Chris is correct. Appendix A does not account for thermal bridging of transitions or penetrations (nails, clips, etc.); it only accounts for thermal bridging from framing, for example, steel studs. There is currently a working group within 90.1 that is working on incorporating the effect of thermal bridging into the standard.

Rahul

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Rahul Athalye
Energy Research Engineer
Pacific Northwest National Laboratory
509-372-4297