Green Roof

It is usual to take in to account geotechnical evaluation during lightweight structure or fill design in which soil parameters and load are accounted for each construction project individually. The lightweight designed structure or fill can entirely or partly compensate additional loads on the subgrade. Partial compensation can be used where settlements have largely occurred, the settlement period after construction is relatively short, or controlled settlements can be accepted. Entire compensation eliminates settlement periods altogether.

When the groundwater or surface water level is high, it can be good practice to partially reduce the weight of the fill structure to ease the pressure on the surrounding area. The structure shall be designed with consideration to buoyancy connected with rising water levels within the structure, a particularly relevant factor for Leca® Lightweight Expanded Clay Aggregate structures located in vicinity of a water body or flood area.

Leca® Lightweight Expanded Clay Aggregate fill structures are designed to compensate additional loads produced by a fill structure on a subgrade either entirely or partially. Partial compensation can be used when settlements have mostly happened, the settlement period after construction is relatively short, or controlled settlements can be accepted. Additionally, when groundwater or surface water level is high, it is helpful to partially reduce the weight of the fill structure (limited buoyancy).

When green roofs are used as recreational and more flexible areas, there will often be a need to build slopes and variations in the terrain. Here, solutions with low weight are preferable to reduce the extra load and set limitations for the underlying construction. A well-tested, effective solution is to use Leca® 10-20 mm. Before the Leca® materials are laid out, the final surface level is determined using leveling. The materials can be incorporated with blowing equipment and then covered with geotextiles and reinforcing mesh to stabilize the entire structure. The remaining layers can be designed as with normal extensive or intensive green roofs.

Under footpaths and other areas with traffic, it may be necessary to vibrate lightly with a small plate vibrator. The footpath's final covering can be paving stones or gravel, for example.

Ventilation shafts and other technical installations on the roof can be covered with a layer of Leca® lightweight fill, which will transform the roof area into a lovely, green public area or a private garden

Extensive green roofs are characterized by their low weight due to a limited thickness (typically 5-15 cm for the growing medium) and very special plants, which must be low and hardy, most often alpine, dry soil or succulent plants. Sedum plants are often used. The growing medium, which is typically composed of a mineral mixture of sand, Leca® light aggregate and sphagnum, is designed for the selected plants.

Usually, the plants are watered and fertilized only until they are established. After the first year, maintenance consists of two visits per year for invasive species weeding and safety and membrane inspections.

Intensive green roofs are characterized by their use as a 'garden' in much the same way that people use a garden at ground level. The increased soil depth (20-200 cm) allows for more diverse plants, the use of trees, shrubs and other landscape architectural aspects and thus the development of a more complex ecosystem.

The requirements for maintenance - especially watering - are greater, and irrigation systems are usually prescribed. We recommend construction and gardening expert advice and an experienced contractor.

Leca® lightweight aggregate can be used in the mixture for the growing medium and as an effective drainage layer. Drainage or retention of rainwater can be optimized by using different types of Leca® lightweight aggregate.