To mitigate conditions or materials that increase the likelihood of a fire starting or spreading within a building, California's Title 24 building code and related regulations have established a comprehensive approach that covers not only the design and construction of the building itself, but also the systems installed within it.
1. Building Materials and Design: The California Building Code specifies the types of materials that can be used in different parts of the building based on their fire-resistance rating. This rating is a measure of how long the material can withstand a standard fire resistance test without failing. The code also requires the use of certain design features to limit the spread of fire, such as fire walls, fire barriers, and fire partitions. These must be constructed of fire-resistant materials and extend continuously from the foundation to or through the roof. Below are examples of how some of these codes apply to single- and two-family dwellings.
- Fire-Resistant Construction CRC §R302.3 – Construction, projections, openings, and penetrations of exterior walls of dwellings and accessory buildings shall comply with Table R302.1(1); or dwellings and accessory buildings equipped throughout with an automatic sprinkler system installed in accordance with Section R313 shall comply with Table R302.1(2).
- Two-Family Dwellings CRC §R302.3 – Dwelling units in two-family dwellings shall be separated from each other by wall and floor assemblies having not less than a 1-hour fire-resistance rating where tested in accordance with ASTM E119, UL 263 or Section 703.2.2 of the California Building Code (see code section for exceptions).
- Penetration Firestop System CRC §R302.4.1.2 – Penetrations shall be protected by an approved penetration firestop system installed as tested in accordance with ASTM E814 or UL 1479, with a positive pressure differential of not less than 0.01 inch of water (3 Pa) and shall have an F rating of not less than the required fire-resistance rating of the wall or floor-ceiling assembly penetrated.
- Fireblocking CRC §R302.11 – In combustible construction, fireblocking shall be provided to cut off both vertical and horizontal concealed draft openings and to form an effective fire barrier between stories, and between a top story and the roof space (see code section for required fireblocking locations).
- Draftstopping CRC §R302.11 – In combustible construction where there is usable space both above and below the concealed space of a floor-ceiling assembly, draftstops shall be installed so that the area of the concealed space does not exceed 1,000 square feet. Draftstopping shall divide the concealed space into approximately equal areas (see code section for additional requirements).
2. Fire Protection Systems: Fire protection systems are a critical part of building safety. One of the most common types is an automatic sprinkler system, which can suppress a fire in its early stages before it grows and spreads. In addition to sprinkler systems, smoke alarms are required in each sleeping room, outside each separate sleeping area in the immediate vicinity of the bedrooms, and on each additional story of the dwelling, including basements. This ensures that residents are quickly alerted in the event of a fire. The specific requirements for these systems can vary depending on the type of building, its size, and its occupancy. Below are examples of how some of these codes apply to single- and two-family dwellings.
- One and Two-Family Dwellings Automatic Sprinkler Systems CRC §R313.2– An automatic sprinkler system shall be installed in one- and two-family dwellings. The two exceptions are listed below (in addition to the below exceptions, residences permitted via the Alternative Owner-Builder (AOB) ordinance do not need sprinklers).
- An automatic residential fire sprinkler system shall not be required for additions or alterations to existing buildings that are not already provided with an automatic residential sprinkler system.
- Accessory Dwelling Unit, provided that all of the following are met: The unit meets the definition of an Accessory Dwelling Unit as defined in the Government Code Section 65852.2, the existing primary residence does not have automatic fire sprinklers, the accessory detached dwelling unit does not exceed 1,200 square feet in size, and the unit is on the same lot as the primary residence.
- Smoke and CO Alarm Listing CRC §R314.1.1 – Smoke alarms shall be listed in accordance with UL 217. Combination smoke and carbon monoxide alarms shall be listed in accordance with UL 217 and UL 2034.
- Fire Alarm Systems CRC §R314.7 – Fire alarm systems shall be permitted to be used in lieu of smoke alarms and shall comply with Sections R314.7.1 through R314.7.4.
