An interesting application of concrete construction is under review in one of the world's most advanced sustainable construction studies. Students at the British Columbia Institute of Technology's (BCIT) Centre for Advancement of Green Roof Technology (CAGRT) are measuring the performance of various materials for green roof structures.
During the next two years, the students will measure two key roof performance qualities of several 6-ft x 6-ft test structures called Roofing Evaluation Modules (REMs). First, they track the amount and quality of storm-water runoff from the roofs. Second, they record the thermal performance. Most of the REMs are wood-frame structures, but one is made with insulated concrete forms (ICFs).
Quad-Lock, an ICF manufacturer based in Surrey, British Columbia, has supplied wall and roof ICFs for the project. Quad-Deck, a pan-form for suspended concrete floors, is well-suited as a substrate for green roofs.
The system forms one-way T-beam suspended spans that handle live loads of more than 100 lbs/sq ft. Its expanded polystyrene (EPS) panels are supported and reinforced by two integral steel beams molded into the product from end-to-end. The T-beam configuration can reduce a structure's steel consumption by 50%, and its weight by 40%. Shoring requirements are reduced by 50%, compared to hand-set suspended forms. On the flip side, the panels are insulated up to R34, and owner-ready for drywall or a suspended ceiling to be installed.
The concrete decking also addresses leakage, perhaps the biggest concern with green roofs. Concrete resists damage from wet soil and insects, and with the help of crystalline admixtures, provides a waterproof surface.
While the results of CAGRT's study could translate into an increased market share for ICF roofs, the big savings are directed to customers. “We already know there is a 40% – 70% increase in thermal performance for concrete versus wood construction,” says Quad-Lock's Senior Training Consultant Douglas Bennion. “We may be able to add a 25% improvement in the thermal performance of a concrete roof, as well as extending the life of the materials. If we can demonstrate with an engineering study that the amount of water runoff will be reduced, a building's permit impact fees can drop thousands of dollars on a commercial structure, offsetting the cost of installation.”
Keith Miles, owner of Northern Hills Redevelopment, Orange, N.J., has seen another type of savings. His Alpha Lofts feature green roofs for their environmental benefits, as well as much-needed green space on the commuter line to New York City. “Using insulated Quad-Deck panels instead of the traditional ‘stick-built' construction allowed us to find efficiencies, and sharpen our pencils to come up with a better bottom line,” says Miles.
Ken Branyan, owner of Ken's Konstruction, National Park, N.J., agrees. He recently completed the Wat Mongkoltepmunee Buddhist Temple, Bensalem, Pa., where the Quad-Deck green roof covers a 4000-sq-ft terrace. “It allowed us to get the whole job put together quickly,” explains Branyan, “and still give the customer a good quality product.”
Quad-Lock plans to use the BCIT study to educate architects and designers on the sustainable aspects of ICFs, including green roofs. To be sure designers can act on these benefits, Quad-Lock also wants to help educate concrete producers to become green roof experts.
See how Quad-Lock products were used in these green roof projects:
Northern Hills Redevelopment, Orange, NJ
Wat Mongkoltepmunee Buddhist Temple
Ken's Konstruction, National Park, NJ