NFPA 55 Standard for Gases Questions 1

[Jeremiah187]

Folks,

I'm hoping someone will know this.

NFPA 55 10.3.2.2.3 States:
Portions of wall less than 10 ft (measured horizontally) from any part of a system shall have a fire resistance rating of at least 1/2 hour.

NFPA 55 10.3.2.2.5. States:
Portions of wall less than 10 ft (measured horizontally) from any part of a system shall have a fire resistance rating of at least 1 hour.

Same exact phrase with different fire ratings...

Im thinking one should say measaured vertically?

Does anyone know anything about this?

Cheers,
Jeremiah

 

[stookeyfpe]

Jeremiah

Typically when one builds a wall as a fire-resistive assembly, the entire wall is built of the same material. This is especially true for exterior walls because the fire-resistance rating will be dictated by the adopted building code based on its proximity to the property line or the building's occupancy classification. In other cases the material of construction may be inherently fire-resistive, e.g., concrete masonry unit walls or precast concrete walls.