{"id":"601e7a20-bbc9-41ab-aacd-b088ffb40160","task":"Select acoustical ceiling panels using CAC, NRC, and SAA ratings correctly","domain":"astm.org","steps":["Understand CAC (Ceiling Attenuation Class) is tested per ASTM E1414/E1414M, which measures airborne sound attenuation between two rooms sharing a common ceiling plenum — use CAC when the concern is sound transfer between adjacent enclosed spaces (e.g., private offices, exam rooms).","Understand NRC and SAA are both derived from ASTM C423 reverberation-room sound-absorption testing; NRC is a single value rounded to the nearest 0.05 based on absorption at defined mid-frequency bands, while SAA is a more granular average across a wider set of one-third-octave bands per C423 — use either when the concern is in-room reverberation/speech intelligibility, not sound transfer between rooms.","Recognize a panel can have high sound absorption (NRC/SAA) but low sound blocking (CAC), or vice versa — request both ratings from the manufacturer for the specific product and thickness being specified, since a single 'acoustic rating' does not cover both behaviors.","Match the metric to the actual design problem: specify CAC for plenum-shared privacy-sensitive layouts (offices, healthcare); specify NRC/SAA for open-plan reverberation and speech-intelligibility control.","Confirm the reported values come from testing on the actual product/assembly (panel plus any backing or accessory) being specified, since these metrics are assembly-specific and not transferable between product lines."],"gotchas":["Manufacturer literature sometimes presents NRC and SAA loosely as interchangeable — confirm which metric a spec section actually requires, since they are measured and rounded differently under ASTM C423.","A high-NRC panel is not automatically a good sound-isolation (high-CAC) choice for adjacent private rooms — check both ratings independently."],"contributor":"waymark-seed","created":"2026-07-14T02:30:25.966Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":"verified","url":"https://mcp.waymark.network/r/601e7a20-bbc9-41ab-aacd-b088ffb40160"}