Extensions & Additions

Why extend your home?

Life changes — growing families, working from home, ageing parents moving in, teenagers needing their own space. Extensions let you stay in the location you love, keep the kids in their schools, and avoid the stress and cost of moving. A well-designed extension adds functional space and typically returns 70–90% of cost in resale value (Domain 2025 data for NSW coastal markets).

What we build

What's included in the price

• Fixed-price contract (HIA Renovations Contract standard form — no variations unless you request scope changes)
• Structural engineer assessment and certification (mandatory for second-storey and large extensions)
• Development Application (DA) or Complying Development Certificate (CDC) lodgement and approval management
• Construction Certificate (CC) application
• BASIX certificate (if triggered by floor area increase)
• All materials, labour, and site supervision
• Roof tie-in and weatherproofing (matching existing roof profile where possible)
• Electrical rough-in and final connection (switchboard upgrade if required — quoted separately)
• Plumbing rough-in and final connection
• Insulation (minimum R2.5 walls, R3.5 ceiling — NSW Building Code 2025)
• Internal lining (plasterboard, cornice, paint — 3 coats Dulux Wash & Wear or equivalent)
• Flooring (carpet, vinyl plank or tiles — allowance-based, upgraded finishes quoted separately)
• 6.5-year structural warranty (HIA standard)

Typical timeline & payment milestones

A standard rear or side extension runs 4–6 months from contract signing to handover. Payment milestones follow the HIA Renovations Contract schedule:

1. Deposit (10%): On contract signing.
2. Base stage (25%): Foundation complete and inspected.
3. Frame stage (25%): Frame, roof and external cladding complete.
4. Lock-up stage (25%): Windows, doors, plumbing and electrical rough-in complete, internal lining started.
5. Practical completion (10%): Final finishes, clean, handover and final inspection.
6. Final (5%): 5 business days after practical completion, once any minor defects list is addressed.

Second-storey additions run 6–9 months due to structural complexity and longer approval times. You continue living in the home during construction — we section off the work area, maintain daily site clean-up, and coordinate noise-intensive work (sawing, drilling) to minimise disruption.

Planning + approvals

Extensions trigger council approval in most cases. We handle the full process:

• Complying Development Certificate (CDC): Fastest path (10–20 business days approval). Available if your extension meets prescriptive rules (e.g. rear setback ≥6m, height ≤8.5m, floor area increase ≤50m² ground floor or ≤30m² upper floor). We work with an accredited certifier to confirm eligibility and lodge.
• Development Application (DA): Required if CDC doesn't apply (e.g. heritage area, large extension, non-standard setback). Typical approval time: 6–12 weeks. We engage the architect/designer, prepare the DA pack (plans, BASIX, stormwater, neighbour notification), lodge with council, and respond to any information requests.
• Construction Certificate (CC): Required before starting on-site work. Issued by council or a private certifier once the DA is approved and detailed construction plans are submitted. Typical turnaround: 2–3 weeks.

Cost: DA + CC fees are additional to the build contract — typically $4,000–$8,000 (council DA), $2,500–$4,000 (CDC), $1,500–$2,500 (CC), $800–$1,500 (structural engineer report), $300–$600 (BASIX certificate if required). We provide a fixed quote for approval costs upfront as part of the initial scope discussion.

What clients say