CFC · California Fire Code

How must incompatible materials be separated in storage?

If you store hazardous materials in containers larger than 5 lb, larger than 0.5 gal, or any compressed gas, the California Fire Code requires you to keep incompatible materials apart — by **20 feet**, by a **noncombustible partition extending 18 inches above and to the sides**, or by using approved cabinets/enclosures. Do not store incompatibles in the same cabinet or exhausted enclosure; compressed gases have additional cabinet/ventilation limits. See **§ 5003.9.8**, **§ 5003.9.9**, **§ 5003.9.10** for the governing rules.

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Last reviewed: July 6, 2026

What the code requires — 2-4 sentences

The California Fire Code requires that incompatible materials stored in containers larger than 5 pounds (2 kg), 0.5 gallon (2 L) or any amount of compressed gases must be kept apart — either by distance, by isolation with a noncombustible partition, or by approved cabinets/enclosures. The controlling rule is § 5003.9.8 (separation methods), with supporting provisions for shelving and approved containers in § 5003.9.9 and § 5003.9.10. See § 5003.9.8 .

Separation is required when containers are larger than the small-container thresholds (or for any compressed gas): keep incompatibles at least 20 feet apart, isolate them behind a noncombustible partition that extends 18 inches above and to the sides, or store them in the appropriate listed cabinet/enclosure. (Plain English restatement of § 5003.9.8.)

Requirements in detail

When the separation rule applies

  • The separation rule applies when stored materials are in containers with a capacity of more than 5 pounds (2 kg), more than 0.5 gallon (2 L), or for any amount of compressed gases. See § 5003.9.8 .

How to accomplish separation (methods from the code)

  • Segregation by distance: maintain a minimum separation of 20 feet (6096 mm) between incompatible stored materials. See § 5003.9.8 .
  • Isolation by partition: use a noncombustible partition that extends at least 18 inches (457 mm) above and to the sides of the stored materials. See § 5003.9.8 .
  • Approved cabinets / enclosures:
    • Liquid and solid hazardous materials may be stored in hazardous material storage cabinets (when permitted method). See § 5003.9.8 and construction/marking details in § 5003.8.7 .
    • Compressed gases must be in gas cabinets or exhausted enclosures in accordance with § 5003.8.5 and § 5003.8.6 (ventilation and cabinet limits). See § 5003.9.8 and related gas cabinet requirements in § 5003.8.6.2 and § 5003.8.6.3 .
  • The code explicitly states: Materials that are incompatible shall not be stored within the same cabinet or exhausted enclosure. See § 5003.9.8 .

Shelving and storage furniture

  • Shelving used for hazardous materials must be substantial, braced and anchored for the applicable seismic design category, and constructed/coated with materials compatible with the stored hazardous materials; shelves used for containers must have a lip or guard. See § 5003.9.9 .
  • Exceptions: storage inside approved hazardous material storage cabinets or laboratory furniture designed for the purpose is allowed, and storage in amounts not requiring a permit per § 5001.5 may be excepted. See § 5003.9.9 .

Safety cans and quantity increases

  • Safety cans listed to UL 30 can be used to increase maximum allowable quantities of flammable/combustible liquids per control area in Table 5003.1.1(1); other listed cans (UL 1313) have different allowances. See § 5003.9.10 .

Decision-relevant dimensions and values

Decision item Value / threshold When it applies Code Reference
Container-size trigger > 5 lb (2 kg) or > 0.5 gal (2 L) or any compressed gas Rule applies when stored containers exceed these sizes § 5003.9.8
Minimum segregation distance 20 ft (6096 mm) Alternative to partition when isolating incompatibles § 5003.9.8
Partition height/side extension ≥ 18 in (457 mm) above and to sides Noncombustible partition option to isolate materials § 5003.9.8
Cabinets for liquids/solids UL-listed hazardous material storage cabinets or built per § 5003.8.7 Use to store liquids/solids safely; incompatibles not allowed in same cabinet § 5003.9.8 and § 5003.8.7
Gas cabinets / exhausted enclosures Cabinets with exhaust ventilation at negative pressure; max 3 cylinders per gas cabinet unless other provision Required for compressed gases § 5003.9.8, § 5003.8.6.2, § 5003.8.6.3
Shelf requirements Seismic bracing, compatible materials, lip/guard on shelves For shelf storage of hazardous materials § 5003.9.9
Safety can listing UL 30 (for quantity increases) or UL 1313 allowances For flammable/combustible liquids and other liquids per listing § 5003.9.10

Exceptions & special cases

  • Containers smaller than or equal to 5 pounds (2 kg) or 0.5 gallon (2 L) are outside the explicit trigger for § 5003.9.8; the code's separation methods are required only where containers exceed those thresholds or for any compressed gas. See § 5003.9.8 .
  • Storage inside approved hazardous material storage cabinets or laboratory furniture designed for the purpose is treated differently — cabinets follow § 5003.8.7 construction/marking requirements and may be used where allowed; however, incompatible materials must never be placed in the same cabinet or exhausted enclosure. See § 5003.8.7 and § 5003.9.8 .
  • For certain specialty materials (for example pyrophoric materials), the code adds more stringent isolation: indoor storage of pyrophoric materials must be isolated by 1-hour fire barriers in addition to § 5003.9.8 methods (unless stored in approved cabinets). See § 6404.1.4 .
  • Where other chapters set material-specific separation distances or configurations (e.g., pyrophorics, water-reactives, flammable solids), those provisions supplement § 5003.9.8 and must be followed. See chapters referenced in the code (examples: Chapter 64, 67, 59). The code cross-references § 5003.9.8 for indoor storage separation in other chapters (for instance § 2704.3.3). See § 2704.3.3 .

