3600sf refoof for existin sfd. If a re-roof project is proposed, the following specifications apply. Existing roofing material comp proposed roofing material comp manufacturer owen corning brand and model tru def duration color (if cool roof required) sierra gray built-up roofing assembly system number per attached listing report (if applicable) specific exemption from cool roof requirements (if applicable) c. Z 7 required building inspector field verification (if applicable) note self-certification by a licensed contractor is acceptable if a signed letter on company letterhead is provided to the building inspector.