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Venting of duct enclosures.

Discussion in 'Mechanical Codes' started by John shane, Feb 13, 2020.

  1. John shane

    John shane Registered User

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    510.7 Interior Installations In buildings more than one story in height, and in one-story buildings where the roof-ceiling assembly is required to have a fire resistance rating, the ducts shall be enclosed in a continuous enclosure extending from the lowest fire-rated ceiling or floor above the hood, through concealed spaces, to or through the roof, to maintain the integrity of the fire separations required by the applicable building code provisions. The enclosure shall be sealed around the duct at the point of penetration of the first fire-rated barrier after the hood, to maintain the fire resistance rating of the enclosure. The enclosure shall be vented to the exterior of the building through weather-protected openings. [NFPA 96:7.7.1.2 - 7.7.1.4]

    So I have a shaft as an enclosure, what are the methods of venting this with weather protected openings.
     
  2. rgrace

    rgrace Sawhorse

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    Welcome to the forum John. I always find something interesting when reviewing different codes. I am not sure what this means :) The code I work with is the International Mechanical Code (IMC). Your post comes from the Uniform Mechanical Code or California Mechanical code (assuming one in the same for the most part). The equivilant code requirement in the IMC is 506.3.11, and the last sentance of UMC is not included there. Basically the IMC says that the duct enclosure shall be installed from the point of penetration of any ceiling, wall or floor to the outlet terminal. The outlet terminal is generally where the exhaust fan is located (most times). There is nothing about it being "vented" unless it's required when an inline fan or inline pollution control unit is installed (which would actually be "ventilated"). Maybe the term "vented" is a loose term and the key is to be certain that the opening in the exterior of the building for the exhuast system is weather-protected?
     
  3. Builder Bob

    Builder Bob Sawhorse

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    think elevator shaft or mechanical chases - the vent can be a louver that is weather resistant to prevent rain water from coming in.

    Weather Louver
     

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