy. It also flexes, which means the magnet seal at the centre of a large panel lets go before the corners do. Above about 1.5 square metres, DIY acrylic starts to look like DIY acrylic.
The bigger problem is the frame you are sticking it to. Around half the openings we measure in 1970s-1990s Casey housing stock are out of square by 4mm or more, and a magnet strip on a bowed reveal leaves a gap you cannot see but can absolutely feel. The kit did not fail. The wall did. A professional retrofit panel is made to the measured opening, not to the nominal one, which is most of what you are paying for.
Worked example: one bedroom vs the whole house.
Scenario A - one medium bedroom window, 1,500mm x 1,100mm, in Hampton Park. DIY magnetic acrylic kit: about $180-$320 in materials plus a Saturday. Professionally fitted retrofit secondary panel from our pricing guide: $880-$1,400. The DIY option is roughly a quarter of the price and delivers perhaps 80 percent of the comfort improvement. For one room, DIY wins on any rational reading. Do it.
Scenario B - whole house, 16 openings, 1990s brick veneer in Cranbourne North. DIY across the lot: roughly $3,500-$5,000 in materials and realistically eight weekends, assuming nothing is out of square and you own a decent circular saw and a good straight edge. Our professional retrofit: $18,000-$26,000, less a VEU rebate of $2,500-$4,500 netted straight off the invoice, so call it $15,500-$22,500 out of pocket. You are still paying four to five times more.
What that difference buys is worth naming honestly rather than dressing up. A 10-year non-pro-rata seal warranty on every IGU. AS 2047 tested, wind-rated units that appear on a building surveyor's checklist and a conveyancer's. AS 1288 Grade A safety glass everywhere the law demands it. Documented NatHERS uplift for resale. And the fact that in year 12 you are not looking at sixteen yellowing acrylic panels wondering how to face redoing the lot. Whether that is worth the money is genuinely your call, not ours, and it depends on how long you are staying.
The rules DIY does not exempt you from.
Domestic building work under $10,000 in Victoria does not require a registered building practitioner, so small DIY work on your own home is lawful. But AS 1288 still applies to the glass: doors, sidelights, windows with a sill under 500mm and anything in a bathroom need Grade A safety glass, toughened or laminated, no exceptions and no grandfathering. AS 2047 still governs any new window unit you put in a wall. And if you sell, a building inspection will find non-compliant glass and it will become a price negotiation. The council - City of Casey for Berwick, Narre Warren, Cranbourne, Hampton Park and Endeavour Hills, Cardinia Shire for Beaconsfield, Officer and Pakenham - only gets involved if you widen an opening, which is structural and needs a building permit whoever swings the hammer. We keep the full reference list on our local trades and standards page.
The job to never DIY.
Taking a frame out of the wall. The instant the old unit leaves the opening you own the sill flashing, the head flashing lap, the packing, the square and the wind load. Get the flashing wrong on a west-facing wall and you will not find out until the second real storm, by which time the water is in the cavity and the plaster is bubbling. Reglazing an existing frame is a reasonable ambition for a competent DIYer. Frame replacement, of the kind covered on our double-glazed windows page, is not. If your frames are staying, our retrofit existing frames approach is the professional version of exactly what the DIY kits attempt. Local housing stock and which path suits it is covered on our Narre Warren page, and if you want to know what fails and when, see how long double glazing lasts.
DIY double glazing questions, answered straight.
Can I install double glazing myself in Victoria?
Legally, on your own home, you can do a lot of it. Domestic building work under $10,000 does not require a registered building practitioner in Victoria, so a small DIY secondary-glazing job is lawful. Two things are not negotiable regardless of who does the work: any glass in a door, sidelight, low-sill window or wet area must be Grade A safety glass to AS 1288, and any new window unit must be AS 2047 tested and wind-rated for the site. Where DIY goes wrong is almost never the law. It is the seal, the square and the drainage.
Do DIY magnetic secondary glazing kits actually work?
Yes, genuinely, and we say that as people who sell the alternative. A well-fitted acrylic magnetic kit on a single-glazed window will cut heat loss through that opening by roughly 40-50 percent and knock several decibels off traffic noise, for about $90-$160 per square metre in materials. The catch is that acrylic scratches, yellows after 8-12 years of Melbourne UV, and the whole thing lives or dies on whether your existing timber reveal is straight. On a wonky 1970s aluminium frame the magnet strip will not seal and you have wasted a weekend.
Will DIY double glazing void my VEU rebate?
It will not void anything, because you were never eligible to start with. The Victorian Energy Upgrades scheme creates certificates only where an accredited provider installs an approved product and lodges the paperwork. There is no self-install pathway and no retroactive claim. On a typical 15-20 window South East Melbourne retrofit the rebate nets $2,500-$4,500 off the invoice, which is often more than the entire materials cost of a DIY approach. That single fact reverses the maths on most whole-house jobs.
What is the one job I should never DIY?
Anything that involves taking a frame out of the wall. The moment the old unit leaves the opening you own the waterproofing, the flashing lap, the packing, the square and the wind load. Get the sill flashing wrong on a west-facing Cranbourne wall and you will not find out until the second big storm, when the water is already in the wall cavity and the plaster is bubbling. Reglazing an existing frame is a reasonable DIY ambition. Replacing a frame is not.
How much do I actually save doing it myself?
On a single medium window, a DIY magnetic acrylic kit costs about $180-$320 in materials against our $880-$1,400 for a professionally fitted retrofit secondary panel. That is a real saving and for one draughty bedroom it can be the right call. On a whole house of 16 openings the picture inverts: roughly $3,500-$5,000 in DIY materials and eight weekends, against a professional retrofit at $18,000-$26,000 less a $2,500-$4,500 VEU rebate, with a 10-year seal warranty, AS 2047 compliance and a result that survives a resale inspection.
Suburbs we measure in.
Not sure which side of the line your job sits on?
Ask us. If a DIY kit is the smarter buy for your situation we will say so at the measure - we would rather lose one window than sell you the wrong twenty.