Although there is a long list of benefits, there are two things to consider:

  1. Heavier structure
    Installing a green roof puts extra weight on the structure. In most cases, the supporting structure is sufficient for the installation of a green roof.
  2. Cost
    Purchasing a green roof is a non-negligible factor, but green roofs are more cost-effective in the long run. For example, you do not need to invest in an (expensive) drainage system, green roofs reduce temperature fluctuations (thermal insulation) and dampen noise (sound insulation), finally, green roofs make your roof cover last longer by protecting it from UV rays and hail, among other things.