If you need an interpretation for a material pair that isn’t listed in a chapter, the fire code official or a technical opinion may be required (see California Building Code authority provisions) — that detail is outside the retrieved snippets. See the California Building Code for authority on interpretations (not fully retrieved here).

Common mistakes

  • Assuming the rule never applies to small containers — the code applies when container size exceeds 5 lb / 0.5 gal or for any compressed gas; small-container exemptions are limited. See § 5003.9.8 .
  • Storing incompatibles together in the same storage cabinet or exhausted enclosure — explicitly prohibited. See § 5003.9.8 .
  • Misreading the partition requirement: the code requires a noncombustible partition extending 18 inches above and to the sides — not a full-height wall — unless another chapter requires more (e.g., 1-hour barrier for pyrophorics). See § 5003.9.8 and § 6404.1.4 .
  • Forgetting the special rules for compressed gases (ventilation, cabinet cylinder limits). See § 5003.8.6.2 and § 5003.8.6.3 .
  • Ignoring shelf construction and seismic anchoring requirements for stored hazardous materials. See § 5003.9.9 .

Worked example — concrete scenario with numbers

Scenario: An R&D lab stores two materials that are incompatible: (A) a corrosive liquid in two 3-gallon containers and (B) an oxidizer in 10-pound (≈4.5 kg) pails.

  1. Do the thresholds trigger separation?

    • Corrosive containers: 3 gal > 0.5 gal — triggers separation rules.
    • Oxidizer pails: 10 lb > 5 lb — triggers separation rules.
      Therefore § 5003.9.8 applies.

  2. What are the compliant options?

    • Option 1 (distance): Keep the corrosive and oxidizer storage areas at least 20 feet (6096 mm) apart. This meets the segregation-by-distance option in § 5003.9.8.
    • Option 2 (partition): Store both in the same room but isolate each pile/bin behind a noncombustible partition that extends 18 inches (457 mm) above and to the sides of the stored items — provided this meets the rest of the facility’s requirements. See § 5003.9.8.
    • Option 3 (cabinet): If either material can be legally and practically stored in an approved hazardous material storage cabinet (constructed/per § 5003.8.7), do so — but do not place the incompatible material inside the same cabinet. See § 5003.8.7 and § 5003.9.8.

  3. Practical selection: If the lab footprint cannot provide 20 ft separation, place each material in its own approved cabinet or create noncombustible partitions around each storage location per § 5003.9.8. If one of the materials is a compressed gas, it must go into a gas cabinet/exhausted enclosure per § 5003.8.5/6.

Related provisions

  • § 5003.9.8 — Separation of incompatible materials (primary rule).
  • § 5003.9.9 — Shelf storage requirements (seismic anchoring, shelf materials, lips/guards).
  • § 5003.9.10 — Safety cans and listing requirements (UL 30, UL 1313).
  • § 5003.8.7 — Hazardous material storage cabinet construction, labeling and liquid-tight bottom.
  • § 5003.8.6.2 / § 5003.8.6.3 — Gas cabinet ventilation and maximum cylinders per cabinet.
  • § 5005.1.1 — Use/handling separation — cross‑references § 5003.9.8.
  • § 2704.3.3 — Indoor storage separation in semiconductor fabrication context — references § 5003.9.8.
  • § 6404.1.4 — Pyrophoric materials: additional isolation (1‑hour fire barriers) beyond § 5003.9.8.

If you need the full text of any of these sections or a site‑specific interpretation (e.g., which materials are incompatible with which), I can pull the exact code text for the listed sections or outline how to prepare a submittal for the fire code official.

Code references

Grounded in the retrieved California Fire Code — click a citation to read the verbatim passage:

  • CFC § 5003.9.3 High relevance — show source text

    5003.9.3 Protection from vehicles. Guard posts or other approved means shall be provided to protect storage tanks and connected piping, valves and fittings; dispensing areas; and use areas subject to vehicular damage in accordance with Section 312.

    5003.9.4 Electrical wiring and equipment. Electrical wiring and equipment shall be installed and maintained in accordance with the California Electrical Code.

    5003.9.5 Static accumulation. Where processes or conditions exist where a flammable mixture could be ignited by static electricity, means shall be provided to prevent the accumulation of a static charge.

    5003.9.6 Protection from light. Materials that are sensitive to light shall be stored in containers designed to protect them from such exposure.

    5003.9.7 Shock padding. Materials that are shock sensitive shall be padded, suspended or otherwise protected against accidental dislodgement and dislodgement during seismic activity.

    2025 CALIFORNIA FIRE CODE 50-17

    on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

    HAZARDOUS MATERIALS—GENERAL PROVISIONS

    5003.9.8 Separation of incompatible materials. Incompatible materials in storage and storage of materials that are incompatible with materials in use shall be separated where the stored materials are in containers having a capacity of more than 5 pounds (2 kg), 0.5 gallon (2 L) or any amount of compressed gases. Separation shall be accomplished by:

    1. Segregating incompatible materials in storage by a distance of not less than 20 feet (6096 mm).

    2. Isolating incompatible materials in storage by a noncombustible partition extending not less than 18 inches (457 mm) above and to the sides of the stored material.

    3. Storing liquid and solid materials in hazardous material storage cabinets.

    4. Storing compressed gases in gas cabinets or exhausted enclosures in accordance with Sections 5003.8.5 and 5003.8.6.

    Materials that are incompatible shall not be stored within the same cabinet or exhausted enclosure.

