Fire protection systems and life safety

Passive fire protection, the rated walls, floors and enclosures covered in Lesson 6, holds fire back. Active fire protection detects, warns, controls and helps fight it. The building code decides which active systems a building must have: fire alarm and detection, automatic sprinklers, standpipes, fire department connections, smoke control, emergency power, voice communication and elevator recall. Referenced standards then govern how each system is designed, installed and tested. This lesson explains when each system is required, how the code and standards share the work, and what construction managers must coordinate to have the systems accepted before occupancy.

HSE-105 Fire Safety and Emergency Preparedness covers the fire code, fire prevention and the use of fire protection systems once a building is occupied. This lesson focuses on the building code requirements for new construction and on the construction manager's role in delivering them.

A layered approach

Life safety in modern buildings depends on several layers working together. Detection and alarm give early warning so that occupants can leave while conditions are survivable. Sprinklers control or extinguish most fires while they are small, limiting heat and smoke. Compartmentation keeps fire and smoke out of exits and other compartments. Exits give a protected route out. Standpipes, fire department connections, access routes and firefighter elevators allow the fire service to attack the fire. Emergency power keeps the critical systems running. Because no single layer is perfect, codes require redundancy: an unsprinklered building needs more compartmentation, and a high building needs more of everything.

Fire alarm and detection

IBC Section 907 requires fire alarm and detection systems based on occupancy and occupant load, for example in Group A with an occupant load of 300 or more, Group B with 500 or more total or more than 100 above or below the lowest level of exit discharge, Group E with more than 50 occupants, all Group I occupancies and Group R-1 and R-2 above stated sizes. Systems are designed, installed and tested to NFPA 72, the National Fire Alarm and Signaling Code, and most must be monitored by an approved supervising station. Smoke alarms are required in dwelling and sleeping units. Assembly occupancies over 1,000 and high-rises need an emergency voice/alarm communication system, and high-rises need a fire command center.

Fire alarm systems involve many trades and many interfaces: detectors and pull stations, notification appliances (horns, strobes and speakers), connections to sprinkler flow and tamper switches, elevator recall, door hold-open releases, fan shutdown and smoke control, kitchen hood suppression and the monitoring connection. Each interface must be tested. Late design changes, ceiling changes that move devices, and incomplete programming are common causes of delayed occupancy.

Automatic sprinklers

IBC Section 903 requires automatic sprinklers based on occupancy and fire area, for example in Group A-2 fire areas over 5,000 ft² or with an occupant load of 100 or more, Group E fire areas over 12,000 ft², Group F-1 and M fire areas over 12,000 ft² or three stories, all Group H, I and R occupancies (R-3 and townhouses often under the IRC, where state adoption varies), Group S-1 fire areas over 12,000 ft², and buildings with an occupied floor 55 ft or more above fire department access. Systems are designed to NFPA 13, with NFPA 13R permitted for residential buildings up to four stories and 60 ft and NFPA 13D for one- and two-family dwellings. Sprinkler valves must be supervised and connected to the fire alarm or a supervising station.

Sprinkler design depends on hazard classification of the contents, from light hazard (offices, apartments) through ordinary hazard (stores, light manufacturing) to extra hazard and specialized storage protection for high-piled storage. A change in the owner's storage plans, such as racking that reaches higher than the design assumed, can make an approved sprinkler design inadequate. Construction managers should confirm the storage height and commodity class with the owner before the sprinkler design is finalized and again before occupancy.

Standpipes, fire department connections and access

Standpipe systems provide fire fighters with water outlets in stairways and on floors. IBC Section 905 requires Class I standpipes in buildings where the floor level of the highest story is more than 30 ft above the lowest level of fire department vehicle access, or the lowest story is more than 30 ft below the highest level of access, and in other specific cases, designed to NFPA 14. Fire department connections must be accessible and located as approved by the fire code official. The IFC requires fire apparatus access roads within 150 ft of all portions of the exterior walls of the first story, at least 20 ft wide with 13 ft 6 in vertical clearance and designed for the weight of fire apparatus, and fire hydrants within stated distances.

Construction managers often deal with fire department access during site planning and construction. Access roads must be in place, with hydrants working, before combustible construction proceeds far, and fire codes require temporary standpipes in buildings under construction once they reach a stated height. Snow storage, laydown areas, site trailers and fences must not block hydrants, fire department connections or access roads.

Smoke control, emergency power and elevators

Smoke kills more people in fires than flames. Large and complex buildings need systems that keep smoke out of exits and refuge areas or remove it from large spaces. Stair pressurization fans keep exit stairs clear in high buildings. Atriums and other interconnected floor spaces need smoke exhaust to keep smoke above occupants. Elevator hoistways may need pressurization or smoke curtains at their doors.

The IBC requires smoke control systems for atriums, underground buildings and some other spaces under Section 909, which includes design methods, special inspection and acceptance testing. High-rise buildings need standby and emergency power under Section 403.4.8 and Chapter 27, using generators designed to NFPA 110, smoke-proof enclosures or pressurized stairways for some exits, fire service access elevators in buildings over 120 ft and occupant evacuation elevators where chosen. Elevators must recall on alarm under ASME A17.1.

Smoke control and emergency power systems require integrated testing, often called whole-building or integrated systems testing, to show that the fire alarm, fans, dampers, doors, elevators and generators respond correctly together. These tests must be planned, scripted and witnessed, and they often take weeks. Construction managers should schedule them as their own activities, with time for corrections and retests, and with all trades and authorities available.

Special suppression and portable extinguishers

Some hazards need suppression systems other than sprinklers. Commercial kitchen hoods need wet chemical systems designed to NFPA 17A and installed with the hood under NFPA 96. Computer rooms, archives and some electrical rooms may use clean agent systems designed to NFPA 2001, with room integrity testing to show that the agent will be held long enough. Flammable liquid storage may need foam systems. Portable fire extinguishers are required in most buildings, sized and spaced according to NFPA 10, and are usually supplied by the contractor before occupancy. These systems are typically installed by specialist contractors and have their own approvals.

Acceptance testing and documentation

Fire protection systems are not complete when installed. Each must be tested, inspected and accepted before the building is occupied, and the documentation becomes part of the building's permanent record. Typical acceptance steps include:

• Sprinkler and standpipe hydrostatic tests at 1,380 kPa (200 psi) for two hours, flushing of underground mains, main drain and flow tests, and the installer's material and test certificates.
• Fire alarm verification of every device and function, with a verification report or record of completion and the programming documented.
• Fire pump acceptance test with the manufacturer's representative, plotting the pump curve against the design.
• Smoke control and integrated systems testing, witnessed by the authorities.
• Emergency generator load bank testing and transfer switch testing.
• Kitchen hood suppression and clean agent system acceptance tests and room integrity tests.
• Delivery of as-built drawings, operating and maintenance manuals and training for the owner's staff.

In the US, NFPA 4, Standard for Integrated Fire Protection and Life Safety System Testing, sets out integrated testing where adopted or specified, and NFPA 3 covers commissioning of fire protection systems. The fire code official usually witnesses acceptance tests and approves the systems before a certificate of occupancy is issued.

During construction, temporary fire protection deserves the same attention as the permanent systems. Fire codes require fire extinguishers on each floor and near hot work, a fire safety plan for the site, controls on hot work and smoking, and, in taller buildings, standpipes that are kept operational as the structure rises. Combustible construction, especially light wood frame and mass timber before encapsulation, is most vulnerable to fire before the sprinklers are working, and several large losses have occurred at that stage. Site security, hot work permits and early activation of sprinkler zones are the construction manager's main tools.