Metal Roofing used as Diaphragm
Metal Roofing used as Diaphragm
(OP)
I am designing a non-insulated building where standing seam metal roofing is specified. Is a structural sheathing substrate (i.e. plywood or cdx) my only option for developing the roof as a diaphragm, or are there standing seam metal roof products rated to provide shear resistance required for diaphragm design? I am aware that the National Frame Builders Association has developed the "1996 Diaphragm Test" which serves to show the acceptable use of light gage metal roofing and siding as lateral force resistance systems for their specific configurations. However, the structure I am designing is not a post frame structure, and I do not want to extrapolate data just to make this work. An alternative option would be to know if there is a steel deck product available that functions as a roofing finish and provides equivalent water intrusion protection as standing seam metal roofing. In this case I could design the diaphragm as per Steel Deck Institute diaphragm design manual.
Any advice is appreciated.
Any advice is appreciated.






RE: Metal Roofing used as Diaphragm
But it would be nice to hear different.
RE: Metal Roofing used as Diaphragm
Personally, I would rely on the CDX and forget the standing seam.
Mike McCann
MMC Engineering
RE: Metal Roofing used as Diaphragm
What type of panel spans are you dealing with? Is thermal expansion the primary concern with slotting of screw holes causing a leak? Or is the general installation where over/underrunning of screws leads to leaks?
RE: Metal Roofing used as Diaphragm
If you need diaphragm, consider plywood or corrugated decking with standing seam applied to top.
RE: Metal Roofing used as Diaphragm
RE: Metal Roofing used as Diaphragm
RE: Metal Roofing used as Diaphragm
Then they decided to do a bit of fatigue work and the found that the purlin spacing had to decrease significantly because the sheeting once it reached plastic fatigue (I don't really know what to call it) lost a lot of its capacity. Hence really wasn't worth the effort for any building which used purlins, but the little garage sheds use this to their advantage, but I believe stramit or lysart did some further private testing to ensure compliance.
Arguing with an engineer is like wrestling with a pig in mud. After a while you realize that them like it
RE: Metal Roofing used as Diaphragm
RE: Metal Roofing used as Diaphragm
RE: Metal Roofing used as Diaphragm
RE: Metal Roofing used as Diaphragm
Depending on the size of the building, one or two bays in each direction should do it.