Green Roofs Extensive and intensive flat green roof structures 1
Definition Green roof structure is such a roof structure on which vegetation planted and where the load bearing structures, the roof insulations, and the horticultural layers creating together an integrated organic system. It needs the co-operative operative works of building constructors and gardeners 2
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History of green roofs Not a new invention: Appears almost every time and everywhere Roof gardens and terraces were established first in the Middle-East Hanging gardens planted terraces supported by arches and columns 4
History of green roofs Other movements: The number of plants increased Development of cities: Le Corbusier in his theoretical works considered roof gardens as essential living spaces for people of future cities Ecological and urban design aspects spreading of extensive structures 5
Benefits of green goofs Living space: New living space for some plants and animals Pleasent and calming view and good feeling Soften the rigid box-like character 6
Benefits of green goofs Microclimate: Water evaporation and oxigen production impoves local microclimate Evaporation controls air temperature Oxigen production purifies the contaminated air Dust bindig effect 7
Benefits of green goofs Technical advantages: Peak load on the drainage system is decreased Temperature changes of waterproof membrane is reduced Serves as thermal insulation Sound reduction 8
Benefits of green goofs Economical aspects: Due to the extended living space, better microclimate and other technical advantages the green roof structures increases the value of the individual flats and the local area. 9
Grouping of green roofs What kind of green roofs are exists? 10
Size 11
Age 12
Formation 13
Function 14
Shape 15
Maintanence 16
Intensive & extensive roof Intensiv the garden is planned considering the functional demand Extensiv the main aspect to match with the local conditions, ecological capabilities 17
Green roof types Extensiv vs. intensiv green roofs 18
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Extensive green roofs Not intended for regular use The thin layer of soil with draughtresistant plants over the load-bearing structure The thickness of soil layer is generally less than 20 cm Maintenance free Technical details Usage Maintenance Watering Weight (superstructure) Thickness Non-passable Low Usually not applied 1,6-2,4 kn/m2 10-20cm 20
Intensive green roofs Contain thicker roof soil layer and allow full utilisation The soil layer is suitable for holding plants of various species and space demand The thickness of soil layer is generally more than 30 cm Continuous and careful cultivation, watering Below 10 to prevent erosion Technical details Usage Maintenance Watering Weight (superstructure) Thickness Full utilisation Continious Required 2-15 kn/m2 30-100 cm 21
Layer sequences Conventional roofs Inverted roofs Dual insulated roofs 22
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Conventional roofs Sequence of roof insulation layers: Water proof membrane Thermal insulation Vapour barier 24
Conventional roofs Vapour barrier must be installed to reduce vapour penetration into the insulation Vulnerable for internal moisture effects Should be avoided in case of new roofs, for re-roofing is acceptable if the existing layers are appropriate form every aspects Sequence of roof insulation layers: Water proof membrane Thermal insulation Vapour barier 25
Inverted roofs Sequence of roof insulation layers: Thermal insulation Water proof membrane 26
Inverted roofs Vapour barrier is not necessary Thermal insulation layer should be resistant against every outside effect (extruded polystyrene, glass foams) Suitable heat-storage t capacity of the structure below the water proof membrane is required (specific surface density of at least 250 kg/m2) The mass above the insulation must be sufficient to prevent floating of the insulation Sequence of roof insulation layers: Thermal insulation Water proof membrane 27
DUAL insulated roofs Sequence of roof insulation layers: Thermal insulation Water proof membrane Thermal insulation Vapour barier 28
DUAL insulated roofs Vapour barrier is not necessary, but careful vapour diffusion planning is needed considering the different thermal insulation materials If old roof insulation are renovated and green roof with double thermal insulation i is constructed the originally built in insulation layer (if suitable) will form the lower thermal insulation layer and this structure can include also the original vapour barrier. Sequence of roof insulation layers: Thermal insulation Water proof membrane Thermal insulation Vapour barier 29
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Structural layers Conventional roofs Inverted roofs Dual insulated roofs 31
Load-bearing structure (2) No special requirement Massive structure are most suitable Load bearing capacity and rigidity (deformity) of the roof deck are very important parameters Vegetation Shrubs and plants with tree stem up to 150 cm Shrubs and plants with tree stem up to 300 cm Shrubs and plants with low tree stem Load kn/m2 0,20 0,30 0.10 Shrubs, grass, original lawn, ground 0.03-0.0503-0 05 cover Soil 8-13 Gravel filling 18 Drainage 8-20 32
