How To Make Roofing Cost Estimate ?
How to Build a Roofing Cost Estimate in Singapore
Singapore’s hot, humid climate and the high concentration of high‑rise buildings mean that roofing can be a significant line item on a construction budget. A solid estimate is the first step to avoid surprises, stay on schedule, and keep the project within budget.
Below is a practical step‑by‑step guide, a sample cost table, and a quick example of how to put everything together.
1. Gather the Essentials
| What to Collect | Why It Matters |
|---|---|
| Roof type & pitch (flat, low‑sloped, pitched) | Determines material choice, labor difficulty, and drainage requirements |
| Roof area (in square metres) | Core quantity needed for all calculations |
| Structural condition | Existing deck/structure may need reinforcement or replacement |
| Building regulations & BCA guidelines | Ensure compliance with fire, fire‑resistance, and safety standards |
| Site constraints | Wind load, height restrictions, access for equipment |
| Cost of permits/inspection | Some municipalities charge for roof work or require a licensed contractor |
2. Break Down the Cost Components
| Cost Category | Typical Items | Typical Cost Ranges (Singapore) |
|---|---|---|
| Materials | • Membrane (EPDM, TPO, bitumen, metal, composite) • Fasteners (screws, rivets) • Waterproofing sealants • Flashing, gutters, downpipes |
$/m² for EPDM/TPO $/m² for composite/metal |
| Labor | • Deck preparation (cleaning, repair) • Membrane installation (laying, fastening, sealing) • Ventilation, insulation, fixtures |
$30 – $50/m² (flat) $/m² (pitched/steep) |
| Structural reinforcement | • Steel beams, timber, concrete patch | $/m² (variable by load) |
| Ventilation & Insulation | • Ridge vents, air vents, insulation boards | $/m² |
| Accessories & Finish | • Metal flashing, downpipes, guttering, roof lights | $/m² |
| Permits & Inspection Fees | • Building & Construction Authority (BCA) inspection | $ (flat fee, variable) |
| Contingency (10–15 %) | For unexpected conditions, material price changes | $/m² |
Tip: Singapore’s BCA Green Mark incentives can reduce overall cost if you opt for high‑performance, energy‑efficient roofing.
3. Calculate the Base Estimate
Determine Roof Area
Flat roof: simply square metres of plan area.
Pitched roof: factor in slope (e.g., 30° gives ~1.15× area).Select Material
Choose based on durability, fire rating, and budget. EPDM/TPO are common for flat roofs; composite or metal for pitched with high wind loads.Apply Unit Costs
Multiply area by material, labor, and other unit costs.Add Structural & Ventilation Costs
Add per‑m² figures for any reinforcement or insulation needed.Include Permits & Inspection Fees
Add flat fee or per‑m² component if the inspection cost scales with size.Apply Contingency
Add 10–15 % of the subtotal to cover unforeseen issues.
4. Build a Simple Estimate Sheet
| Item | Unit | Qty | Unit Cost (SGD) | Total (SGD) |
|---|---|---|---|---|
| Materials | ||||
| EPDM Membrane | m² | 200 | ||
| Fasteners & Sealant | m² | |||
| Labor | ||||
| Deck Prep | m² | 200 | ||
| Membrane Install | m² | |||
| Structural | ||||
| Deck Reinforcement | m² | 200 | ||
| Ventilation | ||||
| Ventilation & Insulation | m² | 200 | ||
| Accessories | ||||
| Flashing & Downpipes | m² | 200 | ||
| Permits & Inspection | ||||
| BCA Inspection Fee | flat | 1 | ||
| Subtotal | **** | |||
| Contingency (12 %) | **** | |||
| Grand Total | **** |
Note: Numbers above are illustrative. Your actual figure will vary based on site conditions, chosen material, and contractor rates.
5. Validate with Multiple Contractors
- Ask for detailed quotes: Should mirror the above breakdown.
- Compare not just price: Check warranties, installation timelines, and after‑sales service.
- Verify BCA compliance: Singapore’s BCA requires that roof installations meet fire‑resistance and building‑strength standards.
6. Keep Track of the Final Estimate
- Store all calculations in a spreadsheet or BIM software.
- Attach photos of the roof, structural drawings, and any regulatory documents.
- Document any assumptions or risk factors (e.g., “heavy rain expected during installation”).
Quick Example: 30 m² Flat Roof on a 3‑storey commercial building
| Item | Qty | Unit Cost | Total |
|---|---|---|---|
| EPDM membrane | 30 m² | $ | $ |
| Fasteners & Sealant | 30 m² | $ | $ |
| Labor (prep + install) | 30 m² | $ | $ |
| Structural reinforcement | 30 m² | $ | $ |
| Ventilation & Insulation | 30 m² | $ | $ |
| Flashing & accessories | 30 m² | $ | $ |
| BCA inspection fee | 1 | $ | $ |
| Subtotal | $ | ||
| Contingency (12 %) | $ | ||
| Total Estimate | $ |
Result: Roughly $per m² for a small flat roof. In practice, larger roofs benefit from economies of scale, but the per‑m² cost often stays within the $ range for high‑quality EPDM/TPO installations.
Final Checklist
| ✔️ | Item |
|---|---|
| ✔️ Confirm roof type & pitch | |
| ✔️ Measure accurate roof area | |
| ✔️ Inspect structural deck | |
| ✔️ Select material (EPDM/TPO/composite) | |
| ✔️ Estimate materials, labor, reinforcement, ventilation, accessories | |
| ✔️ Add BCA permits & inspections | |
| ✔️ Include 10–15 % contingency | |
| ✔️ Get at least three contractor quotes | |
| ✔️ Verify compliance with BCA and HDB (if applicable) | |
| ✔️ Document assumptions & risk factors |
With this systematic approach, you’ll produce a reliable cost estimate that helps you stay on budget, negotiate effectively, and deliver a safe, durable roof for your Singapore property. Happy estimating!