Do I need a planning permit to extend my house in Knox?
Checked against the Knox Planning Scheme as at 02/10/2026
Not always. In Knox's residential zones, the scheme requires a planning permit to extend one dwelling only on a lot under 300 square metres. Overlays (heritage, design and development, significant landscape and flooding) can require one on any lot, and a building permit is a separate approval.
This describes what Knox's planning scheme generally states, as last checked by PolicyPing. It isn't a site-specific assessment or a substitute for advice from a licensed practitioner. For your specific address, see ReefReport. Read the full methodology.
The answer depends on your lot. Zone, lot size and overlays change it address by address.
Buying or building in Knox? Screen the site first: zone, overlays, height limit and what the land allows, in plain English.
Zone, lot size and overlay triggers
Each row below is read from the Knox Planning Scheme's own clause text. Rows appear only for the zones and overlays that have a schedule in this scheme.
| Control | What the scheme text says | Clause |
|---|---|---|
| Low Density Residential Zone (LDRZ), 1 schedule | The buildings and works clause lists the permit triggers: buildings and works associated with a Section 2 use, and an outbuilding with dimensions greater than those in a schedule to the zone. Extending a dwelling is not listed. | Clause 32.03-4 |
| Mixed Use Zone (MUZ), 3 schedules | A permit is required to construct or extend one dwelling on a lot less than 300 square metres. A development must meet the requirements of Clause 54. | Clause 32.04-5 |
| Residential Growth Zone (RGZ), 3 schedules | A permit is required to construct or extend one dwelling on a lot less than 300 square metres. A development must meet the requirements of Clause 54. | Clause 32.07-4 |
| RGZ building height | Where a schedule sets no maximum, the building height should not exceed 13.5 metres. An extension to an existing building may exceed the maximum if it does not exceed the height of the existing building. The requirement applies whether or not a planning permit is required. | Clause 32.07-10 |
| General Residential Zone (GRZ), 5 schedules | A permit is required to construct or extend one dwelling on a lot less than 300 square metres. A development must meet the requirements of Clause 54. | Clause 32.08-5 |
| GRZ building height | Where a schedule sets no maximum, the building height must not exceed 11 metres and the building must contain no more than 3 storeys. An extension to an existing building may exceed the maximum if it does not exceed the height or number of storeys of the existing building. The requirement applies whether or not a planning permit is required. | Clause 32.08-11 |
| GRZ minimum garden area | An application to construct or extend a dwelling on a lot must provide a minimum garden area: 400 to 500 sqm, 25%; Above 500 to 650 sqm, 30%; Above 650 sqm, 35%. | Clause 32.08-4 |
| Neighbourhood Residential Zone (NRZ), 8 schedules | A permit is required to construct or extend one dwelling on a lot less than 300 square metres. A development must meet the requirements of Clause 54. | Clause 32.09-5 |
| NRZ building height | Where a schedule sets no maximum, the building height must not exceed 9 metres and the building must contain no more than 2 storeys. An extension to an existing building may exceed the maximum if it does not exceed the height or number of storeys of the existing building. The requirement applies whether or not a planning permit is required. | Clause 32.09-11 |
| NRZ minimum garden area | An application to construct or extend a dwelling on a lot must provide a minimum garden area: 400 to 500 sqm, 25%; Above 500 to 650 sqm, 30%; Above 650 sqm, 35%. | Clause 32.09-4 |
| Heritage Overlay (HO), 1 schedule, 50 HO-numbered places listed | A permit is required to construct a building or construct or carry out works, and to demolish or remove a building. | Clause 43.01-1 |
| Design and Development Overlay (DDO), 12 schedules | A permit is required to construct a building or construct or carry out works, unless a schedule to the overlay specifically states that a permit is not required. A schedule can also set requirements such as building setbacks and building height. | Clause 43.02-2 |
| Significant Landscape Overlay (SLO), 6 schedules | A permit is required to construct a building or construct or carry out works, unless a schedule to the overlay specifically states that a permit is not required. | Clause 42.03-2 |
