The owners of the Algo Centre Mall in Elliot Lake, Ontario, are wishing right about now that they hadn't ignored those roof leaks. A large section of the mall's roof collapsed

, killing two women and injuring 22 other people. That's a harsh lesson for waiting to reroof - a fact that roofers may want to remind some building owners who are still sitting out the economic recovery.

Of course, most roof collapses have more to do with the structure than the roofing. This is certainly the case in the number of reports of buildings collapsing under heavy snow loads in the Midwest and Canada this past week. However, there is one case last week of a structural collapse that roofers should pay close attention to: Building owner, Aquascape, has sued a Wisconsin-based firm and numerous subcontractors for $13 million in damages after a part of the company's vegetative roof collapsed. No one was injured during the collapse at the company's headquarters, but the damages caused workers to have to relocate for a year while the roof was fixed. The lesson here for roofers: Be sure the building is sound before roofing. That may sound obvious, but a lawsuit is not, and the increased loads that a vegetative roof adds may not be so obvious to the owners.