Structural Loadings

The structural loading of a living roof needs to be considered at the design stage.  Worth noting is that many flat roof structures with ballast or paving slabs, may be able to be replaced with an extensive green roof system with no structural loading implications.  The following table details the saturated weights of different green roofs and landscape elements:

Indicative Structural Loading for Various Types of Roof

Roof type                                                 Loading

Gravel surface                                          90-150 kg/m2

Paving slabs                                             160-220 kg/m2

Vehicle surface                                        From 550 kg/m2

Extensive green roof (sedum mat)            60-150 kg/m2

Extensive green roof (substrate based)    80-150 kg/m2

Intensive green roof                                200-500 kg/m2

Note: loads are fully saturated  


Source: Living Roofs and Walls, Technical Report: Supporting London Plan Policy, Greater London Authority, 2008