The cost of installing a new roof depends on some factors. The cost of installing a new roof will vary from roof to roof. However, the cost you can assume is as follows:
$50 to $80 per m2 for metal roofing
$30 to $80 per m2 for concrete roofing
$180 to $520 per m2 for slate roofing
$68 to $120 per m2 for terracotta roofing
For more information, please refer to this Roof Restoration Cost.