Follow fire-rated door hardware constraints when drilling or prepping doors

Steps

1. Before drilling or modifying a fire-rated door or frame, locate the door's permanently affixed label identifying the testing lab, manufacturer, and fire rating, and confirm the door is still within its listed configuration.
2. Follow field-prep limits for fire doors: round holes drilled for hardware are generally capped at a small maximum diameter, with listed exceptions for cylinder holes and for surface-applied hardware installed per both the door and hardware manufacturers' listings.
3. For any modification not clearly covered by an existing listing or exception, contact the door's listing laboratory through the manufacturer for written approval before altering the assembly.
4. Never remove, deface, or obscure the fire-rating label during the work; if a label is missing or illegible, arrange field-labeling through an authorized testing/listing service rather than proceeding without one.
5. Recommend the required annual fire-door assembly inspection if the client doesn't already have one scheduled, since it's a commonly cited compliance gap.