Construction details
4 Green roof 3
4.1 Roof edge without overhang • Extensive planting • Waterproofing below insulation • Liquid waterproofing
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On green roofs it is advisable to place the waterproofing below the insulation where it is protected against mechanical damage. Liquid waterproofing materials may not contain any solvents when laid on a timber loadbearing structure. When selecting the drainage layer and the substrate, it is vital to ensure that there is sufficient ballast to prevent the drainage layer from lifting; it may even be necessary to use “grasscrete” paving blocks. The filter fleece should extend at least to the top of the drainage layer if the drainage layer is in the form of a loose fill material.
4.2 Roof edge with overhang • Extensive planting • Waterproofing above insulation • Bitumen waterproofing
As the vapour barrier must be welded, a separating membrane is necessary between the edge-fixed timber roof elements and the vapour barrier. The desire to leave a timber parapet exposed conflicts with the regulations and guidelines for metal roof coverings, which call for a 15 cm high skirting of waterproofing alongside any component rising above roof level. This detail does not comply with this requirement because the overhang is relatively small and the sheet metal finish falls to the outside.
4.1
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Planting Substrate Filter fleece Drainage layer Filter fleece Extruded polystyrene (XPS) board Liquid waterproofing Edge-fixed timber roof element Loose gravel Parapet capping Sheet metal clip Liquid waterproofing Extruded polystyrene (XPS) board Clamping bar Sheet metal skirting Planting Substrate Filter fleece Drainage layer Protective membrane
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Bitumen waterproofing, 2-ply Rigid plastic foam board Vapour barrier Separating membrane Edge-fixed timber roof element Parapet capping Sheet metal clip Bitumen waterproofing, 2-ply Rigid plastic foam board Parapet, glued laminated timber Sheet metal finish Protective membrane Timber battens Edge-fixed timber roof element Bridging plate
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4.2