Converting a 2,000 sqft single-storey footprint into a 3-storey home of ~3,500 sqft is a major structural job, not just a simple reno. Expect a very rough ballpark of S$600,000 to S$1.5M+ for the full job, depending on how extensive and premium the works are.
Why the wide range
• If the existing structure needs heavy strengthening, new columns or pile works, costs jump quickly.
• Minimal, functional finishings bring you to the lower end. High-end finishes, bespoke joinery, new M&E, lift, or extensive plumbing push you to the top end.
• Professional fees, permit fees, GST and a sensible contingency must be factored in.
Typical cost breakdown (approx)
• Structural works & reengineering: 30–45% of budget.
• Superstructure, floors, roof: 20–30%.
• M&E (aircon, electrical, plumbing): 10–15%.
• Finishes & joinery: 15–25%.
• Professional fees (architect, structural engineer, QP, permits): 8–12%.
• Contingency: 10–15% (very important).
Other critical points
• Get a Qualified Person / architect first. They’ll tell you whether the current foundations and structure can take two extra storeys. Sometimes the cost of strengthening makes the job uneconomical.
• Approvals. You’ll need building plan approval from the authorities. Don’t underestimate time and conditions.
• Neighbours / boundary / party walls. Expect to coordinate and possibly get neighbour consent.
• Disruption and logistics. It’s messy. You’ll need a construction programme, safety measures, and possibly temporary accommodation.
• Timeline. Realistically plan for 9 to 18 months from detailed design to practical completion, depending on complexity and approval times.
• Resale / value. An extra storey adds value but not necessarily dollar for dollar. Consider whether the cost meets your long term goals.
Practical next steps (what I’d do)
1. Engage a QP / architect for a site inspection and feasibility report.
2. Get a structural survey and preliminary cost plan.
3. If feasible, apply for planning/building approvals while you get 2–3 contractor tenders.
4. Lock in a contractor with clear milestones, a defects liability clause and staged payments.
5. Keep a 10–15% contingency aside for surprises.
If you want, I can introduce you to reliable QPs and contractors I trust, or arrange a site visit to get a proper feasibility quote.
Aren Goh | PropNex
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