Issue link: http://digital.canadawide.com/i/1295215
O C T O B E R 2 0 2 0 | 15 Building Envelope P H OTO G R A P H Y + T EC H N I C A L I L LUS T R AT I O N CO U RT E SY H Y D ROT EC H M EM B R A N E CO R P. insulation panel. The membrane imparts resistance to water penetration while being permeable to water vapour. The panel has excellent thermal resistance and sound deadening properties. Matthieu Danis, product manager, wood fibre, for BP Canada, points out that another advantage of his company's products for environmentally- conscious envelope developers is that, "We use locally-sourced post consumer and industrial fibre in all our products, crushed to pulp and then reformed using only paraffin and starch as binders." Also, the by-products from BP's Quebec plant are used by regional farmers as fertilizer. The roof is of course an integral part of the build- ing envelope, and Denis Gingras, national sales director at Hydrotech Membrane Corp., notes that the use of blue roofs in stormwater management in urban areas "is drawing more attention from designers and is an integral part of a global concept of sustainable development called the 'Sponge City.'" Blue roofs address water where it falls – at the rooftop – and is increasingly being considered by developers, with flat roof surfaces providing an ideal capturing resource. Gingras, whose company supplies all the neces- sary components for different types of blue roofs, says, "To start out, a blue roof should include a waterproofing membrane; a seamless membrane designed to withstand a permanent hydrostatic head. Unlike roofing membranes, this type of mem- brane must be suitable for use in fully submerged conditions. In addition, this membrane must be able to be used in a zero-slope roof deck to optimize the blue roof water volume capacity. Hot-applied rub- berized asphalt membrane meets this requirement very well. Its seamless installation and ability to be submerged for very long periods of time make it ideal for the wet conditions in blue roofs and green roofs as well." Water resistant thermal insulation comes next, and Gingras says XPS (eXtruded PolyStyrene type IV) insulation is the best as it does not pick up water. For a protected membrane roof, the water is held in the voids between the aggregates, about 30 to 40 percent of the volume according to the size of the material used. Another blue roof option is a combined green/ blue roof assembly where the water is jointly retained in the growing media and detained in the water storage units installed beneath the growing media and pavers. "This option offers the maximum capture and management of water at the rooftop," Gingras says. "The user never knows that a signifi- cant stormwater management feature is working below the green surface." A Hydrotech's blue roof system.