Do you need a permit to replace windows in Casey?
Most Berwick jobs need nothing at all. Swap a window for the same window in the same hole and you are exempt. The permit questions start when the opening changes shape, when the title carries a heritage overlay, or when the block sits in a bushfire-prone area. Here is exactly where each line falls.
Like-for-like is the magic phrase.
Schedule 3 of the Building Regulations 2018 lists the work that does not need a building permit, and repair or replacement of an existing window in an existing opening sits inside it. Same hole, same size, same operating type, no structural change. That single exemption covers the great majority of what we do across Berwick, Cranbourne and Narre Warren: builder-spec 1990s and 2000s aluminium coming out, better aluminium going back in the same opening.
Note what the exemption does not do. It does not exempt you from the standards. AS 2047 still governs the window's wind load, water penetration resistance and operating force, and every unit we install carries the label. AS 1288 still dictates where Grade A toughened or laminated glass is mandatory: within 500mm of floor level in a habitable room, beside doors, in wet areas. A permit-exempt job that puts annealed glass beside a door is still an unlawful job. The exemption is about paperwork, not about quality.
What tips you into needing a building permit.
- Enlarging the opening. Widening a 2.4m slider to a 3.6m stacker means a new lintel and a structural change. Permit. This is the single most common trigger we see, and it is covered in detail on our stacker door upgrade page.
- Adding a window to a wall that did not have one.
- Filling one in and re-cladding or re-bricking the wall.
- Converting types across a structural line, such as a window to a doorway, or a slider to French doors where the head height changes.
- Anything that changes the building's energy or bushfire performance as part of wider permitted work.
A building permit does not come from the council. It comes from a private building surveyor, who assesses the design, issues the permit, inspects at the mandatory stages and lodges the paperwork with the City of Casey. Two to three weeks is typical and $700 to $1,800 is the usual 2026 range for domestic window work. If a structural opening is involved you will also need an engineer's lintel design, which is another $600 to $1,200.
Heritage and bushfire: the two Casey overlays that bite.
A planning permit is a different animal from a building permit. It comes from the City of Casey, and it answers a different question: not whether your window is sound, but whether you are permitted to change the look or the performance of the building at all. Check your planning property report before you choose a product, because the overlay decides the product for you.
The Berwick Village heritage overlay.
Parts of old Berwick, principally the original township fabric around High Street, sit under a heritage overlay. If your title carries one, you cannot change the street-facing appearance of a window without a planning permit. In practice council will expect timber sash to stay timber sash, with the original profile, sight lines, glazing bar pattern and frame colour reproduced. Aluminium in a Victorian cottage frontage gets refused, and rightly so, because it looks wrong from the footpath and it is irreversible.
The good news for heritage owners is that comfort and compliance are no longer opposed. Slimline insulated glass units now fit into heritage-appropriate timber sash profiles that would not have taken a standard IGU a decade ago, so you can hold the streetscape and still stop the condensation. Our timber windows page covers the joinery, the species and the profiles we use for period-matched work. Budget $1,200 to $2,400 per small sash and $2,400 to $3,800 for medium, against $580 to $1,800 for the aluminium equivalent you are not allowed to use.
The bushfire management overlay and AS 3959.
The foothill blocks, Harkaway, Narre Warren North, the treed northern edge of Berwick running up toward the Dandenong ranges, sit in bushfire-prone areas and many carry a bushfire management overlay. AS 3959 sets the construction requirements by Bushfire Attack Level, and windows are one of the most heavily specified elements in the standard because radiant heat and ember attack both come through glazing first. BAL-12.5 and BAL-19 are the common ratings across those Casey blocks. At those levels you are looking at toughened glass to specified thicknesses, screening requirements, and frame material restrictions, and the cost lands roughly 25 to 60 per cent above a standard equivalent depending on the rating.
The trap is inconsistency. AS 3959 works on the whole envelope, so new BAL-rated windows sitting beside an unrated garage door or an unrated side panel do not give you a compliant house. If you are doing windows and another envelope element in the same year, share the BAL certificate between the trades. Our local trades page covers how that coordination works across Casey.
