The ROOFMATE MinK system
Allowing for rainwater cooling requires at least 20% increase in insulation thickness. This can be reduced to below 2% by use of the ROOFMATE™ MK separating layer together with ROOFMATE SL (see Agrément certificate 97/3431 - the ROOFMATE MinK system). ROOFMATE MK is waterproof, but at the same time water vapour permeable. It replaces the usual separating layer laid between the insulation and ballast (see Figure 07). Rainwater is prevented from reaching the waterproofing layer, thereby almost completely eliminating the rainwater cooling effect.
ROOFMATE MK should be loose-laid over the insulation, at right angles to the slope with 300mm laps running down the slope . This will allow the ballast, 20/40 aggregate, to counter board flotation to be reduced to 50 mm. At upstands and penetrations ROOFMATE MK should be turned up to finish above the surface of the ballast.
ROOFMATE MK is a spun bonded polyethylene geotextile with the following properties:
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water vapour permeable.
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water resistant.
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tear resistant.
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UV stable - can be left exposed outdoors for up to four months.
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fire - melts and shrinks away from a heat source (unclassifiable as regards Building Regulations).
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temperature - retains flexibility and toughness down to -73°C, melting point is 135°C.