Sloping layer (3) A layer to provide slope for the water proof membrane is placed above the load-bearing structure is necessary Layer should be made from gravel concrete if possible The required slope of the screed (and the water proof membrane) is a minimum of 2% on the roof surface and at least 1,5% in roof valleys. 33
Vapour barrier (4) A vapour barrier layer can be aluminium foil with a thickness of at least 0.1 mm which is generally produced in laminated form (e.g. combined with bituminous sheets). Application of vapour retarding layer (e.g. plastic foil) can only be suitable if the vapour diffusion resistance of the water-proof membrane is low (e.g. in case of some soft PVC insulation layers) 34
Thermal insulation (5) Conventional roof structures: Any insulating maretial which has load carrying capacity Inverted roofs: Extruded polystyrene foam boards with T&G edges to eleiminate thermal bridges Laid only in one layer Dual insulated roofs: The upper thermal insulation layer is preferably may be extruded or expanded polystyrene y drainage tray 35
Separating, protecting layer (6) Most cases is a plastic (e.g. polypropylene), film or felt Function: surface equalization (that is protection of the vulnerable membrane from mechanical impact) separation of the base and the insulation (if they are incompatible chemically). separation of the insulation and the membrane if they are incompatible chemically (e.g. in case of polystyrene foam insulation and PVC membrane). 36
Water proofing layer (7) Any kind of water proofing material can be accepted: bituminous sheets, PVC or EPDM membranes Must be root-resistant (material and connections) 37
Protecting layer against roots (8) generally large sized polypropylene or soft PVC foils (foil sheets) are used extremely large (50...100 cm wide) overlapping or laying of double layers are necessary root barriers should be carried up to the height of the edges of the water proofing 38
Water holding & draining layer (9) Function: holding, retarding and storing of water necessary for the vegetation quick draining of surplus water from the structure ventilation of the green roof superstructure Materials: Drain fillings prepared from round river gravels Porous plant-trays Die-pressing formed Plastic trays Drainage trays made of thermal insulation materials 39
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Filtering-protecting layer (10) This layer stops that fine soil or nutrient particles being washed into the water reservoir (drainage) layer from the roof soil and would reduce its water permeability. Non-rotting plastic textile or felt are used 41
Designing guidelines Fire protection Roof drains Wall flashing 42
Fire protection Researchers found that purely theoretically a green roof fire can occur if: the planted vegetation or the wild growing grass are dried to an extent that following a self-ignition total burning up of the whole surface can occur (as at railway embankments). roof soil containing organic material is vulnerable to flaming (such fires can easily become open fires). 43
Fire protection - requirements Boundary walls and fire walls and firebreaks should be constructed at distances not more than 40 m, with a height of at least 30 cm above the ground level. 44
Fire protection - requirements If there is no special fire protection requirement relating to the building, a separation between fire sections of the roof can be created from concrete panels or rough gravel filling with a width of 100 cm. 45
Fire protection - requirements In front of roof superstructures and roof openings (e.g. roof windows, roof lights, etc.) no planted zone covered with inorganic, not flammable materials should be formed with a width of at least 50 cm (e.g. concrete panels, rough gravel filling, etc.) 46
Roof drains Water drainage of green roofs takes place at least two, and in certain cases three planes: Water proofing membrane Top of the thermal insulation On the roof /vegetation surface Roof sumps should allow their control and cleaning control box should be placed 47
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Wall flashings Water proofing should be carried up over the ground surface at least 15 cm on the parapet walls Ventilation of drainage layer should be provided along the wall edge gravel filling parapet walls should be covered box gutters along the superstructure may be placed Safety railing system necessary on used roofs to protect falling accidents 51
Virtual house http://www.diademroof.com 52
Solanova project 53
Dunaújváros Ground floor: shops and services I-VII. floors: 42 flats Building height: 23 m 54
Solanova project Aim: to reach the low energy consumption level (<50 kwh/m2,year) 55
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Extensive green roofs 60
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300 250 Wh/m2a 200 150-84% k 100 50 0 Before Megújuló energia Fosszilis energia SOLANOVA 70