What the paperwork actually costs you.
Planning is the slow half. A straightforward single-dwelling alteration application to the City of Casey is realistically six to twelve weeks, longer if it needs advertising to neighbours. Planning application fees are set by state regulation rather than by council whim, and for alterations to a single dwelling they generally sit anywhere from the low hundreds up to around $1,300 depending on the declared value of works, plus council administration costs. Building permits through a private surveyor are the fast half at two to three weeks.
Worked example, 2026. Weatherboard cottage off High Street, Berwick, heritage overlay, six original timber sash windows with rotted bottom rails and two that no longer close. The owner wants aluminium because it is cheaper. Council will not have it, so the scope becomes six period-matched timber sash units with slimline double glazing at $2,200 each, $13,200. Planning permit application and drawings: about $1,400 all up. Building permit: not required, because it is like-for-like in existing openings once the material is settled. Reveal and architrave make-good on a 1900s plaster reveal at $380 per opening: $2,280. Total about $16,880, and roughly fourteen weeks from first call to finished, of which ten weeks is the planning permit and the timber lead time running in parallel. Had the same owner ordered aluminium off a website without checking the overlay, they would have paid a deposit on frames they could never legally install.
That is the whole reason we check the overlay before we quote, not after. It takes about five minutes on the planning property report and it decides the material, the price and the timeline. We handle the surveyor engagement on jobs that need one and lodge the planning application on heritage work across the City of Casey. If you just want to know what your job costs before you get into any of this, the Berwick window pricing guide has the per-opening bands.
Permit questions we get asked.
Do I need a building permit to replace windows in the City of Casey?
For a straight like-for-like swap, generally no. Replacing a window in the same opening, at the same size, in the same operating type falls under the maintenance and repair exemptions in Schedule 3 of the Building Regulations 2018, and the overwhelming majority of Berwick and Cranbourne jobs are exactly that. You need a building permit the moment the opening itself changes: enlarging it, adding a new window to a wall, filling one in, or converting a slider to French doors. That is because you are touching the structure and the energy performance of the wall, not just the unit sitting in it.
Is a planning permit different from a building permit?
Completely different, issued by different people, and you can need both. A planning permit comes from the City of Casey and is about whether you are allowed to do it at all, given the overlays on your title. A building permit comes from a private building surveyor and is about whether what you are building is structurally and legally sound. Planning first, building second. In Casey the overlays that catch window work are the heritage overlay over parts of old Berwick and the bushfire management overlay across the foothill blocks.
What are the heritage overlay rules for windows in Berwick Village?
If your title carries a heritage overlay, you cannot change what a window looks like from the street without a planning permit from the City of Casey. In practice that means timber sash stays timber sash, the profile, the sight lines, the glazing bar pattern and the frame colour all have to match the original, and swapping to aluminium is refused. Double glazing is often achievable in a heritage-appropriate timber frame, and slimline IGUs have made that easier than it was ten years ago. Check the overlay on your planning property report before you fall in love with a product.
How long does a window permit take in Casey and what does it cost?
A building permit through a private surveyor is typically two to three weeks and lands in the $700 to $1,800 range for domestic window work in 2026. A planning permit through the City of Casey is the slow one: six to twelve weeks is realistic for a straightforward single-dwelling application, longer if it goes to advertising. Planning application fees are set by state regulation and for alterations to a single dwelling generally sit in the low hundreds to around $1,300 depending on the value of works, plus council administration costs.
Do replacement windows have to meet current energy standards?
Where a permit is triggered, yes, the new work has to meet the energy provisions of the National Construction Code in force now, and Casey sits in Climate Zone 6 where double glazing is the practical baseline. For permit-exempt like-for-like swaps there is no NCC energy trigger, so you can legally refit single glazing. We would still talk you out of it. The whole cost of the job is the removal, the frame and the make-good, and the double-glazing upgrade on top of that is only a few hundred dollars per opening.
Permit and overlay work across Casey.
We check the overlay before we quote.
Free measure, overlay check, and the permit path in writing before you pay a deposit on anything.