Five-Story Hotel Proposed With NFPA 13R
A design-build team submits a preliminary plan for a new five-story, 90,000 ft² hotel of Type III-A construction. The highest occupied floor is 64 ft above grade; the roof is 72 ft. The architect proposes an NFPA 13R system because the building is residential and the corridors, guest rooms, and lobby can be protected without a full NFPA 13 system. The local fire official notes that the building has a combustible attic, an elevator machine room, and a commercial kitchen on the first floor. The owner wants to avoid the cost of a full NFPA 13 system and asks whether the 13R approach can be approved if the building is fully sprinklered and has smoke detection. The project is in Michigan and will be reviewed under the adopted building and fire codes.
1. May the designer use NFPA 13R? Explain the governing limits and identify the standard that applies.
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NFPA 13R is not available here. Its scope limits the system to buildings that are four stories or fewer above grade plane and not more than 60 ft in height above grade plane. This building is five stories and 64 ft to the highest occupied floor, so it exceeds both limits. Smoke detection, full coverage, and a residential occupancy do not waive the scope limits, and a local fire official cannot approve a 13R design outside its listing. The design must be an NFPA 13 system, with the applicable density/area, hose allowance, and protection of spaces that 13R may omit. The Michigan adopted building and fire code enforces the referenced NFPA standard; the plan reviewer should comment that the design basis must be changed before approval.
2. If NFPA 13 is required, identify at least three design features that change from the 13R proposal and explain why.
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Changes include: (1) Concealed combustible spaces and the attic must be evaluated under NFPA 13; 13R omissions do not automatically carry over. (2) Elevator machine rooms, electrical and mechanical rooms, and storage areas must be protected unless a specific NFPA 13 omission applies. (3) Hydraulic calculations must use the NFPA 13 density/area for the occupancy and include the full hose allowance; the 13R calculation cannot be used. (4) The commercial kitchen may need high-temperature sprinklers and coordination with the hood suppression system. The reviewer should require a room-by-room comparison of omitted areas rather than accepting a blanket note.
3. What should the plan reviewer require before accepting the sprinkler design?
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The reviewer should require a revised design basis statement citing NFPA 13, a complete hydraulic calculation with the correct density/area and hose allowance, and a drawing set showing all protected and omitted spaces. The submittal should identify the attic construction, elevator machine room, kitchen hood area, and any combustible concealed spaces. The reviewer should also verify that the contractor is licensed in Michigan and that the permit application matches the approved plans. Approval should be withheld until the 13R scope error is corrected.