Analysis & loading · Load take-down & combinations
Dead load build-up and design loads calculator
List the layers of a floor or roof build-up, either as a thickness with a unit weight or as an area load directly. The tool totals the dead load, adds the imposed load for the occupancy, forms the ULS combinations, and converts them to line loads on a supporting beam for the tributary width.
Standard: AS/NZS 1170.1 Appendix A unit weights · AS/NZS 1170.0 combinations 1.35G and 1.2G + 1.5Q · line load = area load × tributary width
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Inputs in the worked example
The live calculator starts with these values; change any of them and every result, check and diagram updates instantly.
| Input | Value | Unit |
|---|---|---|
| Layers: item, thickness (mm, 0 = area load), unit weight (kN/m³) or area load (kPa) | Ceramic tiles and bedding, 0, 0.6 Screed, 40, 22 Reinforced concrete slab, 200, 25 Ceiling services and lighting, 0, 0.5 Partition allowance, 0, 1.0 | |
| Imposed (live) load | 3 | kPa |
| Tributary width to the beam | 4 | m |
| Long-term factor ψl | 0.4 |
Worked example — results
| Result | Value | Unit |
|---|---|---|
| Ceramic tiles and bedding | 0.600 | kPa |
| Screed (40 mm × 22 kN/m³) | 0.880 | kPa |
| Reinforced concrete slab (200 mm × 25 kN/m³) | 5.000 | kPa |
| Ceiling services and lighting | 0.500 | kPa |
| Partition allowance | 1.000 | kPa |
| Total dead load G | 7.98 | kPa |
| 1.35G / 1.2G + 1.5Q | 10.77 / 14.08 | kPa |
| Governing ULS area load | 14.08 | kPa |
| ULS line load on the beam | 56.30 | kN/m |
| Short-term service G + 0.7Q line load | 40.32 | kN/m |
| Long-term G + ψlQ line load | 36.72 | kN/m |
Method, formulas and assumptions
- Typical unit weights (AS/NZS 1170.1 App A): reinforced concrete 24–25, screed 22, brickwork 19–20, timber 5–7, steel 77 kN/m³; tiles with bedding ≈ 0.5–0.7 kPa; ceilings and services 0.3–0.5 kPa; partitions per Cl 3.4 or the building layout.
- ULS: 1.35G and 1.2G + 1.5Q; service short-term G + ψsQ (ψs = 0.7 for floors), long-term G + ψlQ.
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For preliminary design and education. Check every result against the current standard and your own engineering judgement before use.