Section 706.7.2 of the FBC Existing Building Code notes that for HVHZ reroof projects, a secondary water barrier is required by use of 4-6" SA stripping over the plywood deck joints and a 30# felt is required atop that. It also notes that "No additional underlayment shall be required over the top of this [30#] sheet). Note this does not apply to roof slopes < 2:12 or clay/concrete tile roofs. Could you please help explain what this means and what will be required for steep-slope reroofs (non-tile)? Is the 30# felt considered a "water barrier"? And therefore, once the joints are stripped in and the 30# is applied, another water barrier (continuous SA mod bit sheet) would not also be required? Please also confirm that the stripping is not required for the non-HVHZ zones, and that for reroofs and new construction, just a single layer of SA mod bit can be applied direct to the deck? Thank you!