| Environmental Significance Overlay (ESO), 2 schedules | A permit is required to construct a building or construct or carry out works, unless a schedule to the overlay specifically states that a permit is not required. | Clause 42.01-2 |
| Vegetation Protection Overlay (VPO), 4 schedules | The permit requirement is to remove, destroy or lop vegetation specified in a schedule to the overlay. | Clause 42.02-2 |
| Special Building Overlay (SBO), 1 schedule | A permit is required to construct a building or to construct or carry out works, unless a schedule to the overlay specifically states that a permit is not required. The clause exempts an extension of less than 20 square metres in floor area to an existing building (not an out-building) where the floor levels are at least 300mm above the flood level, or the floodplain management authority has agreed in writing that the flowpath is not obstructed. It also exempts an upper storey extension to an existing building. It also exempts an alteration where the original building footprint stays the same and floor levels are at least 300mm above flood level. | Clause 44.05-2 |
| Land Subject to Inundation Overlay (LSIO), 1 schedule | A permit is required to construct a building or to construct or carry out works, unless a schedule to the overlay specifically states that a permit is not required. The exemptions the clause itself lists cover roadworks and bicycle paths, flood mitigation works, underground services and power lines, and post and wire or post and rail fencing. None of them is a dwelling extension. | Clause 44.04-2 |
| Floodway Overlay (FO), 1 schedule | A permit is required to construct a building or to construct or carry out works, unless a schedule to the overlay specifically states that a permit is not required. | Clause 44.03-2 |
| Bushfire Management Overlay (BMO), 2 schedules | A permit is required to construct a building or construct or carry out works associated with listed uses, which include accommodation. The clause exempts an alteration or extension to an existing dwelling or small second dwelling provided the gross floor area is not increased by more than 50 percent. | Clause 44.06-2 |
| Development Plan Overlay (DPO), 14 schedules | A permit must not be granted to construct a building or construct or carry out works until a development plan has been prepared to the responsible authority's satisfaction, unless a schedule specifically states that a permit may be granted before then. | Clause 43.04-2 |
| Public Acquisition Overlay (PAO), 1 schedule | A permit is required to construct a building or construct or carry out works, to damage, demolish or remove a building or works, and to use or subdivide land. | Clause 45.01-1 |
| Restructure Overlay (RO), 1 schedule | A permit is required to construct or extend a dwelling or other building. It must be in accordance with the restructure plan listed in the schedule, unless no restructure plan is listed and the permit is to extend an existing dwelling or other building. | Clause 45.05-2 |
Planning permit or building permit?
A planning permit and a building permit are two separate approvals. Having one does not mean you have the other.
- Planning permit. Decided by the council against the Knox Planning Scheme. This page covers only whether the scheme requires one.
- Building permit. Issued by a registered building surveyor under the Building Act 1993 and the building regulations. The planning scheme does not decide it, and PolicyPing's scheme text does not cover it, so this page does not say whether your extension needs one.
The scheme itself keeps the two apart: its maximum building height requirement applies "whether or not a planning permit is required for the construction of a building" (Clause 32.04-12).
Exemptions and variations
Exemptions in the zone clauses
- Mixed Use Zone (Clause 32.04-5), Residential Growth Zone (Clause 32.07-4), General Residential Zone (Clause 32.08-5) and Neighbourhood Residential Zone (Clause 32.09-5): no permit is required to construct or carry out works normal to a dwelling; make structural changes to a dwelling, provided the size of the dwelling and the number of dwellings are not increased; construct or extend an out-building (other than a garage or carport) of no more than 10 square metres in gross floor area and no more than 3 metres high.
Variation specific to Knox
- Permit threshold for extending one dwelling: no council-specific variation. Every residential zone clause in the Knox scheme that sets a threshold states 300 square metres.
- Maximum building height: 2 schedules set their own requirement.
- GRZ7: "A building used as a dwelling, small second dwelling or a residential building must not exceed a height of 16 metres and 5 storeys."
