10/14/2011<< Back to Facilities Management Press Releases Home
Lightweight Structural Concrete Advisory issued by Midwest Roofing Contractors Association
GLENVIEW, Ill. - The Midwest Roofing Contractors Association (MRCA) Technical and Research Committee recently issued an advisory bulletin detailing the switch from normal weight concrete on cast in place roof desks to structural light weight which contain excess water in the light weight aggregate. This can have devastating effects on a newly placed roofing system in terms of uncontrolled moisture gain.
With the switch, the weight savings is considerable while the structural properties are similar. Normal weight aggregate concrete has a nominal density of 150 pounds per cubic foot while structured lightweight can range from 90-120 pounds per cubic foot. In addition, energy savings are achieved by reducing transport costs, handling and weight. All of these features help fulfill the industry's green build initiatives. The lightweight aggregate is ponded in water prior to batching at the plant. Tests have shown it may take upwards of 180 days to dry down. The bulletin describes the consequences to the roof system.
According to MRCA president-elect Randy Adams, R. Adams Roofing, Indianapolis, IN, the association is committed to educating its members and the industry on important issues. "The MRCA Technical and Research Committee dedicates a lot of time to deliberative discussions about industry issues and concerns," says Adams. "When important roofing issues can be distilled into an informative industry improvement bulletin, the MRCA believes it's important to publish that information in a timely manner."
For a complete report which provides critical information regarding roofs and floors as well as new roof installation tips: http://www.mrca.org/files/public/TR_BULLETIN_1-2011.pdf