    5003.9.9 Shelf storage. Shelving shall be of substantial construction, and shall be braced and anchored in accordance with the seismic design requirements of the California Building Code for the seismic design category in which the material is located. Shelving shall be treated, coated or constructed of materials that are compatible with the hazardous materials stored. Shelves shall be provided with a lip or guard where used for the storage of individual containers.

    Shelf storage of hazardous materials shall be maintained in an orderly manner.

    Exceptions:

    1. Storage in hazardous material storage cabinets or laboratory furniture specifically designed for such use.
    2. Storage of hazardous materials in amounts not requiring a permit in accordance with Section 5001.5.

    5003.9.10 Safety cans. Safety cans shall be listed in accordance with UL 30 where used to increase the maximum allowable quantities per control area of flammable or combustible liquids in accordance with Table 5003.1.1(1). Safety cans listed in accordance with UL 1313 are allowed for flammable and combustible liquids where not used to increase the maximum allowable quantities per control area and for other hazardous material liquids in accordance with the listing.

    5003.10 Handling and transportation. In addition to the requirements of Section 5003.2, the handling and transportation of hazardous materials in corridors or enclosures for stairways and ramps shall be in accordance with Sections 5003.10.1 through 5003.10.3.6.

  • CFC § 5003.8.7.2 High relevance — show source text

    Joints shall be riveted or welded and shall be tight fitting. 2. The bottoms of cabinets utilized for the storage of liquids shall be liquid tight to a minimum height of 2 inches (51 mm).

    5003.8.7.2 Doors. Doors shall be well fitted, self-closing and equipped with a self-latching device.

    5003.8.7.3 Electrical. Electrical equipment and devices within cabinets used for the storage of hazardous gases or liquids shall be in accordance with the California Electrical Code.

    5003.8.7.4 Warning markings. Cabinets shall be clearly identified in an approved manner with red letters on a contrasting background to read:

    HAZARDOUS—KEEP FIRE AWAY

    5003.9 General safety precautions. General precautions for the safe storage, handling or care of hazardous materials shall be in accordance with Sections 5003.9.1 through 5003.9.10.

    5003.9.1 Personnel training and written procedures. Persons responsible for the operation of areas in which hazardous materials are stored, dispensed, handled or used shall be familiar with the chemical nature of the materials and the appropriate mitigating actions necessary in the event of fire, leak or spill.

    5003.9.1.1 Fire department liaison. Responsible persons shall be designated and trained to be liaison personnel to the fire department. These persons shall aid the fire department in preplanning emergency responses and identifying the locations where hazardous materials are located, and shall have access to Safety Data Sheets and be knowledgeable in the site’s emergency response procedures.

    5003.9.2 Security. Storage, dispensing, use and handling areas shall be secured against unauthorized entry and safeguarded in a manner approved by the fire code official.

    5003.9.3 Protection from vehicles. Guard posts or other approved means shall be provided to protect storage tanks and connected piping, valves and fittings; dispensing areas; and use areas subject to vehicular damage in accordance with Section 312.

    5003.9.4 Electrical wiring and equipment. Electrical wiring and equipment shall be installed and maintained in accordance with the California Electrical Code.

    5003.9.5 Static accumulation. Where processes or conditions exist where a flammable mixture could be ignited by static electricity, means shall be provided to prevent the accumulation of a static charge.

    5003.9.6 Protection from light. Materials that are sensitive to light shall be stored in containers designed to protect them from such exposure.

    5003.9.7 Shock padding. Materials that are shock sensitive shall be padded, suspended or otherwise protected against accidental dislodgement and dislodgement during seismic activity.

    2025 CALIFORNIA FIRE CODE 50-17

    on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

    HAZARDOUS MATERIALS—GENERAL PROVISIONS

    5003.9.8 Separation of incompatible materials. Incompatible materials in storage and storage of materials that are incompatible with materials in use shall be separated where the stored materials are in containers having a capacity of more than 5 pounds (2 kg), 0.5 gallon (2 L) or any amount of compressed gases. Separation shall be accomplished by:

    1. Segregating incompatible materials in storage by a distance of not less than 20 feet (6096 mm).
    2. Isolating incompatible materials in storage by a noncombustible partition extending not less than 18 inches (457 mm) above and to the sides of the stored material.
  • CFC § 2704.3 High relevance — show source text

    2704.3 Indoor storage outside of fabrication areas. The indoor storage of hazardous materials outside of fabrication areas shall be in accordance with Sections 2704.3.1 through 2704.3.3.

    2704.3.1 HPM storage. The indoor storage of HPM in quantities greater than those listed in Sections 5003.1.1 and 5704.3.4 shall be in a room complying with the requirements of the California Building Code and this code for a liquid storage room, HPM room or gas room as appropriate for the materials stored.

    2704.3.2 Other hazardous materials storage. The indoor storage of other hazardous materials shall comply with Sections 5001, 5003 and 5004 and other applicable provisions of this code.

    2704.3.3 Separation of incompatible hazardous materials. Incompatible hazardous materials in storage shall be separated from each other in accordance with Section 5003.9.8.

    SECTION 2705—USE AND HANDLING

    2705.1 General. The use and handling of hazardous materials shall comply with this section, Section 2703 and other applicable provisions of this code.

    2705.2 Fabrication areas. The use of hazardous materials in fabrication areas shall be in accordance with Sections 2705.2.1 through 2705.2.3.4.

    2705.2.1 Location of HPM in use in fabrication areas. Hazardous production materials in use in fabrication areas shall be within approved or listed gas cabinets, exhausted enclosures or a workstation.