- GRZ8: "A building used as a dwelling, small second dwelling or a residential building must not exceed a height of 14 metres and 4 storeys."
- Clause 54 street setback, site coverage, private open space and front fence standards: 7 schedules vary a standard. The figures are in each schedule's text.
- NRZ1: sets its own front fence height
- NRZ2: sets its own front fence height
- NRZ3: sets its own front fence height
- NRZ4: sets its own front fence height
- NRZ5: sets its own front fence height
- NRZ7: sets its own minimum street setback and front fence height
- NRZ9: sets its own front fence height
- Exemption from the minimum garden area requirement (GRZ): no council-specific variation. No GRZ schedule in this scheme exempts the construction or extension of a dwelling.
Overlay schedules in the Knox scheme: HO 1, DDO 12, SLO 6, ESO 2, VPO 4, SBO 1, LSIO 1, FO 1, BMO 2, DPO 14, PAO 1, RO 1. What a particular overlay schedule requires for a lot is set in that schedule, and the overlay rows in the table above are the general requirement from the overlay clause.
What this page could not verify
These items are unresolved on this page, each with the reason.
- Extension triggers in Rural Living Zone (Clause 35.03), Green Wedge Zone (Clause 35.04), Rural Conservation Zone (Clause 35.06), Farming Zone (Clause 35.07). Unresolved because these zones set their extension rules through floor-area limits that a schedule can change, and this page has not read each schedule's figure, so no threshold is stated for them.
- Which zone, schedule and overlays cover your lot. Unresolved because that comes from the planning scheme maps, which PolicyPing's parsed scheme text does not include.
- What each overlay schedule requires for your lot. Unresolved because an overlay schedule can state that no permit is required or set its own requirements, and this page has not read each schedule's wording.
- Overlays with schedules that this page names but does not analyse: Specific Controls Overlay (Clause 45.12). Unresolved because their schedules set controls case by case and have not been read for extension triggers.
- Particular provisions, general provisions and restrictive covenants. Unresolved because they sit outside the zone and overlay clauses this page reads, so no statement is made about them.
What happens next
Work out which zone, schedule and overlays cover your lot, then read each against the table above. Where an overlay applies, its schedule can set requirements specific to your lot. Where a permit is needed, the council decides the application against the scheme.
Frequently asked questions
Do I need a planning permit to extend my house in Knox?
Not always. In Knox's residential zones, the scheme requires a planning permit to extend one dwelling only on a lot under 300 square metres. Overlays (heritage, design and development, significant landscape and flooding) can require one on any lot, and a building permit is a separate approval.
What is the difference between a planning permit and a building permit?
A planning permit is decided by the council against the Knox Planning Scheme. A building permit is issued by a registered building surveyor under the Building Act 1993 and the building regulations. Having one does not mean you have the other.
Which overlays can require a planning permit for an extension in Knox?
The Knox scheme has schedules to the Heritage Overlay (HO), Design and Development Overlay (DDO), Significant Landscape Overlay (SLO), Environmental Significance Overlay (ESO), Vegetation Protection Overlay (VPO), Special Building Overlay (SBO), Land Subject to Inundation Overlay (LSIO), Floodway Overlay (FO), Bushfire Management Overlay (BMO), Development Plan Overlay (DPO), Public Acquisition Overlay (PAO) and Restructure Overlay (RO). Each overlay clause sets its own permit requirement, set out in the table on this page, and a schedule can change what applies to a lot.
Does lot size change whether I need a planning permit?
Yes. The residential zone clauses in the Knox scheme require a permit to extend one dwelling only on a lot less than 300 square metres. Overlays can apply to a lot of any size.
Analysis. The Knox Planning Scheme is the source of every control on this page, and the clause wording is quoted or closely paraphrased from it. The framing sentences are PolicyPing's own reading of that text. The scheme states these controls in general terms. It does not assess any particular lot and is not a substitute for advice from a licensed practitioner.
The answer depends on your lot. Zone, lot size and overlays change it address by address.
Buying or building in Knox? Screen the site first: zone, overlays, height limit and what the land allows, in plain English.