Green Roof Soil Depth

The structural engineer must factor in the weight of completely saturated soil since the plantings and the soil will hold a significant amount of water.

Green roof soil depth. Extensive green roofs usually use plants with foliage from 2 to 6 inches and from 2 to 4 inches of soil. Its soil depth is a full 2 inches enough to support many low growing succulents and a limited number of accent plants. This is especially true of intensive green roofs which can have soil that is two feet deep or more. Careful plant selection and maintenance is needed to ensure annuals do not become weeds on a green roof.

These require irrigation and a substrate depth of at least 200 mm. The lite system is typically used on retrofit projects when the roof is engineered with only 15 to 17 pounds per sf for the green roof component. When sedum vegetation is applied to a green roof the weight is approximately 30 kg m2. It is generally not recommended for hot climates.

An intensive green roof is intended to be more of a natural landscape installed on a rooftop. The planting medium in extensive green roofs ranges from 1 6 to 6 inches deep and while deeper systems have been installed they are not favored as much as the shallower systems drought tolerant sedums succulent plants and grasses are the typical plants used since they are shallow rooted and use little water plant diversity on these roofs is kept low to simplify care and to be sure all plants have similar moisture requirements. Sports turf requires a designed soil or growing medium to ensure effective drainage and a substrate. Careful species selection is needed to ensure outcomes can be met.

Some green roofs are constructed specifically to support sports turf. Intensive green roofs may use plants with foliage from 1 to 15 feet and may require several feet of soil depth. Intensive roofs which are thicker with a minimum depth of 12 8 cm 5 1 16 in and can support a wider variety of plants but are heavier and require more maintenance and extensive roofs which are shallow ranging in depth from 2 cm 13 16 in to 12 7 cm 5 in lighter than intensive green roofs and require minimal maintenance. The surface and play requirements are much more demanding than for amenity turf.

It is also important to factor in the type and lifetime of the roof membranethat will be used. Rooftop trees rooftop trees are a special category of deep intensive systems. There are two types of green roof.