You need to look at the requirements for existing structures in the IBC which states "The legal occupancy of any structure existing on the date of adoption of this code shall be permitted to continue without change, except as is specifically covered in this code, the International Property Maintenance Code or the International Fire Code, or as is deemed necessary by the building official for the general safety and welfare of the occupants and the public." The requirements for existing structures under the IFC are "No change shall be made in the use or occupancy of any structure that would place the structure in a different division of the same group or occupancy or in a different group of occupancies, unless such structure is made to comply with the requirements of this code and the International Building Code. Subject to the approval of the fire code official, the use or occupancy of an existing structure shall be allowed to be changed and the structure is allowed to be occupied for purposes in other groups without conforming to all the requirements of this code and the International Building Code for those groups, provided the new or proposed use is less hazardous, based on life and fire risk, than the existing use." At the start of the project the Owner of their design professionals should have had a meeting with the appropriate code official to determine the basis of design. Such as will we need to install smoke and heat vents; or is this a change in hazard or occupancy? It is hard to start making changes after construction starts and the change orders come rolling in. Or if "design build" the job goes from "profitable" to "contributions to Owner and/or the lawyers".
In my opinion this should have been determined before the start of the retrofit construction modifications so the contractor is not stuck in the middle. Now just to throw gas into the fire. The IBC Commentary suggests that the increase in travel distances associated with the provision of smoke and heat vents is "because of the increased visibility provided in a fire event if the roof-venting system is properly designed and installed in accordance with Section 910.0." In "Venting" theory, natural convection roof vents rely entirely on the fact that a pressure difference exists across them, tending to push fluid from high pressure to low pressure regions. When a fire occurs in a room, the hot gases rise vertically (buoyancy induced flows) in the form of a plume from the combustion zone and then flow horizontally below the roof until blocked by a vertical barrier (end wall or draft curtain) forming a hot gas layer below the roof. The volume and temperature of gases to be vented are a function of the rate of heat release of the fire and the amount of air entrained into the fire plume. The replacement cold air flows into the room through leakage paths in the outer walls The IBC specifies the requirements for smoke and heat vents when used to permit an increase in travel distances to 400 feet. Essentially, roof vents spaced from 75 feet to 120 feet on center are installed along the roof. Draft curtains from 4 to 6 feet deep segmenting the building into areas ranging from 2,000 to 50,000 square feet are also provided, except where ESFR sprinkler are used to protect the building. The vents are required to be automatic activated by heat responsive devices rated at 100o F to 220o F above ambient. These requirements parallel those contained within NFPA 204 Standard for Smoke and Heat Venting. NFPA 204 is the foundation document upon which the concept of smoke and heat venting in large industrial buildings is based. As noted the requirements specified in IBC parallel these guidelines. Unlike IBC however, NFPA 204 differentiates between sprinklered and non-sprinklered occupancies, providing detailed guidance on the use and application of smoke and heat vents for non-sprinklered occupancies while stating that for sprinklered occupancies See Annex F.3: "Chapters 4 through 10 represent the state of technology of vent and draft curtain board design in the absence of sprinklers. A broadly accepted equivalent design basis for using sprinklers, vents, and curtain boards together for hazard control (e.g., property protection, life safety, water usage, and obscuration) is currently not available. Designers are strongly cautioned that use of venting with automatic sprinklers is an area of ongoing research to determine its benefit and effect in conjunction with automatic suppression. A broadly accepted equivalent design basis (to that for non-sprinklered occupancies) for using both sprinklers and vents together for hazard control (e.g., property protection, life safety, water usage, obscuration, etc.) has not been universally recognized." So where do we stand if the NFPA 204 notes that an accepted equivalent design basis for using sprinklers, vents and curtain boards together for hazard control is currently not available. Designers are strongly cautioned that use of venting with automatic sprinklers is an area of ongoing research to determine its benefit and effect in conjunction with automatic suppression. A broadly accepted equivalent design basis (to that for non-sprinklered occupancies) for using both sprinklers and vents together for hazard control has not been universally recognized." With the above noted concerns voiced by the NFPA 204 committee and the IBC and IFR blindly requiring venting, a serious dichotomy has existed for at least 40 years concerning the ability to control fire through the use of automatic roof vents and adequately sprinklered buildings. This dichotomy is further exacerbated with the use the latest sprinkler technology in the form of Early Suppression Quick Response (ESFR) sprinkler systems. Why are contractors so enthusiastically taking on these type of projects? Have a fire safe day! Regards Jim Jim Davidson Davidson Associates Fire Protection * Medical Gas * Code Consulting 302-994-9500 Fax:302-234-1781 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Chris Cahill Sent: Friday, November 05, 2010 12:46 PM To: [email protected] Subject: RE: smoke vents for retrofit I'd say it depends. If it was in full compliance with the Code before you add sprinklers I'd say no the sprinklers are above and beyond the MINIMUM of the Code. If it was not in compliance then maybe. I'd say it needs to be brought up to Code in all respects. Some scenarios require both sprinklers and smoke control, others just sprinklers. Look in Chapter 1 for applicability that I believe is what is the guiding Code section. If it is existing HPS and doesn't have smoke control I'd be first guessing it was not in compliance when built (or changed to HPS). Chris Cahill -----Original Message----- From: Matt Grise [mailto:[email protected]] Sent: Thursday, November 04, 2010 2:53 PM To: '[email protected]' Subject: smoke vents for retrofit If an existing building is retrofit with an area/density system to protect high piled storage, does it need to have smoke vents and draft curtains added as described in the IFC, or is that just new construction? I looked around in the IFC/IBC/IEBC books, but I could not find anything that would exempt the vents and curtains. Does anyone recall any way to avoid them (other than ESFR)? Matt Grisé PE*, LEED AP Sales Engineer Alliance Fire Protection *Licensed in KS & MO 913.888.0647 ph 913.888.0618 f 913.927.0222 cell www. AFPsprink.com _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