    2025 CALIFORNIA FIRE CODE 27-9

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    SEMICONDUCTOR FABRICATION FACILITIES

    2705.2.2 Maximum aggregate quantities in fabrication areas. The aggregate quantities of hazardous materials in a single fabrication area shall comply with Section 2704.2.2 and Table 2704.2.2.1. The quantity of HPM in use at a workstation shall not exceed the quantities listed in Table 2705.2.2.

    TABLE 2705.2.2—MAXIMUM QUANTITIES OF HPM AT A WORKSTATIONd Col2 Col3
    HPM CLASSIFICATION STATE MAXIMUM QUANTITY
    Flammable, highly toxic, pyrophoric and toxic combined Gas Combined aggregate volume of all cylinders at a workstation shall
    not exceed an internal cylinder volume of 39.6 gallons or 5.29
    cubic feet
    Flammable Liquid 15 gallonsa, b
    Flammable Solid 5 poundsa, b
    Corrosive Gas Combined aggregate volume of all cylinders at a workstation shall
    not exceed an internal cylinder volume of 39.6 gallons or 5.29
    cubic feet
    Corrosive Liquid Use-open system: 25 gallonsb
    Use-closed system: 150 gallonsb, e
    Corrosive Solid 20 poundsa, b
    Highly toxic Liquid 15 gallonsa, b
    Highly toxic Solid 5 poundsa, b
    Oxidizer Gas Combined aggregate volume of all cylinders at a workstation shall
    not exceed an internal cylinder volume of 39.6 gallons or 5.29
    cubic feet
    Oxidizer Liquid Use-open system: 12 gallonsb Use-closed system: 60 gallonsb
    Oxidizer Solid 20 poundsa,
  • CFC § 5004.11 High relevance — show source text

    5004.11 Clearance from combustibles. The area surrounding an outdoor storage area or tank shall be kept clear of combustible materials and vegetation for a minimum distance of 25 feet (7620 mm).

    5004.12 Noncombustible floor. Except for surfacing, floors of storage areas shall be of noncombustible construction.

    5004.13 Weather protection. Where overhead noncombustible construction is provided for sheltering outdoor hazardous material storage areas, such storage shall not be considered indoor storage where the area is constructed in accordance with the requirements for weather protection as required by the California Building Code .

    Exception: Storage of explosive materials shall be considered as indoor storage.

    5004.14 Outdoor storage location. Outdoor storage areas for hazardous materials shall be located as required by Section 5003.12 except where material-specific requirements, including requirements in referenced standards, are provided in other chapters of this code.

    SECTION 5005—USE, DISPENSING AND HANDLING

    5005.1 General. Use, dispensing and handling of hazardous materials in amounts exceeding the maximum allowable quantity per control area set forth in Section 5003.1 shall be in accordance with Sections 5001, 5003 and 5005. Use, dispensing and handling of hazardous materials in amounts not exceeding the maximum allowable quantity per control area set forth in Section 5003.1 shall be in accordance with Sections 5001 and 5003.

    5005.1.1 Separation of incompatible materials. Separation of incompatible materials shall be in accordance with Section 5003.9.8.

    5005.1.2 Noncombustible floor. Except for surfacing, floors of areas where liquid or solid hazardous materials are dispensed or used in open systems shall be of noncombustible, liquid-tight construction.

    5005.1.3 Spill control and secondary containment for hazardous material liquids. Where required by other provisions of Section 5005, spill control and secondary containment shall be provided for hazardous material liquids in accordance with Section 5004.2.

    5005.1.4 Limit controls. Limit controls shall be provided in accordance with Sections 5005.1.4.1 through 5005.1.4.4.

    5005.1.4.1 High-liquid-level control. Open tanks in which liquid hazardous materials are used shall be equipped with a liquid-level limit control or other means to prevent overfilling of the tank.

    5005.1.4.2 Low-liquid-level control. Approved safeguards shall be provided to prevent a low-liquid level in a tank from creating a hazardous condition, including but not limited to, overheating of a tank or its contents.

    5005.1.4.3 Temperature control. Temperature control shall be provided in accordance with Section 5004.8.1.

    5005.1.4.4 Pressure control. Pressure control shall be provided in accordance with Section 5004.8.2.

    5005.1.5 Standby or emergency power. Where mechanical ventilation, treatment systems, temperature control, manual alarm, detection or other electrically operated systems are required by this code, such systems shall be provided with emergency or standby power in accordance with Section 1203.

    5005.1.5.1 Exempt applications. Standby power for mechanical ventilation, treatment systems and temperature control systems shall not be required where an approved fail-safe engineered system is installed.

  • CFC § 5004.7.2 High relevance — show source text

    5004.7.2 Fail-safe engineered systems. Standby power for mechanical ventilation, treatment systems and temperature control systems shall not be required where an approved fail-safe engineered system is installed.

    5004.8 Limit controls. Limit controls shall be provided in accordance with Sections 5004.8.1 and 5004.8.2.

    5004.8.1 Temperature control. Materials that must be kept at temperatures other than normal ambient temperatures to prevent a hazardous reaction shall be provided with an approved means to maintain the temperature within a safe range. Redundant temperature control equipment that will operate on failure of the primary temperature control system shall be provided. Where approved, alternative means that prevent a hazardous reaction are allowed.

    5004.8.2 Pressure control. Stationary tanks and equipment containing hazardous material liquids that can generate pressures exceeding design limits because of exposure fires or internal reaction shall have some form of construction or other approved means that will relieve excessive internal pressure. The means of pressure relief shall vent to an approved location or to an exhaust scrubber or treatment system where required by Chapter 60.

