Costs: Metal roofing claddings | Features

Specification options
	Capital costs £/m2	Net present value for 60 years £/m2	Decision to repaint (years)
Aluminium
Self-supporting roof covering to BS EN 608-2; standing seam.
Aluminium sheet minimum thickness 0.7 mm
Mill finished	24	33	Natural finish
PVC (Plastisol) coating, 200 microns nominal thickness	35	61	Oct-25
PVDF or PVF2 (Polyvinylidene fluoride) coating, minimum 25 microns nominal thickness	33	67	Oct-15
Polyester-based coating, minimum 25 microns nominal thickness	30	67	5-Oct
Mild Steel
Self-supporting roof covering to BS EN 608-1; through fixed. Mild steel sheet minimum thickness 0.7 mm; hot-dip galvanized to BS EN 10142 or BS EN 10147; 275 g/m2 zinc coating weight
PVC (Plastisol) coating, 200 microns nominal thickness	23	59	Oct-25
PVDF or PVF2 (Polyvinylidene fluoride) coating, minimum 25 microns nominal thickness	21	65	Oct-15
Polyester-based coating, minimum 25 microns nominal thickness	18	63	5-Oct
Table notes
Costs include cleaning, maintenance, recoating and replacement. Cost and work frequencies are generic and for roof coverings only, based on a simple 1000 m2 roof plan. Repainting is modelled at an average of the range given. Through fixed roofs are modelled on a design life of 30 years, standing seam with a design life of 60 years.
Whole-life costs vary depending on spans, roof plan, complete roof assembly as well as energy considerations.
Best value can be determined from a whole-life assessment of roofing options that satisfy project-specific criteria. This is particularly important where the whole life cost model is sensitive to small changes such as replacement periods.
A discount rate of 3.5% is used to calculate net present values.