Metal prices have gone through the roof – which means the cost of your copper covering is sky-high. So which material is best value? Alex Smith reports, Davis Langdon crunches the numbers
In the Past six months there have been substantial increases in metal prices, which could have a knock-on effect on the costs of metal roofing. The global economic recovery has fuelled the increase in the price of raw materials. Demand in China in particular has been huge and is causing considerable shortages. The increase in average cash buyer prices recorded by the London Metal Exchange illustrates this (see left).

The large rise in copper prices have also been caused by production problems at the world's largest copper mines in Indonesia and Chile and world stockpiles of copper have fallen by more than 40% over the past year. In fact, copper prices are at their highest for eight years and analysts expect prices to continue to rise during 2004. Lead prices continued to rise during February 2004 and prices have doubled between the start of 2003 and mid-February 2004.

The current prices of metal roofing compared with other roofing methods are shown below. The table contains indicative inclusive rates for types of roofing, representing average contract rates in February 2004. Ranges reflect the complexity of the roof, detailed specification and regional price differences. Rates are based on slope (not plan) area.

Whole-life roofing costs
In July 2003, cost consultant Davis Langdon & Everest published a study on the comparison of roofing costs. This is an update to an original study carried out by DL in 1995, commissioned by the International Copper Association and the Copper Roofing Advisory Service. However, specifers should bear in mind the recent price rises in metal discussed above when assessing whole-life costs.

Data was collected from the RICS' ºÃÉ«ÏÈÉúTV Cost Information Service for typical roof costs in £/m2 for a variety of building types to analyse the cost sensitivity for increases in cladding costs and how adjustments in the rate affect the overall building rate. It can be seen that an increase to the roofing cost of £1/m2 adds about 0.1% to the overall building cost.

The table above shows the national average rates for roof elements only, on a selection of building types. Rates are based on plan area for the roof.

Lifecycle costs
The table below illustrates a simple model for calculating and analysing lifetime costs over a 60-year period. The methodology used here is different from the 1995 study to reflect the increase in data now available. Expectancy periods were still discussed with contractors, but this was only to reinforce the published data available.

Maintenance data, similarly, has been taken from published data and from discussions with specialist roofing contractors.

Lifecycle costs were projected for 60 years as this is a number, which sources have tended to use as a reference. However, it should be noted that several roof coverings – including copper, stainless steel, lead and slate – have life expectancies well in excess of this period.

Methodology

This cost exercise was primarily compiled using DLE’s extensive national cost database, professional judgment and discussions with specialist contractors. Additional data was obtained from the ºÃÉ«ÏÈÉúTV Cost Information Service (BCIS); Spon’s Architects’ and Builders’ Price Book 2003; the London Metal Exchange and the DTI. Construction rates were extracted for both metal and non-metal roof coverings and entered into a simple spreadsheet, average rates for all roof finishes were then derived. In the 1995 study, specialist roofing contractors were asked for their opinion on the life expectancy of typical metal roofs. This study has used published data from sources such as the PSA and the Housing Association Property Manual which produce detailed life expectancy and maintenance costs for building materials. As in the 1995 study, the costs have been based on an L-shaped single storey development with a 30-degree pitched roof and stepped ridge, with a floor area of 450 m2.

Related files/tables

Roofing