The toxic top:  The environmental and structural risks of treated lumber supports on rooftops.

The market has been shifting away from treated wood blocks for rooftop support of pipes, HVAC equipment, and ductwork, etc., largely because they are subject to biodegradation—in other words, rot.  When the sleepers deteriorate, they cause pipe sag and unbalanced HVAC equipment which shortens operational life.  But there are other issues—critical ones---for moving toward other [...]