How much you can build on a residential lot in NSW under complying development depends mainly on the lot’s area and width. The Housing Code sets the maximum gross floor area of all buildings (clause 3.9), the minimum landscaped area (clause 3.13), front, side and rear setbacks (clause 3.10) and an 8.5 metre, two storey height limit. There is no site coverage percentage. Granny flats are tested against the Housing SEPP, which generally needs a lot of at least 450 square metres. Side by side duplexes are tested against the Low Rise Housing Diversity Code, which needs at least 400 square metres and usually a 15 metre width. Our free How much can I build? CDC calculator applies those standards to the frontage, depth and area you enter and gives an indicative answer in under two minutes. It is a quick guide, not an approval: land exclusions, heritage, bushfire, flood and covenants can rule complying development out regardless of the numbers.
Key takeaways
- Under the Housing Code, a lot must generally be at least 200 square metres and 6 metres wide at the building line, in zone R1, R2, R3, R4 or RU5, to be eligible for complying development.
- The maximum gross floor area of all buildings ranges from 78% of lot area on 200 to 250 square metre lots to a cap of 400 square metres on lots over 1,000 square metres (clause 3.9).
- Minimum landscaped area rises with lot size, from 10% of the lot up to 300 square metres to 45% over 1,500 square metres (clause 3.13).
- The calculator also checks granny flat lot size and frontage, and duplex lot size, width and floor area, and flags site constraints you tick.
- Results are indicative general information; a section 10.7 planning certificate and a professional review are needed before you design, buy or lodge.
Who this is for: home owners, buyers, investors and builders in Sydney, the Central Coast, the Hunter, the Illawarra and regional NSW who want a quick, sourced answer to “how much can I build on my lot?” before paying for design or a full site review.
What does the calculator ask for?
- Your project. A new house or knock-down rebuild, alterations and additions, a house plus a granny flat, a granny flat behind an existing house, or a side by side duplex.
- The lot. Zone, frontage (width at the building line), depth and area. If you only know frontage and depth, it multiplies them; use the area on the deposited plan if you have it. Tick corner lot or battle-axe lot, and for a battle-axe lot enter the access handle’s area and width.
- The site. Address, suburb, postcode, council, and any constraints you know of: heritage, bushfire, flood, easements, main road, acid sulfate soils, aircraft noise, no sewer or a covenant.
- Your details. Name, phone and email, so we can follow up if you want, and an optional tick if you would like a call or a quote. Temporary and disposable email addresses are not accepted.
What does the result show?
| Result item | Where it comes from |
|---|---|
| Eligibility checks (zone, minimum lot size, width, battle-axe rules) | Housing Code lot requirements; Housing SEPP Schedule 1 for granny flats; Low Rise Housing Diversity Code for duplexes |
| Maximum gross floor area | Housing Code clause 3.9, or clause 3B.10 for duplexes |
| Minimum landscaped area | Housing Code clause 3.13, or clause 3B.15 for duplexes |
| Front, side, rear and corner setbacks | Housing Code clause 3.10 |
| Height, storeys, open space, parking and garage door width | Housing Code clauses 3.1, 3.8, 3.13 and 3.16 |
| Indicative ground floor envelope | Our geometry from the setbacks on a rectangular lot |
| Warnings for constraints you ticked | Codes SEPP clauses 1.17A to 1.20 (land exclusions) |
The result is colour coded: green where the basics look met, amber where something needs checking, and red where a requirement appears not to be met and a development application (DA) is the more likely pathway.
Why is there no “site coverage” figure?
Many people ask about site coverage, because older codes and many council DCPs use it. The current Housing Code does not. It controls how much you can build through the maximum gross floor area, the minimum landscaped area, setbacks and height. The calculator therefore reports those figures and an indicative ground floor envelope from the setbacks, rather than a coverage percentage. Council DCPs still use site coverage for DAs, so a DA design may be assessed differently.
A worked example: 10.5 m by 30 m in an R2 zone
A 315 square metre lot, 10.5 metres wide, for a new two storey house:
- maximum gross floor area: 235 square metres (the fixed amount for lots over 300 to 350 square metres);
- minimum landscaped area: 47 square metres (15%);
- front setback: 4.5 metres, or the average of the two nearest dwellings within 40 metres;
- rear setback: 3 metres for parts up to 4.5 metres high, 8 metres above that;
- side setbacks: 0.9 metres for the lower part of the building, more for higher parts; a wall on one side boundary may be possible, subject to conditions;
- private open space: 24 square metres; one car space; garage door up to 3.2 metres facing the street.
The setbacks leave an indicative ground floor envelope of about 8.7 by 22.5 metres. With 47 square metres of landscaping and open space to fit as well, the 235 square metre floor area is usually reached with a second storey.
What the calculator cannot tell you
It cannot read your planning certificate, the Schedule 5 exclusion maps, council variations, covenants and easements on title, slope, trees, the bushfire attack level or flood levels, or the detailed design standards such as privacy, articulation and earthworks. Any of these can change the answer. That is why every result carries a disclaimer and an option to ask for a professional review.
Definitions
- Complying development
- Development that meets every standard in the relevant code and can be approved by a council or registered certifier through a complying development certificate.
- Housing Code
- Part 3 of State Environmental Planning Policy (Exempt and Complying Development Codes) 2008, covering new houses and alterations and additions.
- Building line
- The line of the front of the house facing the primary road, where lot width is measured.
- Landscaped area
- Area of the lot used for landscaping, with minimum dimensions, that counts towards the clause 3.13 minimum.
Frequently asked questions
Is the CDC calculator free?
Yes. It asks for your contact details before showing the result so a planner can follow up if you want help, and you can tick a box if you would like a call or quote.
Does a green result mean I can get a CDC?
No. It means the basic numbers look met on what you entered. Land exclusions, title restrictions and detailed design standards still need checking by a planner or certifier.
Can I use the calculator for a duplex?
Yes, for a side by side dual occupancy under the Low Rise Housing Diversity Code. It checks the 400 square metre minimum (or the LEP minimum you enter), the lot width and the maximum floor area.
Where do I find my lot’s zone and area?
The zone is on the section 10.7 planning certificate and the NSW Planning Portal spatial viewer. The area is on the deposited plan, a survey or the contract for sale.
Try the CDC calculator for your lot, and if the result is amber or red, or you want certainty before buying, our development due diligence report confirms the pathway and the yield. To talk it through, request a fee proposal.
Sources and references
- State Environmental Planning Policy (Exempt and Complying Development Codes) 2008, Part 1, Part 3 Housing Code and Part 3B Low Rise Housing Diversity Code, accessed October 2026
- NSW Department of Planning and Environment, Guide to Complying Development (August 2023), accessed October 2026
- State Environmental Planning Policy (Housing) 2021, Chapter 3 and Schedule 1 (secondary dwellings), accessed October 2026
- NSW Planning Portal, Spatial viewer, accessed October 2026
Information disclaimer. This article is general planning information prepared by the URBA Planning Team and is current at the date of publication. It is not planning, legal or financial advice for any specific property. Planning instruments, development control plans, state policies and the National Construction Code are amended regularly and councils interpret them differently; the controls quoted here should be confirmed against the versions in force at the date of lodgement and against the consent authority’s current requirements. Reliance on this article is at the reader’s own risk. URBA Planning, a division of Contrive Consultants Pty Ltd, accepts no liability for loss arising from its use. For advice on a specific site, contact URBA for a fee proposal.