How Long Does It Take to Build a Granny Flat in Sydney?
A granny flat in Sydney takes 4–8 months from design to handover. The total project timeline breaks down into three main phases: design and approvals (4–8 weeks), site preparation (1–2 weeks), and construction (12–20 weeks).
The biggest variable is the approval pathway. A CDC (Complying Development Certificate) takes 10–15 business days. A DA (Development Application) through your local council takes 40–90+ business days — sometimes longer if additional information is requested.
Buildana (Lic. 487805C) has completed hundreds of granny flats across Western Sydney. Our streamlined process — parallel design-and-approval documentation, pre-ordered materials, and dedicated site supervisors — consistently delivers on or ahead of schedule.
Phase 1: Design and Approvals (4–8 Weeks)
This is where your granny flat goes from concept to approved plans:
Weeks 1–2: Site Assessment and Design • Site inspection, survey, and soil test • Concept floor plan and elevations • BASIX modelling and compliance strategy • Client review and design refinement
Weeks 3–4: Documentation • Construction drawings and specifications • BASIX certificate lodgement • Engineering (slab, footings) • CDC or DA application package
Weeks 4–6: Approval • CDC: 10–15 business days from lodgement • DA: 40–90+ business days from lodgement
Buildana lodges CDC applications within 3 weeks of signing. If your site requires a DA (heritage overlay, bushfire zone, flood-prone land), we manage the full process including any council requests for additional information.
While waiting for approval, Buildana pre-orders long-lead materials (windows, kitchen, bathroom fixtures) to eliminate delays once construction begins.
Phase 2: Site Preparation (1–2 Weeks)
Once approval is granted, site preparation begins:
Week 1: • Demolition of existing structures (shed, garage, old concrete) • Tree removal or protection (as per approval conditions) • Temporary fencing and site access setup • Excavation and level pad preparation
Week 2: • Sewer and stormwater rough-in • Electrical conduit installation • Anti-termite treatment • Slab reinforcement and formwork • Concrete pour
Site preparation can take longer if your block has challenging soil (Class H or P), significant level changes requiring retaining walls, or complex sewer/stormwater diversions. Buildana identifies these during the site assessment so there are no surprises.
Phase 3: Construction (12–20 Weeks)
Construction follows a predictable sequence:
Weeks 1–3: Frame and Roof • Wall frame erection (timber or steel) • Roof trusses and sheeting • External cladding started • Windows and external doors installed
Weeks 4–6: Lock-Up • External cladding completed • Fascia, gutters, and downpipes • Building is weather-sealed (lock-up stage)
Weeks 7–10: Internal Fit-Out • Electrical rough-in (wiring, switch plates) • Plumbing rough-in (hot/cold water, drainage) • Internal wall linings and ceiling • Insulation • Waterproofing (bathroom/laundry) • Tiling
Weeks 11–14: Finishing • Kitchen and bathroom installation • Painting • Flooring • Built-in robes • Final electrical and plumbing fit-off • External landscaping and paths
Weeks 15–16: Handover • Final inspection and defect check • Occupation Certificate • Client walkthrough and handover
A 1-bedroom granny flat (36–40 sqm) typically completes in 12–14 weeks of construction. A 2-bedroom (50–60 sqm) takes 16–20 weeks. Buildana provides a week-by-week construction schedule in every contract.
What Causes Delays — and How to Avoid Them
Common causes of granny flat construction delays:
• Slow council DA processing: Choose CDC where possible — 10–15 days vs 40–90+ days • Incomplete documentation: Buildana lodges complete applications first time • Client change orders during construction: Finalise your design before approval lodgement • Weather: Extended rain can delay slab pours and external work by 1–2 weeks • Material supply issues: Pre-ordering long-lead items during approval avoids this • Unexpected site conditions: Thorough site assessment catches most issues upfront
Buildana's process is designed to avoid the most common delays. Our design-to-approval timeline is 3–4 weeks (CDC), and our construction team maintains a forward schedule with materials ordered ahead of each stage.
Ready to start? Book a free consultation at /contact and we'll provide a site-specific timeline for your granny flat project.
