Green Roof Dead Loads

The values for dead loads in table 3 2 are for commonly used materials and constructions in light frame residential buildings.

Green roof dead loads. Roof shall balance drainage and water retention to meet drainage requirements but retain as much rain as possible while still meeting drainage and maximum wet weight dead load requirements. Add a conservative snow load allowance for flat roofs of 15 p s f and the design criteria can easily exceed 70 p s f. Astm e2397 is the established standard procedure for determining the dead and live loads associated with green roof systems. The venny green roof has shallow substrates on two types of roof the first roof is on shipping containers and is designed for a dead load of 250kg m 2 and live load of 100kg m 2.

The long term performance of green roofs depends on many factors. Green roof shall provide suitable drainage and water retention capacity to support healthy vegetation cover according to specified vegetation performance. The second trussed roof is designed for a dead load of 160kg m 2 and a live load of 40kg m 2. Of living roof construction this could translate to 175 000 pounds of dead load on the roof top.

The dead load of a green roof assembly should be determined on a project specific basis because growth medium composition varies from job to job. D dead load l live load l r live roof load w wind load s snow load e earthquake load r rainwater load or ice water load t effect of material temperature h hydraulic loads from soil f hydraulic loads from fluids. We can provide more information on individual products or systems on request. Green roofs typically use lightweight engineered soils with very light drainage and insulation layers.

The use of reliable and established products that comply with green roofing guidelines is important. For a modest building using 2500 sq ft. 3 3 dead loads dead loads consist of the permanent construction material loads comprising the roof floor wall and foundation systems including claddings finishes and fixed equipment. Soil does not necessarily occupy the full depth of the assembly.

The second most common conservative assumption found in the industry is to assume that the green roof is a soil load rather than a dead load.