Can You Build a Duplex on 451m² in NSW? A Complete Site Feasibility Checklist Short answer: Maybe — but square metres alone dont tell the full story. At giantA, we see builders and homeowners ask this exact question every week. The real answer depends on eight critical data sou... building-advice due-diligence duplex-development feasibility-study nsw-construction nsw-planning property-development site-assessment Jul 23, 2026