Originally Published as: Backer rods
There is little more disturbing to a quality-conscious metal roofing contractor than to see excessive oil canning in a roof he is installing. The customer may have a similar reaction and things can become unprofitable quickly when it happens.
Dan Perkins of Dan Perkins Construction in Ishpeming, Mich., says he and his crews have spent many hours trying to understand and control the appearance of oil canning and have come up with standard practices for minimizing this problem on their jobs.
Some of the basic rules to follow include using 24-gauge steel, panels no more than 18 inches wide, low gloss paint finishes, and minor ribs or striations.
“Nothing in our experience is more effective in minimizing oil canning than using foam backer rod taped to the back of roofing panels,” Perkins says. “This practice puts a continuous crown in the panel forcing the oil canning to the outside edges of the panel.”
The backer rod is 3/8-inch in diameter and costs 3 cents per linear foot. It’s sold at masonry supply houses and typically used in tip-up slab construction. It is taped to the center of the panel ending approximately a foot from either end of the finished panel.
“We now use backer rod on 100 percent of our jobs because of its effectiveness in reducing the appearance of oil canning and making sure it looks acceptable to our clients,” Perkins says.
“We can do certain things to minimize the appearance, but metal will deform slightly while going through its expansion and contraction cycles and inevitably show some form of deflection,” Perkins says. “However, by implementing these techniques we have virtually eliminated complaints due to excessive oil canning.”
Most installers will settle for getting rid of the complaints if they can’t eliminate oil canning.
Any thoughts?
Do you see something you like or would do differently? Got a better way to minimize oil canning? Share it with the editors. Write to Metal Roofing Magazine, PO Box 255, Iola WI 54945 or email [email protected].
