To get the optimal performance of an inverted roof some basic rules must be followed:
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The roof-deck should be preferably a min. 150-200 kg/m2 reinforced concrete slab, having min. 1.5% slope. In case of lightweight roof structures (eg. metal decks), the thermal resistance of the layers below the waterproofing membrane must be min. R= 0.15 m2 K/W.
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Build-up over the ROOFMATE™ SL-A boards should be diffusion-open. Standing water and paving slabs laid directly on the insulation causes condensation risk. In roof gardens, terraces, parking decks a diffusion layer (eg. 3-5 cm gravel, crushed gravel) is recommended between the thermal insulation and the soil, pavers or concrete slab covering.
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ROOFMATE SL-A boards should be installed in single layer.
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Thickness of the ballast layer should be determined upon preventing wind-uplift and floating of the boards. For non-accessible roofs min. 50 mm 16/32 mm washed gravel is recommended.
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A diffusion-open, not water absorbent geotextile, laid with 200 mm overlaps between the ROOFMATE SL-A boards and gravel layer, improves the stability against flotation, protects the skin of the insulation boards and helps to prevent gravel to penetrate the joints between the boards. The use of 110-140 g/m2 non-woven polypropylene fleece is recommended for this purpose.
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The edge zones of the ballast layer must be protected against the increased wind effects with additional ballast, paving slabs or ballast retainers.
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