3. Electrical Systems: The California Electrical Code (CEC) establishes stringent standards to prevent electrical fires. Detailed regulations govern proper wiring to prevent overheating and circuit protection devices such as circuit breakers and fuses to ward off overloading. The installation of Ground-Fault and Arc-Fault Circuit Interrupters is required in certain areas to rapidly disrupt power during a fault. Grounding and bonding, which prevent voltage spikes and potential shock hazards, are also crucial components of these regulations. Additionally, rules on appropriate installation of electrical boxes, usage of approved electrical equipment, and stipulated clearance between electrical gear and combustible materials are part of the code. Given the critical nature of these rules and their periodic updates, it's essential to consult with a licensed electrician or your local building department for accurate guidance. Below are examples of how some of these codes apply to single- and two-family dwellings.
- Width of Working Space CEC §110.26(A)(2) – The width of the working space in front of the electrical equipment shall be the width of the equipment or 30 inches, whichever is greater. In all cases, the workspace shall permit at least a 90-degree opening of equipment doors or hinged panels (see code section for additional working space requirements).
- Dwelling Unit Ground-Fault Circuit-Interrupter (GFCI) Protection CEC §210.8(A) – All 125-volt through 250-volt receptacles installed in bathrooms, garages, outdoors, crawl spaces, basements, kitchens, sinks, boathouses, bathtubs, shower stalls, laundry areas, other indoor damp locations, and other wet locations and supplied by single-phase branch circuits rated 150 volts or less to ground shall have ground-fault circuit-interrupter (GFCI) protection for personnel (see code section for exceptions and additional requirements).
- Dwelling Unit Arc-Fault Circuit-Interrupter (AFCI) Protection CEC §210.12(A) – All 120-volt, single-phase, 15- and 20-ampere branch circuits supplying outlets or devices installed in dwelling unit kitchens, family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, laundry areas, or similar rooms or areas shall be AFCI protected (see code section for exceptions and additional requirements).
- Rod Electrode Summary (Article 250) – Rod type electrodes shall not be less than 8 ft in length, shall be stainless steel and copper or zinc coated steel, and shall be at least 5/8 inches in diameter. Additionally, a second rod shall be connected to the first rod by a #6 copper conductor installed in one continuous length without a splice or joint and shall be not less than 6ft from the other rod (see Article 250 for exceptions and additional requirements).
4. Means of Egress: The California Title 24 building code has specific provisions for exits or 'means of egress' in buildings, designed to ensure that people can safely leave a building in the event of a fire or other emergency. Every dwelling unit must have at least one egress door. This is the primary means of exit and entry for occupants and should be easily accessible and operable from the inside without the need for keys or special knowledge. In addition to the egress door, every sleeping room and basement with habitable space should have at least one operable emergency escape and rescue opening. This could be a window or a door leading directly outside. The purpose is to provide an alternative escape route if the primary exit is blocked, and to allow entry for rescuers if needed. Additionally, all means of egress, including exterior exit stairways and ramps, should have illumination to ensure visibility in case of an evacuation. Below are examples of how some of these codes apply to single- and two-family dwellings.
- Means of Egress CRC §R311.1 – Dwellings shall be provided with a means of egress in accordance with this section. The means of egress shall provide a continuous and unobstructed path of vertical and horizontal egress travel from all portions of the dwelling to the required egress door without requiring travel through a garage. The required egress door shall open directly into a public way or to a yard or court that opens to a public way.
- Egress Door CRC §R311.2 – Not less than one egress door shall be provided for each dwelling unit. The egress door shall be side-hinged and shall provide a clear width of not less than 32 inches where measured between the face of the door and the stop, with the door open 90 degrees. The clear height of the door opening shall be not less than 78 inches in height measured from the top of the threshold to the bottom of the stop. Other doors shall not be required to comply with these minimum dimensions. Egress doors shall be readily openable from inside the dwelling without the use of a key or special knowledge or effort.
- Floor Elevations at the Required Egress Door CRC §R311.3.1 – Landings or finished floors at the required egress door shall be not more than 1 ½ inches lower than the top of the threshold.
- Emergency Escape and Rescue Opening Summary (CRC §R310) – Basements, habitable attics and every sleeping room shall have not less than one operable emergency escape and rescue opening that opens directly into a public way. They shall have a net clear opening of not less than 5.7 square feet, a minimum opening height of 24 inches, a minimum opening width of 20 inches, and shall have the bottom of the clear opening not greater than 44 inches measured from the floor. Emergency escape and rescue openings shall be maintained free of any obstructions other than those allowed by this section and shall be operational from the inside of the room without the use of keys, tools or special knowledge.