Fire Protection Solutions for Ordinary Hazard Areas within Light Hazard Buildings

BlazeMaster® Chlorinated Polyvinyl Chloride (CPVC) has established itself as a reliable and effective pipe material for fire protection systems over the last 40 years, particularly within Light Hazard residential and commercial occupancies as defined by the National Fire Protection Association (NFPA).

While BlazeMaster CPVC is not listed or approved for use in Ordinary Hazard (OH) occupancies, there is an exemption in the NFPA 13 Standard that permits its use in OH areas not exceeding 400 ft² (37 m²) located within occupancies otherwise classified as Light Hazard. Additionally, the NFPA 13R Standard permits its use in OH areas not exceeding 800 ft² (74 m²) for the same and allows for in rooms over 800 ft² (74 m²) concealed behind 3/8 in (10 mm) gypsum wallboard or ½ in (13 mm) plywood.

Understanding NFPA 13 Classifications

NFPA 13 categorizes occupancies based on the level of fire hazard they present. These categories include:

• Light Hazard. This category anticipates that the quantity or combustibility of contents will be low and that fires will have relatively low rates of heat release.
• Ordinary Hazard Group 1. This category anticipates the combustibility of contents is low, stockpiles of combustibles do not exceed 8 ft. (2.4 m), and the rate of heat release for a fire is greater than that for the light-hazard classification.
• Ordinary Hazard Group 2. This category anticipates occupancies with combustibility of contents, storage heights, and obstruction features as moderate to high, where stockpiles do not exceed 12 ft (3.7 m), and the rate of heat release is greater than for OH Group 1.

NFPA 13R OH Area Exemption

The 2025 Ed. of NFPA 13R, Standard for the Installation of Sprinkler Systems in Low-Rise Residential Occupancies, states the following:

1. In rooms 800 ft² (74 m²) or less, piping shall be permitted to be installed either exposed in accordance with its listing or concealed behind a minimum of one layer of 3⁄8 in. (10 mm) thick gypsum wallboard or 1⁄2 in. (13 mm) thick plywood.
2. In rooms over 800 ft² (74 m²), piping shall be permitted to be installed concealed behind a minimum of one layer of 3⁄8 in. (10 mm) thick gypsum wallboard or 1⁄2 in. (13 mm) thick plywood.

Practical Applications of the NFPA 13R 800 ft2 OH Exemption

The exemption allowing BlazeMaster CPVC to be used in OH areas not exceeding 800 ft² within Light Hazard environments can be particularly useful in the following scenarios:

• Mechanical Rooms: small mechanical rooms within an condominium or apartment building, which might present a higher hazard due to the presence of equipment and electrical systems.
• Storage Areas: limited storage rooms within a Light Hazard occupancy that store materials with moderate combustibility.
• Utility Closets: utility closets that house equipment or supplies that could present a higher fire risk.
• Parking garages: For a parking garage within a NFPA 13R protected structure that is over 800 ft², it is acceptable to use BlazeMaster CPVC behind 3/8 in. (10 mm) gypsum wallboard.

NFPA 13 OH Area Exemption

The 2022 Ed. Of NFPA 13, Standard for the Installation of Sprinkler Systems, states the following:

16.3.9.6 Nonmetallic pipe listed for light hazard occupancies shall be permitted to be installed in ordinary hazard rooms of otherwise light hazard occupancies where the room does not exceed 400 ft² (37 m²).

16.3.9.6.1 Nonmetallic pipe installed in accordance with 16.3.9.6 shall be permitted to be installed exposed, in accordance with the listing.

16.3.9.6.2 Where nonmetallic pipe installed in accordance with 16.3.9.6 supplies sprinklers in a private garage within a dwelling unit, and the garage does not exceed 1000 ft² (93 m²) in area, the nonmetallic piping shall be permitted to be protected from the garage compartment by not less than the same wall or ceiling sheathing that is required by the applicable building code.

Practical Applications of the NFPA 13 400 ft² OH Exemption

The exemption allowing BlazeMaster CPVC to be used in OH areas not exceeding 400 ft² within Light Hazard environments can be particularly useful in the following scenarios:

• Mechanical Rooms: small mechanical rooms within an office building, which might present a higher hazard due to the presence of equipment and electrical systems.
• Storage Areas: limited storage rooms within a Light Hazard occupancy that store materials with moderate combustibility.
• Utility Closets: utility closets that house equipment or supplies that could present a higher fire risk.
• Parking garages: for parking garages within a NFPA 13 protected structure that is not over 1000 ft², provided it is protected from the garage compartment by not less than the same wall or ceiling sheathing that is required by the applicable building code.

BlazeMaster CPVC for OH Areas

So, what makes BlazeMaster CPVC suitable for use within limited OH areas?

Several material properties, including high thermal stability, are critical for maintaining the integrity of BlazeMaster CPVC.

Additionally, the smooth internal surface of BlazeMaster fire protection systems reduces friction loss, ensuring efficient water flow and effective sprinkler operation. Unlike metal piping, BlazeMaster CPVC is not susceptible to corrosion, ensuring long-term reliability even in areas that might experience higher levels of wear and tear from corrosion.

Approvals and Standards Compliance

BlazeMaster CPVC is listed for use in Light Hazard occupancies and complies with various standards, including:

• UL 1821 – Thermoplastic Sprinkler Pipe and Fittings for Fire Protection Service
• UL 1887 – Safety Fire Test of Plastic Sprinkler Pipe for Visible Flame and Smoke Characteristics
• ULC / ORD – C199 – Combustible Piping for Sprinkler Systems
• FM 1635 – Plastic Pipe and Fittings for Automatic Sprinkler Systems.

Conclusion

While BlazeMaster CPVC is not approved for use in OH occupancies, the specific exemptions found in NFPA 13 and NFPA 13R for OH areas located within Light Hazard environments offers a valuable solution. By leveraging its superior material properties, compliance with rigorous standards and testing, and proven performance, BlazeMaster CPVC provides a reliable and cost-effective option for maintaining fire protection.