Productivity and pricing
Erection programme and price from pieces per day
- where
- erection days
- number of pieces
- pieces per hook per day
- direct cost (£)
- gang cost per day (£)
- crane cost per day (£)
- price before VAT (£)
- overheads and profit (%)
- price per tonne (£/t)
- tonnage (t)
Explain this equation
Estimates erection days on site and a price from the number of pieces and daily costs. Use it when pricing a frame or planning crane hire.
N is the number of pieces to lift and r_p how many your gang erects per hook per day. D is the number of days, rounded up. C_g and C_k are the daily costs of the gang and the crane. C_e is the direct cost, m_k the markup for overheads and profit, P_r the price and P_t the price per tonne over a tonnage T.
Erection time is driven by the number of lifts, so days are pieces divided by daily output, rounded up to whole days. Cost is days times daily cost, and the markup is added as a percentage.
Sense check: 250 pieces at about 39 a day is seven days; at £2350 a day that is about £16,500 before markup.
Watch out: light frames with many small pieces cost much more per tonne than heavy frames. Allow for weather and bolting-up after the crane leaves.
Days on site and an erection price from the piece count, your expected lifts per day and daily gang and crane costs.
Enter your values to see the result.
Good to know
Erection time on frames is driven by the number of lifts more than tonnage: SCI reports an average of about 39 pieces lifted and placed per hook per shift on multi-storey work, with peaks around 60. Small bracing, purlins and rails go much faster; heavy trusses, awkward access, wind standing time and bolting-up go slower. Use your own records where you have them. Add separate items for delivery, MEWP hire if not in the gang rate, and bolting/plumbing after the crane leaves.
Common mistake
Pricing on tonnage alone, which badly undercosts light frames with many small pieces.
Limits
Rough programme and price. Weather downtime, multi-crane working and phased access are not included.
Sources
- SteelConstruction.info: Construction – erection (average 39 pieces lifted and placed per hook per shift, peak 60; about 100 t per week with a single hook)
- BCSA: A guide to the erection of multi-storey buildings (Publication 42/06), and BCSA erection guidance on method statements and stability
- BS 5531:1988 Code of practice for safety in erecting structural frames
Results are calculations from the published methods and figures shown, and depend on the data you enter. Always work to the engineer’s drawings and bending schedules, BS 8666, BS EN 1992, BS EN 1090-2, BS 5531/the BCSA National Structural Steelwork Specification and manufacturers’ data. Lifting must be planned under LOLER by a competent person.