    50-24 2025 CALIFORNIA FIRE CODE

    on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

    HAZARDOUS MATERIALS—GENERAL PROVISIONS

    5004.9 Emergency alarm. An approved manual emergency alarm system shall be provided in buildings, rooms or areas used for storage of hazardous materials. Emergency alarm-initiating devices shall be installed outside of each interior exit or exit access door of storage buildings, rooms or areas. Activation of an emergency alarm-initiating device shall sound a local alarm to alert occupants of an emergency situation involving hazardous materials.

    5004.10 Supervision and monitoring. Emergency alarm, detection and automatic fire-extinguishing systems required by Section 5004 shall be electrically supervised and monitored by an approved supervising station or, where approved, shall initiate an audible and visual signal at a constantly attended on-site location.

    5004.11 Clearance from combustibles. The area surrounding an outdoor storage area or tank shall be kept clear of combustible materials and vegetation for a minimum distance of 25 feet (7620 mm).

    5004.12 Noncombustible floor. Except for surfacing, floors of storage areas shall be of noncombustible construction.

    5004.13 Weather protection. Where overhead noncombustible construction is provided for sheltering outdoor hazardous material storage areas, such storage shall not be considered indoor storage where the area is constructed in accordance with the requirements for weather protection as required by the California Building Code .

    Exception: Storage of explosive materials shall be considered as indoor storage.

    5004.14 Outdoor storage location. Outdoor storage areas for hazardous materials shall be located as required by Section 5003.12 except where material-specific requirements, including requirements in referenced standards, are provided in other chapters of this code.

    SECTION 5005—USE, DISPENSING AND HANDLING

    5005.1 General. Use, dispensing and handling of hazardous materials in amounts exceeding the maximum allowable quantity per control area set forth in Section 5003.1 shall be in accordance with Sections 5001, 5003 and 5005. Use, dispensing and handling of hazardous materials in amounts not exceeding the maximum allowable quantity per control area set forth in Section 5003.1 shall be in accordance with Sections 5001 and 5003.

    5005.1.1 Separation of incompatible materials. Separation of incompatible materials shall be in accordance with Section 5003.9.8.

  • CFC § 5904.2 High relevance — show source text

    5904.2 Outdoor storage. Outdoor storage of flammable solids in amounts exceeding the maximum allowable quantities per control area indicated in Table 5003.1.1(1) shall be in accordance with Sections 5001, 5003, 5004 and this chapter. Outdoor storage of magnesium shall be in accordance with Section 5906.

    5904.2.1 Distance from storage to exposures. Outdoor storage of flammable solids shall not be located within 20 feet (6096 mm) of a building, lot line, public street, public alley, public way or means of egress. A 2-hour fire barrier without openings or penetrations and extending 30 inches (762 mm) above and to the sides of the storage area is allowed in lieu of such distance. The wall shall either be an independent structure, or the exterior wall of the building adjacent to the storage area.

    5904.2.2 Pile size limits. Outdoor storage of flammable solids shall be separated into piles not larger than 5,000 cubic feet (141 m [3] ) each. Piles shall be separated by aisles with a minimum width of not less than one-half the pile height or 10 feet (3048 mm), whichever is greater.

    SECTION 5905—USE

    5905.1 General. The use of flammable solids in amounts exceeding the maximum allowable quantity per control area indicated in Table 5003.1.1(1) or Table 5003.1.1(3) shall be in accordance with Sections 5001, 5003, 5005 and this chapter. The use of magnesium shall be in accordance with Section 5906.

    SECTION 5906—MAGNESIUM

    5906.1 General. Storage, use, handling and processing of magnesium, including the pure metal and alloys of which the major part is magnesium, shall be in accordance with Chapter 50 and Sections 5906.2 through 5906.5.8.

    5906.2 Storage of magnesium articles. The storage of magnesium shall comply with Sections 5906.2.1 through 5906.4.3.

    2025 CALIFORNIA FIRE CODE 59-3

    on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

    FLAMMABLE SOLIDS

    5906.2.1 Storage of greater than 50 cubic feet. Magnesium storage in quantities greater than 50 cubic feet (1.4 m [3] ) shall be separated from storage of other materials that are either combustible or in combustible containers by aisles. Piles shall be separated by aisles with a minimum width of not less than the pile height. 5906.2.2 Storage of greater than 1,000 cubic feet. Magnesium storage in quantities greater than 1,000 cubic feet (28 m [3] ) shall be separated into piles not larger than 1,000 cubic feet (28 m [3] ) each. Piles shall be separated by aisles with a minimum width of not less than the pile height. Such storage shall not be located in nonsprinklered buildings of Type III, IV or V construction, as defined in the California Building Code .

  • CFC § 6703.1 High relevance — show source text

    WATER-REACTIVE MATERIAL.

    Class 3.

    Class 2.

    Class 1.

    SECTION 6703—GENERAL REQUIREMENTS

    6703.1 Quantities not exceeding the maximum allowable quantity per control area. The storage and use of water-reactive solids and liquids in amounts not exceeding the maximum allowable quantity per control area indicated in Section 5003.1 shall be in accordance with Sections 5001, 5003, 6701 and 6703.

    6703.2 Quantities exceeding the maximum allowable quantity per control area. The storage and use of water-reactive solids and liquids in amounts exceeding the maximum allowable quantity per control area indicated in Section 5003.1 shall be in accordance with Chapter 50 and this chapter.

    SECTION 6704—STORAGE

    6704.1 Indoor storage. Indoor storage of water-reactive solids and liquids in amounts exceeding the maximum allowable quantity per control area indicated in Table 5003.1.1(1), shall be in accordance with Sections 5001, 5003, 5004 and this chapter.

