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Table notes

• Costs relate to the covering material; the substrate has been excluded.
• Costs include initial supply and installation; removal and replacement at end of service life.
• Maintenance is not included or costed.
• Costs are discounted to net present values at a discount rate of 3.5%. European standards cover fully supported roof products for pitched roofs BS EN 501 – zinc; 502 – stainless steel; and 504 – copper. These standards define material qualities, tolerances, coatings, finishes and quality assurance, generally by reference to other standards.
• Only the more commonly used fully supported roof covering materials are included in the lifetime cost assessment. Ferritic stainless steels, aluminium alloys, mild steel sheet coverings and metals with coatings, for example, are excluded.

• For further guidance on factors affecting durability and modes of failure of fully supported metal roofs see www.building.co.uk.
• BPG have completed a research project on behalf of ºÚ¶´ÉçÇø LifePlans (BLP) for the Housing Corporation to make available durability data on the internet.
• The BLP Construction Durability Database includes durability data for over 800 fabric and services component check out www.componentlife.com.
• For further information, contact Alan Swabey – costing research, or Peter Mayer– technical research, at ºÚ¶´ÉçÇø Performance Group on 020 7583 9502 or email: p.mayer@bpg-uk.com.