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BUSINESS FEATURE OIL CANNING ROUNDTABLE


coil as the panels are being produced. A striated panel still allows for panel folding and locking onto eaves, valleys, hips and ridges; however, it is a slightly different look than a fl at pan.


During installation …


Lynn: For structural metal panels, the bear- ing surfaces must be properly aligned with the underlying wall or roofi ng. The bearing surfaces also must be properly and evenly spaced. Al- lowances must be made for thermal expansion in all directions. The substrate must be made of a material, or set of materials, which will not adhere to the underside of the metal and restrict the normal thermal movements of the metal.


Tuschall: Panels should not be carried “flat” or lifted by a single corner from a bundle. Fol- low manufacturers handling and installation procedures.


Hance: Proper handling and alignment of support will infl uence appearance. Over-engage- ment of the cladding panel and over-driving of fasteners are two installation related factors, which can contribute to oil canning. Most panels accommodate transverse thermal expansion by fl exing of webs and by "take-up" at sidelaps. When panels are over-engaged, these relief features are hindered or eliminated, particularly for fl at panels without corrugations. Installing the fasteners requires some control to ensure that the fastener is not over-driven. An over-driven fastener will pull down the cladding locally and can create deformations.


Parvin: Careful handling, the use of a “slip sheet” between the metal and underlayment— some underpayments have a surface that acts as a slip sheet and some metals require special underlayment materials—careful attachment


of fasteners. The more the panel is allowed to move, the less likely the impact of oil can- ning. The substrate is often the largest culprit in oil canning. Deck deviation, bows, ridges and camber all induce stress in the fi nished panel installation. The deck substrate needs to be in a level plane. If not shimming or other corrective


the panel in tension to remove the oil canning. Otherwise panel replacement is the solution for extreme cases.


Hance: Very little can be done to eliminate oil canning. For the wall you may be able to create slight outward bow by shimming to put the face in tension but this is not very practical in most instances.


Lynn: Once oil canning occurs, it is very dif- fi cult to remove it. Unless the metal is very thick, in which case oil canning is less likely, fl attening the oil can area is next to impossible. Preven- tion through the proper design, manufacture, handling, fabrication and installation is key to minimizing oil canning.


measures need to be implemented. A careful planned layout and start of roof panel installation is critical. If panels are not started square and plumb the crew tries to over pull or push a series of panels to make adjustment the stress often induces oil canning.


Stermer: Avoid over-driven fasteners. Cor- rect uneven (out of plane) panel support (open framing or solid sheathing). Avoid compressing panel width. Install on the specifi ed module. Me- chanically curve panels, do not “walk down” fl at pan panels in a curved, barrel application. Add expanding tape under the middle of a standing seam panel to force the fl at to pillow upward.


MCN: Once it has occurred, can anything “fi x” an oil-canned metal roof or wall?


Stermer: For fl at pan tongue-and-groove wall panels, the interior supports (not the end supports) can be adjusted out to put the face of


Parvin: If the cause is the design of the method of attachment it may be possible to make adjustments that reduce the metal wavi- ness. If it is a single damaged panel caused by handling or some unrelated impact after installation it can be replaced if the method of attachment permits removing a panel without damaging he adjacent panel. But, generally, oil canning is the sum of the experience of the designer and the skills of the installer and further remedy is difficult at best. Severe and significant oil canning can generally be spotted during product installation with exception to working on cloudy days. It is very difficult and costly to fix an oil canning issue. Therefore, the installation crew should pay attention and report to their company project manager if and when oil canning appears excessive. The term excessive versus industry standard is a very difficult and arbitrary evaluation.


38 METAL CONSTRUCTION NEWS May 2013


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