Wind uplift for Roofing

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Author Message Kenneth C. Crocco Senior Member Username: kcrocco Post Number: 88 Registered: 04-2003 Posted on Wednesday, March 14, 2007 - 05:41 pm:    Assuming one does not specify FM for non-FM insured buildings. (There are reasons for this assumption, but for this thread it is just an assumption.) How would you specify wind up lift requirements for roofing? Considering SPRI and ASCE 7 as options, who does the engineering/analysis to determine roof uplift loads, field, edge, and corner? Who determins loads for edge flashing? How is this all working for you. We just heard from an FM engineer, it looks from their perspective that specifying roof uplift requirements for the most part (present company excepted) is not working well. Installation of roofing is not working well either. I would appreciate any thoughts on the subject. thank you. Ralph Liebing, RA, CSI Senior Member Username: rliebing Post Number: 562 Registered: 02-2003 Posted on Thursday, March 15, 2007 - 07:10 am:    We require the roof warranty to include everything from the deck up. In that, it is the roofing manufacturer who is to establish and detail all the engineering/analysis required. Have heard FM will be revising their recent changes. Jerome J. Lazar, RA, CCS, CSI, SCIP Senior Member Username: lazarcitec Post Number: 335 Registered: 05-2003 Posted on Thursday, March 15, 2007 - 12:49 pm:    Kenneth In South Florida, there are two directions, either obtain design pressures from a company like RWDI that performs a wind tunnel test on the building model or have the Structural Engineer prepare calculations based on ASCE 7. Wayne Yancey Senior Member Username: wyancey Post Number: 320 Registered: 05-2005 Posted on Thursday, March 15, 2007 - 02:29 pm:    For further reading on this subject, see Professional Roofing March 2007 for article titled "Understanding wind-resistant design." Wayne Yancey Senior Member Username: wyancey Post Number: 321 Registered: 05-2005 Posted on Thursday, March 15, 2007 - 02:30 pm:    For futher reading on this subject, March 2007 issue of Professional Roofing has an article titled "Understanding Wind-resistant Design." John Bunzick, CCS, CCCA Senior Member Username: bunzick Post Number: 677 Registered: 03-2002 Posted on Thursday, March 15, 2007 - 04:29 pm:    I have used ASCE 7 to do the wind uplift calculations myself. Depending on the building configuration it's not that hard to do. The simplified procedure is the basis for the NRCA's on-line wind uplift calculator (which I have read about but not yet used.) The article Wayne refers to is a good overview. Richard Howard, AIA CSI CCS LEED-AP Senior Member Username: rick_howard Post Number: 122 Registered: 07-2003 Posted on Thursday, March 15, 2007 - 04:59 pm:    I have the benefit of several structural engineers sitting in adjacent cubicles. They do wind analysis on every structure they design and share their calcs. Just make sure you don't use their result for maximum (corner) uplift as the basis of your basic (field) uplift number or you will inadvertently double the load. Like John, I use ASCE 7 to do my own calculations and agree that it is not rocket science. I have also tried NRCA's calculator and it is easy and painless and seems to get the same results. I found out a long time ago that when talking with a PE, it helps to understand the calculations he/she uses. My biggest problem is getting my architects to stop slapping an FM 1-90 roof on everything. They all seem to think the 90 stands for 90 mph instead of 90 psf. Anonymous   Posted on Saturday, March 17, 2007 - 04:52 pm:    IBC 2003 adds a requirement for edge metal flashings (gravel stop, fascia and copings), except gutters, for low-slope membrane roof systems to be designed according to ANSI/SPRI ES-1, "Wind Design Guide for Edge Systems Used with Low Slope Roofing Systems," to resist buildings' basic design wind speeds. Previously, IBC had no specific requirements for edge metal flashings. Interested to hear how this has affected specifications for shop bent metal edge systems. July 2006 Construction Specifier "Vulnerability at the Roof's Edge..." Tom Thomas E. Momeyer, AIA, CCS Ronald L. Geren, RA, CSI, CCS, CCCA, SCIP Senior Member Username: specman Post Number: 425 Registered: 03-2003 Posted on Saturday, March 17, 2007 - 08:55 pm:    Tom: Check out this discussion we had about 6 months ago: http://discus.4specs.com/discus/messages/1828/2706.html Thomas E. Momeyer, AIA, CCS Junior Member Username: tmomeyer Post Number: 2 Registered: 03-2007 Posted on Sunday, March 18, 2007 - 12:48 pm:    Ronald, Thanks for pointing out the previous discussion. I added to that discussion, but noticed that it didn't show up when you go to Product Discussions. I'm not familiar with how these discussions work. Since the discussion took place 6 months ago, my added comment may be "lost" over there? Joanne Rodriguez, CSI, CDT, LEED AP Senior Member Username: joanne Post Number: 51 Registered: 09-2004 Posted on Monday, March 19, 2007 - 04:19 pm:    Ken you can specify for wind uplift by using all of this and then some. The "then some" is through ASTM testing standards as well as UL test methods. I know that UL is commonly thought of for just fire but they also affect wind. The seven tests that FM uses to obtain class 1 rating in roofing frequently cross over to ASTM and UL.