    6704.1.1 Detached storage. Storage of water-reactive solids and liquids shall be in detached buildings where required by Section 5003.8.2.

    6704.1.2 Liquid-tight floor. In addition to the provisions of Section 5004.12, floors in storage areas for water-reactive solids and liquids shall be of liquid-tight construction.

    6704.1.3 Waterproof room. Rooms or areas used for the storage of water-reactive solids and liquids shall be constructed in a manner that resists the penetration of water through the use of waterproof materials. Piping carrying water for other than approved automatic sprinkler systems shall not be within such rooms or areas.

    6704.1.4 Watertight containers. Where Class 3 water-reactive solids and liquids are stored in areas equipped with an automatic sprinkler system, the materials shall be stored in closed watertight containers. 6704.1.5 Storage configuration. Water-reactive solids and liquids stored in quantities greater than 500 cubic feet (14 m [3] ) shall be separated into piles, each not larger than 500 cubic feet (14 m [3] ). Aisle widths between piles shall be not less than the height of the pile or 4 feet (1219 mm), whichever is greater.

    Exception: Water-reactive solids and liquids stored in tanks.

    Class 2 water-reactive solids and liquids shall not be stored in basements unless such materials are stored in closed watertight containers or tanks.

    Class 3 water-reactive solids and liquids shall not be stored in basements.

    Class 2 or 3 water-reactive solids and liquids shall not be stored with flammable liquids.

    2025 CALIFORNIA FIRE CODE 67-3

    on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

    WATER-REACTIVE SOLIDS AND LIQUIDS

    6704.1.6 Explosion control. Indoor storage rooms, areas and buildings containing Class 2 or 3 water-reactive solids and liquids shall be provided with explosion control in accordance with Section 911.

    6704.2 Outdoor storage. Outdoor storage of water-reactive solids and liquids in quantities exceeding the maximum allowable quantity per control area indicated in Table 5003.1.1(3) shall be in accordance with Sections 5001, 5003, 5004 and this chapter.

  • CFC § 5902.1 High relevance — show source text

    SECTION 5902—DEFINITIONS

    5902.1 Definitions. The following terms are defined in Chapter 2:

    FLAMMABLE SOLID.

    MAGNESIUM.

    SECTION 5903—GENERAL REQUIREMENTS

    5903.1 Quantities not exceeding the maximum allowable quantity per control area. The storage and use of flammable solids in amounts not exceeding the maximum allowable quantity per control area as indicated in Section 5003.1 shall be in accordance with Sections 5001, 5003 and 5901.

    5903.2 Quantities exceeding the maximum allowable quantity per control area. The storage and use of flammable solids exceeding the maximum allowable quantity per control area as indicated in Section 5003.1 shall be in accordance with Chapter 50 and this chapter.

    SECTION 5904—STORAGE

    5904.1 Indoor storage. Indoor storage of flammable solids in amounts exceeding the maximum allowable quantity per control area indicated in Table 5003.1.1(1) shall be in accordance with Sections 5001, 5003, 5004 and this chapter. 5904.1.1 Pile size limits and location. Flammable solids stored in quantities greater than 1,000 cubic feet (28 m [3] ) shall be separated into piles each not larger than 1,000 cubic feet (28 m [3] ).

    5904.1.2 Aisles. Aisle widths between piles shall be not less than the height of the piles or 4 feet (1219 mm), whichever is greater.

    5904.1.3 Basement storage. Flammable solids shall not be stored in basements .

    5904.2 Outdoor storage. Outdoor storage of flammable solids in amounts exceeding the maximum allowable quantities per control area indicated in Table 5003.1.1(1) shall be in accordance with Sections 5001, 5003, 5004 and this chapter. Outdoor storage of magnesium shall be in accordance with Section 5906.

    5904.2.1 Distance from storage to exposures. Outdoor storage of flammable solids shall not be located within 20 feet (6096 mm) of a building, lot line, public street, public alley, public way or means of egress. A 2-hour fire barrier without openings or penetrations and extending 30 inches (762 mm) above and to the sides of the storage area is allowed in lieu of such distance. The wall shall either be an independent structure, or the exterior wall of the building adjacent to the storage area.

    5904.2.2 Pile size limits. Outdoor storage of flammable solids shall be separated into piles not larger than 5,000 cubic feet (141 m [3] ) each. Piles shall be separated by aisles with a minimum width of not less than one-half the pile height or 10 feet (3048 mm), whichever is greater.

    SECTION 5905—USE

    5905.1 General. The use of flammable solids in amounts exceeding the maximum allowable quantity per control area indicated in Table 5003.1.1(1) or Table 5003.1.1(3) shall be in accordance with Sections 5001, 5003, 5005 and this chapter. The use of magnesium shall be in accordance with Section 5906.

    SECTION 5906—MAGNESIUM

  • CFC § 1.3 High relevance — show source text

    foodstuffs or consumer products, and cosmetics containing
    not more than 50 percent by volume of water-miscible liquids, with the remainder of
    the solutions not being flammable, is not limited.
    To qualify for this allowance, such materials shall be packaged in individual containers
    not exceeding 1.3 gallons.| |Any|Agricultural materials|The quantity of agricultural materials stored or utilized for agricultural purposes on the
    premises is not limited.| |Any|Energy storage|The quantity of hazardous materials in stationary storage battery systems is not
    limited.| |Any|Energy storage|The quantity of hazardous materials in stationary fuel cell power systems is not limited.| |Any|Energy storage|The quantity of hazardous materials in capacitor energy storage systems is not limited.| |Any|Refrigeration systems|The quantity of refrigerants in refrigeration systems is not limited.| |For SI: 1 gallon = 3.785 L, °C = (°F – 32)/1.8.
    a. Exempted materials and conditions listed in this table are required to comply with provisions of this code that are not based on exceeding maximum allowable quantities in
    Section 5003.|For SI: 1 gallon = 3.785 L, °C = (°F – 32)/1.8.
    a. Exempted materials and conditions listed in this table are required to comply with provisions of this code that are not based on exceeding maximum allowable quantities in
    Section 5003.|For SI: 1 gallon = 3.785 L, °C = (°F – 32)/1.8.
    a. Exempted materials and conditions listed in this table are required to comply with provisions of this code that are not based on exceeding maximum allowable quantities in
    Section 5003.|

