Structural loadings and wind uplift

Most roof deck constructions are suitable for some form of green roof provided that they can support the dead and imposed load, though intensive green roofs should only be constructed on concrete decks.

Dead and imposed loads - should be calculated in accordance with BS EN 1991-1-1, BE EN 1991-1-3 and BS EN 1991-1 4 and should include the weight of the waterproofing system, saturated weight of the green roof components and substrate, vegetation, snow loads, and imposed loads such as access by people and vehicles as well as point loads for items such as water features and trees.

Sheer forces - need to be taken into consideration generally on roof pitches in excess of 10 degrees, though this depends on the levels of substrate being installed and the vegetation used. Anti-shear measures should suit the individual system and on a Bauder sedum blanket system this comprises a simple mechanical retention strip with spikes that hold the blanket onto the waterproofing.

Our technical team can provide information and advice so relevant data can be passed to the structural engineer.

Wind Uplift and Erosion

The need for stability of the system is increased because the negative pressure forces that can develop during high wind conditions are counteracted by the weight of the green roof system. Wind can also lead to erosion problems on exposed sites, especially if plant establishment is in the early stages.