In the rib? In the flats? Ford or Chevy?

Nick Moore
8/25/2010
Many many people discuss this question daily. Should I screw my panel in the rib or in the flats? And why? Let's hear some opinions and make sure you back them up!
Ken Buchinger
NCI Building Systems, Inc.
8/26/2010
This argument is primarily due to the use of lead headed nails used back in the old days. Because they did not completely seal the hole in the panels, you had to put them up out of the water flow. These days, with fasteners with neoprene washers, you can fasten the panel in the flat where they are slightly less obtrusive. You don't say what type of panel you are using. If you are using a panel with a tall rib, you run the risk of overtightening the fastener and colapsing the rib. Also, when the fastener is in a rib, it can experience more prying action as there in not much to keep it straight. Engineers do not like to see fasteners installed in this manner. Now if you are looking at a 5V Crimp panel as is often used in Florida, many people put the fasteners in the top of the V instead of in the flat. While it is common, it makes no sense to me. While the prying action is not as bad as in a tall rib panel, you have a much harder time getting a fastener started in the top of the V (some folks turn the stack upside down and predrill them, others hit the top of the V with a hammer at the fastener location to flatten it out a little). In this instance, imagine what you are doing to the neoprene washer as the fastener tightens and rubs and catches on the V. In the commercial industry, we use the same type of screws (the heads and washers are the same) on roofs that are up to 800' from eave to ridge at a 1/4:12 roof slope. That means the fastener heads are submerged in even a light rain. We do not have a problem with fasteners leaking (as long as they are properly installed. The bottom line: people successfully do it both ways but you have a lot less chance of a problem and better uplift resistance if you put them in the flat.
Guest User
8/26/2010
Question:I am under contract to buy a house with a pitched corrugated metal roof. As a further point of description, the edge of the corrugation looks like a sine wave. The steel panels were screwed in at the bottom of the "sine wave" curve. This I assume is considered "the flat". Our home inspector said the roof was installed incorrectly because of the screw placement. What causes me concern is that he indicated the screw seals have broken down and there were signs of water leakage. The inspector attributed this to the placement of the screws. In your opinion, is the inspector's conclusion credible or could the seal deterioration and subsequent water leakage really be a warranty issue do to an incompetent installation relating to other than the screw placement? The house is five years old and located in Santa Fe, NM. What other comments might you have on this roof as I have described it?
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