The cost of installing a green roof depends on the roof area, how close you are to the supplier, the type and maturity of plants used and whether the green roof is extensive (not to be walked on as only a thin layer of soil is used) or intensive (a flat roof garden planted on a deep layer of soil). A fully installed extensive green roof is likely to cost £50- 100 per m², while an intensive green roof can be installed for £130-140 per m². For suppliers, visit www.bauder.co.uk, www.urbanroofgardens.co.uk.