Licensed Builder · NSW 355555C · Greater Sydney
Home Extensions & Additions Sydney
Ground floor rear extensions, second storey additions, and room additions across Greater Sydney. DA and CDC managed. Concept to handover under one contract.
State Property Development builds home extensions and additions across Greater Sydney. NSW Builders Licence 355555C. $20M public liability. Whether you want to push the back of the house out for a larger open-plan living area, add a second storey, or build a separate studio – we manage the project from approvals through to handover.
Extensions in NSW require either a DA (Development Application) or CDC (Complying Development Certificate) before construction starts. We advise on which pathway applies to your site before you spend money on architect fees, so you’re not caught six months in with the wrong approval type.
What We Build
- Ground floor rear extensions – kitchen, living, open-plan
- Second storey additions – bedrooms, bathrooms, study
- Side extensions and room additions
- Garage conversions and studio additions
- Deck and alfresco extensions integrated with the structure
What Affects the Cost
Every extension is priced individually – ground floor and second storey additions differ significantly in structural complexity, and no two sites are the same. Key factors include:
- Extension type: ground floor rear, second storey addition, or side extension
- Floor area and layout complexity
- Structural requirements: particularly for second storey additions, where lower-level strengthening may be needed
- Level of finish selected
- Engineering, DA/CDC, and design fees, which are engaged separately but coordinated by us
Use our Free Preliminary Building Estimate tool for a ballpark figure, or contact us for a tailored assessment.
DA vs CDC – Which Do You Need?
A CDC is faster – typically 10–20 days – but only applies if your extension meets the standards in the NSW Housing Code (lot size, setbacks, floor space ratio, height). Extensions that don’t meet CDC criteria need a DA, which takes 40–90+ days at most Sydney councils. We look at your site specifics – lot dimensions, zoning, existing floor area, setbacks – and advise you on which pathway before you pay for design.
→ Want a ballpark figure for your project? Get a free preliminary estimate
Disclaimer: All information on this website is indicative only and provided as a general guide. Final construction costs will vary depending on architectural design, structural engineering requirements, hydraulic design, BASIX/NatHERS compliance, geotechnical (soil) reports, site conditions, council or certifier requirements, selected finishes, inclusions, and overall project scope. A detailed quotation can only be provided once all relevant plans, reports, and specifications have been completed and reviewed.
Home Extension FAQs
Every extension is individually assessed and priced according to its design, scope, site conditions, and required level of finishes. Ground floor and second storey additions differ significantly in structural complexity. Get a free preliminary estimate or contact us directly for a tailored figure.
Yes – either a CDC (10–20 days, if your site meets NSW Housing Code standards) or a DA (40–90+ days at most councils). We look at your site dimensions, zoning, and existing floor area before you pay for design, so you know which path you’re on.
Ground floor 30–60sqm: 12–18 weeks of construction. Second storey: 16–24 weeks. Total project time including design, engineering, and DA is typically 6–12 months from decision to handover. We give you a realistic programme before you commit.
Usually yes, for ground floor extensions. When the roof is open for new structural connections – typically 1–3 weeks – temporary weather protection is required. For second storey additions, the existing roof is removed and rebuilt, which requires careful weatherproofing management. We plan this as part of the construction sequence.
Home Extension Enquiry – Sydney
Licensed builder. DA and CDC advice before you pay for design. NSW Licence 355555C. $20M public liability.