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Specification options
Capital costs £/m2Net present value for 60 years £/m2Decision to repaint (years)
AluminiumÌýÌýÌý
Self-supporting roof covering to BS EN 608-2; standing seam. ÌýÌýÌý
Aluminium sheet minimum thickness 0.7 mmÌýÌýÌý
Mill finished2433Natural finish
PVC (Plastisol) coating, 200 microns nominal thickness3561Oct-25
PVDF or PVF2 (Polyvinylidene fluoride) coating, minimum 25 microns nominal thickness3367Oct-15
Polyester-based coating, minimum 25 microns nominal thickness30675-Oct
Mild SteelÌýÌýÌý
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 weightÌýÌýÌý
PVC (Plastisol) coating, 200 microns nominal thickness2359Oct-25
PVDF or PVF2 (Polyvinylidene fluoride) coating, minimum 25 microns nominal thickness2165Oct-15
Polyester-based coating, minimum 25 microns nominal thickness18635-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.