    5003.1.2 Conversion. Where quantities are indicated in pounds and where the weight per gallon of the liquid is not provided to the fire code official, a conversion factor of 10 pounds per gallon (1.2 kg/L) shall be used.

    5003.1.3 Quantities not exceeding the maximum allowable quantity per control area. The storage, use and handling of hazardous materials in quantities not exceeding the maximum allowable quantity per control area indicated in Tables 5003.1.1(1) through 5003.1.1(4) shall be in accordance with Sections 5001 and 5003.

    5003.1.4 Quantities exceeding the maximum allowable quantity per control area. The storage and use of hazardous materials in quantities exceeding the maximum allowable quantity per control area indicated in Tables 5003.1.1(1) through 5003.1.1(4) shall be in accordance with this chapter.

    5003.2 Systems, equipment and processes. Systems, equipment and processes utilized for storage, dispensing, use or handling of hazardous materials shall be in accordance with Sections 5003.2.1 through 5003.2.9.

    5003.2.1 Design and construction of containers, cylinders and tanks. Containers, cylinders and tanks shall be designed and constructed in accordance with approved standards. Containers, cylinders, tanks and other means used for containment of hazardous materials shall be of an approved type. Pressure vessels not meeting DOTn requirements for transportation shall comply with the ASME Boiler and Pressure Vessel Code.

  • CFC § 1.11. High relevance — show source text
    • The California Code of Regulations (CCR), Title 19, Division 1 provisions that are found in the California Fire Code are a reprint from the current CCR, Title 19, Division 1 text for the code user’s convenience only. The scope, applicability and appeals procedures of CCR, Title 19, Division I remain the same. The state agency does not adopt sections identified by the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.

    2025 CALIFORNIA FIRE CODE 59-1

    on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

    59-2 2025 CALIFORNIA FIRE CODE

    on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

    59 FLAMMABLE SOLIDS

    User notes:

    About this chapter: Chapter 59 addresses general requirements for storage and handling of flammable solids, especially magnesium; however, it is important to note that several other solid materials, including such metals as titanium, zirconium, hafnium, calcium, zinc, sodium, lithium, potassium, sodium/potassium alloys, uranium, thorium and plutonium, can be explosion hazards under the right conditions. Some of these metals are almost exclusively laboratory materials but because of where they are used, fire service personnel must be trained to handle emergency situations. Because uranium, thorium and plutonium are also radioactive materials, they pose more specialized problems for fire service personnel.

    SECTION 5901—GENERAL

    5901.1 Scope. The storage and use of flammable solids shall be in accordance with this chapter.

    5901.2 Permits. Permits shall be required as set forth in Section 105.5.

    SECTION 5902—DEFINITIONS

    5902.1 Definitions. The following terms are defined in Chapter 2:

    FLAMMABLE SOLID.

    MAGNESIUM.

    SECTION 5903—GENERAL REQUIREMENTS

    5903.1 Quantities not exceeding the maximum allowable quantity per control area. The storage and use of flammable solids in amounts not exceeding the maximum allowable quantity per control area as indicated in Section 5003.1 shall be in accordance with Sections 5001, 5003 and 5901.

    5903.2 Quantities exceeding the maximum allowable quantity per control area. The storage and use of flammable solids exceeding the maximum allowable quantity per control area as indicated in Section 5003.1 shall be in accordance with Chapter 50 and this chapter.

    SECTION 5904—STORAGE

    5904.1 Indoor storage. Indoor storage of flammable solids in amounts exceeding the maximum allowable quantity per control area indicated in Table 5003.1.1(1) shall be in accordance with Sections 5001, 5003, 5004 and this chapter. 5904.1.1 Pile size limits and location. Flammable solids stored in quantities greater than 1,000 cubic feet (28 m [3] ) shall be separated into piles each not larger than 1,000 cubic feet (28 m [3] ).

    5904.1.2 Aisles. Aisle widths between piles shall be not less than the height of the piles or 4 feet (1219 mm), whichever is greater.

    5904.1.3 Basement storage. Flammable solids shall not be stored in basements .

  • CFC § 4-43 High relevance — show source text

    2025 CALIFORNIA BUILDING CODE 4-43

    on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

    SPECIAL DETAILED REQUIREMENTS BASED ON OCCUPANCY AND USE

    [F] 415.8.1 Multiple hazards. Group H-2 or H-3 occupancies containing materials that are in themselves both physical and health hazards in quantities exceeding the maximum allowable quantities per control area in Table 307.1(2) shall comply with requirements for Group H-2, H-3 or H-4 occupancies as applicable.

    [F] 415.8.2 Separation of incompatible materials. Hazardous materials other than those specified in Table 415.6.5 shall be allowed in manufacturing, processing, dispensing, use or storage areas when separated from incompatible materials in accordance with the provisions of the California Fire Code .

    [F] 415.8.3 Water reactives. Group H-2 and H-3 occupancies containing water-reactive materials shall be resistant to water penetration. Piping for conveying liquids shall not be over or through areas containing water reactives, unless isolated by approved liquid-tight construction.

