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TOPIC: General Discussion

Foam Backer Rods for Oil Canning??

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I am in the process of having a Standing Seam 24 guage Galvalume roof installed, approx 22" flat field, doulble locked. We have paused work after one section of the roof was done because of Oil Canning. I am doing some research now and talking to people involved with roofing to try to get ideas of how to improve it. I've searched and found posts on this website and elsewhere from other people with the same issue. I have found several suggestions to use foam backer rods, maybe 5/8" in center of panel, attached to roof with one nail at bottom, one at top, stretched so that it is tight enough to stay straight. Can anyone who has used this method offer any further suggestions, or can you tell me about your experiences trying this or other methods for reducing oil canning. I have attached several photos of roof, you can see that the oil canning always or usually starts from the right seam and goes toward the middle of panel. These panels are attached to roof on the left side. Thanks for any input!
Guest User

11/24/2007
Photo 2
Guest User

11/24/2007
Photo 3
Guest User

11/24/2007
You didn't say if the panels are being rolled on site or in a plant but either way, you need to inspect the panel closely before it is installed. Place it on a flat surface like a driveway and see if you have the same oil canning. If you do then I would think the roll former needs some adjusting. It could be some bad coil, but the manufacturers have good standards and quality control, but something could have gotten by. Looking at your pictures, I really believe that it is the machine needing some work on one set of rollers. [email protected]
Guest User

11/25/2007
Wade, they are rolled on-site. I think the machine is made by Rollformer Corporation. I will try to put a panel on a flat surface to view, I will have to create a flat surface, none exist here...will let you know. I'll take a picture if there's anything to see. Thanks!
Guest User

11/25/2007
Wade, I put a few of the panels on the flatest surface I could find - a hardwood floor, which may not be perfectly flat but not bad. There is a very small amount of oil canning, you can see a few very small bubbles starting on one side, always starting on the same side. It is much less pronounced as when on roof. And, it isn't enough to really show on a picture, it looks flat in picture I took. Now, I was curious to see if a foam backer rod would get rid of the small amount of oil canning I was seeing with the panel laid out on the floor. I had a 5/8" inch rod and put that under the center of the panel. It got rid of ALL visible oil canning. This rod seemed to be too big as it made a visable crown when you held both edges of the panel down. I would have liked to try a smaller size. So, if I do this on the roof, I'll first try a smaller rod, like 3/8" and see if that helps. What do you think of the less than perfect flatness on the floor - is some imperfection to be expected or should you see it lay totally flat with no issues whatsoever?
Guest User

11/26/2007
Wavey, Email me and I'll try to help you out. [email protected]
Guest User

11/26/2007
Thanks Wade for talking that over with me. I am still interested in talking with anyone who has used the foam backer rods. What size rods did you use - 5/8" 1/2" ? Did it help much? Thanks
Guest User

11/28/2007
We recommend backer rod to relieve oil canning. It crowns the panel in the center. This stretches out the material. I am concerned by the panel width and type combo. What is the seam height? 1"? The panel is too wide for that seam height. I supply 3" tall panels at 22" wide and still have oil canning present in a smooth panel. It may take two beads of backer rod to function on that width panel. If there is no going back, this is probably the only way to move forward. Do they offer striations? Can they refeed the panels through the machine to add them?
Brian Selig
Architectural Building Components Metal Roof and Wall Panels

11/28/2007
Thanks for your reply Brian. Here is what I can tell you: about 21 1/2" wide, 1" double locked seam. The panels in the photo are about 19 1/2' long. We will have this leanth and about 26' long panels. I have asked about stirations but the machine can not do that profile. About going back...we are where we are, and by far the best way to finish the job will be to nail down the best design to reduce oil canning and move forward. If the results are good, we may remove what has been done so far and reinstall it with foam backer rods. Basically, the contractor has made it my responsibility to find the best solution and spell it out for him in detail. I have thought about 2 rods myself, it seems like it might result in a less crowned look. I experimented with (1) 5/8" rod under a panel laid out on the floor. It got rid of the small amount of oil canning visible in the uninstalled panel, but made quite a crown. The bottom line is I'm looking for "Tried and True" designs as I have to know what size rod to use, I've heard 5/8" from several people but one fellow said experiment with rods between 3/8" and 3/4" Also, do you use rods with adhesive or nail top and bottom of rod to roof? Do you have a source for the rods you use. Any diagram or other information that will allow us to use a proven design would be a big help as I think I only get one shot at this! Thank you very much, Wavey
Guest User

