I thought that 20 minutes credited to the gypsum came "attached"· with the caveat that the wood studs were part of a "system" that included gypsum or a noncombustible sheathing on the walls. Gypsum on each side of the wall (5/8 inch Type X, I am guessing from memory) provided 20 minutes each, and the wall provided the other 20 minutes (I think the stud wall credit was broken down further to even give a rating for the air gap in between the 16 O.C. spacing)
I think the 20-minute credit was more of a mental contruction, than a fact in action. Will open stud walls (albeit packed with mineral wool) but not protected by gyspum, offer the same 20 (or at least 15) minutes as a alternative "system" when exposed to an ASTM E-199 temperature curve? I would not sign an Engineering Judgment for such an alternative system. This seems to be what Todd is essentially looking for: An engineering judgment for an alternative FRR "system"·. Depending upon how the shower enclosure burns (Class II commodity or slower), I would sign off on a document that states the tub/enclosure, and the mineral wool/wood stud "system" provide an equivalency to a 15-minute FRR. Most plastic tub/shower enclosures, however, burn too quickly to pass even this test, is my guess. Note also that if the LSC is invoked, many new occupancies require the sprinkler inside the bathroom, regardless of the exception. Despite how difficult it may be to meet the prescriptive Code section in this thread, is this situation on a performance basis, really so dangerous to life? I think not. scot deal excelsior fire _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