    Exception: Fire protection piping shall be permitted over or through areas containing water reactives without isolating it with liquid-tight construction.

    [F] 415.8.4 Floors in storage rooms. Floors in storage areas for organic peroxides, oxidizers, pyrophoric materials, unstable (reactive) materials and water-reactive solids and liquids shall be of liquid-tight, noncombustible construction.

    [F] 415.8.5 Waterproof room. Rooms or areas used for the storage of water-reactive solids and liquids shall be constructed in a manner that resists the penetration of water through the use of waterproof materials. Piping carrying water for other than approved automatic sprinkler systems shall not be within such rooms or areas.

    [F] 415.9 Group H-2. Occupancies in Group H-2 shall be constructed in accordance with Sections 415.9.1 through 415.9.3 and the California Fire Code.

    [F] 415.9.1 Flammable and combustible liquids. The storage, handling, processing and transporting of flammable and combustible liquids in Group H-2 and H-3 occupancies shall be in accordance with Sections 415.9.1.1 through 415.9.1.9, the California Mechanical Code and the California Fire Code .

    [F] 415.9.1.1 Mixed occupancies. Where the storage tank area is located in a building of two or more occupancies and the quantity of liquid exceeds the maximum allowable quantity for one control area, the use shall be completely separated from adjacent occupancies in accordance with the requirements of Section 508.4.

    [F] 415.9.1.1.1 Height exception. Where storage tanks are located within a building not more than one story above grade plane, the height limitation of Section 504 shall not apply for Group H.

    [F] 415.9.1.2 Tank protection. Storage tanks shall be noncombustible and protected from physical damage. Fire barriers or horizontal assemblies or both around the storage tanks shall be permitted as the method of protection from physical damage.

    [F] 415.9.1.3 Tanks. Storage tanks shall be approved tanks conforming to the requirements of the California Fire Code .

  • CFC § 6404.1.3 Medium relevance — show source text

    6404.1.3 Pyrophoric gases. Storage of pyrophoric gases shall be in detached buildings where required by Section 5003.8.2.

    6404.1.4 Separation from incompatible materials. In addition to the requirements of Section 5003.9.8, indoor storage of pyrophoric materials shall be isolated from incompatible hazardous materials by 1-hour fire barriers with openings protected in accordance with the California Building Code.

    Exception: Storage in approved hazardous materials storage cabinets constructed in accordance with Section 5003.8.7.

    6404.2 Outdoor storage. Outdoor storage of pyrophoric materials in amounts exceeding the maximum allowable quantity per control area indicated in Table 5003.1.1(3) shall be in accordance with Sections 5001, 5003 and 5004, and this chapter.

    The storage of silane gas, and gas mixtures with a silane concentration of 1.37 percent or more by volume, shall be in accordance with ANSI/CGA G-13.

    2025 CALIFORNIA FIRE CODE 64-3

    on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

    PYROPHORIC MATERIALS

    6404.2.1 Distance from storage to exposures. The separation of pyrophoric solids, liquids and gases from buildings, lot lines, public streets, public alleys, public ways or means of egress shall be in accordance with the following:

    1. Solids and liquids. Two times the separation required by Chapter 57 for Class IB flammable liquids.
    2. Gases. The location and maximum amount of pyrophoric gas per storage area shall be in accordance with Table 6404.2.1.
    TABLE 6404.2.1—PYROPHORIC GASES—DISTANCE FROM STORAGE TO EXPOSURESa Col2 Col3 Col4 Col5 Col6 Col7
    MAXIMUM
    AMOUNT PER
    STORAGE AREA
    (cubic feet)    		 MINIMUM
    DISTANCE
    BETWEEN
    STORAGE AREAS
    (feet)    		 MINIMUM
    DISTANCE TO
    LOT LINES OF
    PROPERTY THAT
    CAN BE BUILT ON
    (feet)    		 MINIMUM
    DISTANCE TO
    PUBLIC
    **STREETS,

Frequently asked questions

When do I have to separate incompatible materials — is there a weight/volume threshold?

The separation rule applies when containers are more than 5 pounds (2 kg) or more than 0.5 gallon (2 L), or for any amount of compressed gases. See § 5003.9.8 .

Can I store incompatibles in the same cabinet if they’re in small containers?

No — the code explicitly states incompatible materials shall not be stored within the same cabinet or exhausted enclosure. Cabinets are allowed as a method of separation only when the materials stored in that cabinet are compatible. See § 5003.9.8 and § 5003.8.7 .

Is a short partition (18 inches above) really sufficient?

The code allows a noncombustible partition extending not less than 18 inches (457 mm) above and to the sides as an isolation option in § 5003.9.8. For certain highly hazardous materials the code requires more protective construction (for example, 1‑hour fire barriers for pyrophoric materials in § 6404.1.4). See § 5003.9.8 and § 6404.1.4 .

What about compressed gases — any special rules?

Yes. Compressed gases must be stored in gas cabinets or exhausted enclosures per § 5003.9.8, and gas cabinets must have exhaust ventilation at negative pressure and are limited in cylinder count (e.g., maximum 3 cylinders per gas cabinet) per § 5003.8.6. See § 5003.9.8 and § 5003.8.6 .

Who decides if two materials are “incompatible”?

The code uses the term incompatible materials (definition is in Chapter 2 of the code). If it’s unclear, consult Safety Data Sheets and coordinate with your fire code official; a technical opinion or engineered analysis may be required for unusual materials (authority provisions are in the California Building Code and code enforcement sections). The retrieval here did not include the full chapter-2 definition text.

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