12/1/2007
...so, the design I have is very simple, does anyone have anything to add to this, or any experience using the same or similar design?? 1. Try to get adhesive backed rods, 2. Attach adhesive strip of rod to bottom side of each panel, running vertically up the center of the panel 3. Lay and seam the panel same as usual. Size - Start with 3/8" rod, if not all oil canning is removed, try 1/2" rod, then 5/8" my email is [email protected] thanks! Wavey...
Guest User

12/3/2007
I don't know if backer rods help oil canning, you better find some jobs that have this
Guest User

12/26/2007
It depends a lot upon the exact cause of the oilcanning but, yes, backer rods can often help. Oilcanning in essence occurs when excess metal exists in comparison to what is needed for a flat plane. The backer rod can create a hump in the panel to help take up that excess metal. Todd Miller
Todd Miller
Isaiah Industries, Inc.

12/30/2007
Thanks for the reply Todd. I wonder if you have had any experience with a "before and after" situation where backer rods reduced the oil canning seen on a roof? What size rods have you used? Any other tips or ideas on installing these, or any other ideas to reduce oil canning? All I can say about the quality of the roll forming of panels is I laid several of these panels out on the flattest surface available, a hard wood floor (not really all that flat in my case) and saw just the slightest amount of oil canning starting, possible due to floor, maybe slight imperfections in roll forming, etc. However, taking that as a real world example of a pretty good site formed panel... once I put a backer rod under the center of panels, the small amount of oil canning went away, was overwelmed by the new (too big) hump in the panel from the backer rod, of course these panels weren't attached so the hump would be big. I'm hoping to see the same effect on the roof. Any further ideas or details would be appreciated! thanks, Wavey
Guest User

1/5/2008
I have seen 3/8" diameter backer rod work very well. Todd Miller
Todd Miller
Isaiah Industries, Inc.

1/5/2008
That's what we'll start with, thanks!
Guest User

1/5/2008
The roof has been finished for a while, here's a little follow up on what happened. The installer agreed to try foam backer rods on an area of the roof which was not yet installed. We tried 1/2" rod on one panel, and 3/8" rods on two panels as a test, one rod down the center of each panel. All three of these panels looked excellent with no oil canning, so we decided to continue that side of the roof with 3/8" rod. We did still get some oil canning on some of this roof, but less than in the original area done with no foam rods. We pulled off the worst looking panels in the original area and re-did them with new panels over foam rods. Again, improved the look with some large stretches of the roof showing no oil canning, moderate oil canning elsewhere. Conclusion - the foam rods helped - also you're better off if the installer is considering oil canning as he installs, I noticed he was able to "bang out" some of the oil canning by hammering at the seams in some stategic places. Make sure Reducing oil canning is a concern of your installer - not just you. Look at a lot of the roofs they've done - Ask them what they will do to reduce oil canning - do they have a plan? Also...some of the places where I still have significant oil canning seem to be the areas of the roof where the vertical plane is not flat - that is, there is a dip between the bottom of roof and the top ridge of roof. We probably would have had better results if I had made it a priority for the carpenters doing structural work for the new roof deck to shim, etc. to make the roof plane flat, bottom to top. Finally, the last thing that seems to cause oil canning is where the seam between two panels is complex. For example, where there is a skylight, multiple pieces of metal meet and we get wrinkles. I am no expert on this - one roof under my belt - hopefully that will be it!
Wavey Roof

5/26/2008
Thanks for the bounceback. Todd Miller
Todd Miller
Isaiah Industries, Inc.

5/29/2008
I did a job with 29 ga 16" o.c. with a 3/8" backer rod attached to the back of the panel with duct tape. We had had some problems with other jobs and I read about this remedy in a metal roofing magazine. It worked in reducing the oil canning very well without be noticeable from the graound ie. causing a noticeable hump. You do want to start it approx 2' from each end of the panel.
Guest User

12/9/2008
Thanks. Todd Miller
Todd Miller
Isaiah Industries, Inc.

12/12/2008