STRUCTURAL ELEMENTS AND BUILDING METHODS 465 GREEN ROOFS
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1 roof planting structure (intensive): approx 20 cm intensive substrate filter course/mat approx. 6 cm drainage course 2 steel band in point foundation (C12/15) 3 wooden terrace structure: wooden planks fastened with V2/A torx screws beam course stiffening plank point foundation with post supports, support base (galvanized with fin) protective layer under point foundation 4 superstructure (waterproof concrete roof): roof seal (root-proof) sloping screed reinforced concrete
Fig. 3.14.44: Wood covering at junction with lawn
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OKFF +0.00
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1 paving 2 approx. 3 cm chippings 2/5 3 approx. 20 cm crushed stone 2/32 4 building protection and drainage mat (car type) 5 superstructure (waterproof concrete) roof seal (root-proof) sloping screed reinforced concrete Fig. 3.14.43: Paved surface, able to take weight
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15.0 cm
OKFF -0.03
Fig. 3.14.45: Terrace covering on stilt bearing, door junction
1 interior with threshold 2 steel grating as facade gutter 3 terrace structure: natural stone slabs metal angle as support for cantilever arm cantilever arm in galvanized steel, material approx. 2 mm thick stilt course, adjustable height with joint dividers protective course in stilt course area building protection mat 4 superstructure (warm roof) roof seal (root-proof) sloping thermal insulation (foam glass sheets) vapor seal reinforced concrete
In multi-layer superstructures, the filtration layer filters out sediments, e.g. humus substances, in order to safeguard drainage layer function in the long term. Geotextiles are commonly used. > Figs. 3.14.41 and 3.14.42 The vegetation base layer is where the plants are actually located. It must be structurally stable—i.e. it must not be allowed to sag. Its plant substrate therefore has significantly lower levels of humus. For one-layer extensive green roofs, the FLL guidelines stipulate no more than 4% organic substances. This value can reach 6–12% for multi-layer designs, depending on design and gross density. As for grain size distribution, the allowed percentage of fine-grained sand and clay components is greater for intensive green roofs (max. 20%) than for extensive green roofs (max. 7%). The goal is good permeability together with optimum water retention. Topsoil mixtures with grain size distribution and humus content that meet the above requirements, e.g. which contain a high proportion of sandy soil, can be used for the vegetation base layer. The use of mineral bulk materials such as lava, pumice and expanded slate or recycled substances such as crushed brick with added organic substances and clay is widespread. > Figs. 3.14.43–3.14.45 Hard surfaces and timber decking are often constructed in combination with the plant surfaces, especially in intensive green roofs. This means that the protective layer, and usually the drainage and filtration layers as well, are always continued beneath the hard surface to permit unobstructed water flow. For water accumulation irrigation, however, the drainage layer is interrupted at the accumulation threshold. Paved and tiled surfaces can be laid in chippings directly on protective fleeces or filtration layers. Alternatively, adjustable-height stilt bearings are possible. This allows weight to be reduced, but reduces the loadbearing capacity of the surface. This may have to be balanced out by laying a thicker tiled surface.