Final answer:
According to NFPA 72, smoke detectors on peaked roofs should be placed within 3 feet horizontally of the peak to ensure timely smoke detection, while adhering to local codes and manufacturer instructions.
Step-by-step explanation:
The question pertains to the placement of detectors in relation to the peak of a roof, which is a topic often covered by building safety codes and regulations that are integral to the field of engineering. Specifically, the query asks within how many feet horizontally of the peak should detectors be first spaced and located. According to the guidelines of the National Fire Protection Association (NFPA), specifically NFPA 72, which covers the National Fire Alarm and Signaling Code, smoke detectors in a room with a peaked roof should be located within 3 feet (0.9 meters) horizontally of the peak.
The reason for this requirement is that smoke rises to the highest point, and placing detectors too close to the peak can delay detection because of a potential dead air space right at the apex. However, it is crucial to consult the latest edition of the NFPA codes or any local regulations that might supersede this general rule as specifics can vary depending on the jurisdiction and the edition of the codes being enforced. Always ensure that all installations meet both local codes and manufacturer instructions.