2018 IBC. 2304.12.2.6

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Author Message Dave Metzger Senior Member Username: davemetzger Post Number: 728 Registered: 07-2001 Posted on Monday, June 25, 2018 - 03:55 pm:    I have a question about a new provision in the 2018 IBC. 2304.12.2.6 states: 2304.12.2.6 Ventilation beneath balcony or elevated walking surfaces. Enclosed framing in exterior balconies and elevated walking surfaces that are exposed to rain, snow, or drainage from irrigation shall be provided with openings that provide a net free cross ventilation area not less than 1/150 of the area of each separate space. I read this as being applicable to exterior balconies and elevated walking surfaces that are exposed to rain, snow, or drainage from irrigation, and that have enclosed framing. The point is that “exposed” refers to exterior balconies and elevated walking surfaces, and not to the framing; and that “enclosed framing” is applicable both to balconies and to elevated walking surfaces. However, I am in contact with someone who interprets the paragraph to mean that “exposed” applies to “enclosed framing in exterior balconies” “and elevated walking surfaces”, instead of “exterior balconies and elevated walking surfaces”. I do not agree with this because it is a logical inconsistency, i.e. framing cannot be both enclosed and exposed. Would you agree that my understanding is consistent with the intent of this provision? And that the following is a correct reading of the intent of this provision (comma added after the words “framing” and “irrigation”)? “Enclosed framing, in exterior balconies and elevated walking surfaces that are exposed to rain, snow, or drainage from irrigation, shall be provided with openings that provide a net free cross ventilation area not less than 1/150 of the area of each separate space.” Greta Eckhardt Senior Member Username: gretaeckhardt Post Number: 74 Registered: 08-2013 Posted on Monday, June 25, 2018 - 04:04 pm:    I agree, Dave, and also note that the verb associated with the framing would be the singular "is", whereas in the actual text of the Code, the verb that precedes the word "exposed" is the plural "are." Brian Payne, AIA Senior Member Username: brian_payne Post Number: 151 Registered: 01-2014 Posted on Monday, June 25, 2018 - 04:13 pm:    Short Answer: I agree. Since the section is entitled "Ventilation beneath balcony or elevated walking surface", it would make sense that you would only need to ventilate framing if it was in fact otherwise enclosed. The use of "or" makes it plain that both the elevated surfaces and the balconies that are enclosed would need this ventilation. Am i missing something? John Bunzick, CCS, CCCA, LEED AP Senior Member Username: bunzick Post Number: 1745 Registered: 03-2002 Posted on Monday, June 25, 2018 - 04:40 pm:    Plus, if the framing is already exposed, what would it mean to ventilate? What would be ventilated? I would think the point is to allow enclosed spaces that may have high humidity or incidental leaking to dry out between wetting events. Otherwise, it makes no sense. Steven Bruneel, AIA, CSI-CDT, LEED-AP, EDAC Senior Member Username: redseca2 Post Number: 649 Registered: 12-2006 Posted on Monday, June 25, 2018 - 05:49 pm:    I agree with your interpretation. There have been balcony failures with loss of life due to dry rot that I believe triggered this requirement. In California Wild Fire zones the code then walks it back: SECTION 706A VENTS 706A.1 General. Where provided, ventilation openings for enclosed attics, enclosed eave soffit spaces, enclosed rafter spaces formed where ceilings are applied directly to the underside of roof rafters, and underfloor ventilation shall be in accordance with Section 1203 and Sections 706A.1 through 706A.3 to resist building ignition from the intrusion of burning embers and flame through the ventilation open- ings. 706A.2 Requirements. Ventilation openings for enclosed attics, enclosed eave soffit spaces, enclosed rafter spaces formed where ceilings are applied directly to the underside of roof rafters, and underfloor ventilation openings shall be fully covered with metal wire mesh, vents, other materials or other devices that meet the following requirements: 1. The dimensions of the openings therein shall be a mini- mum of 1 16 -inch (1.6 mm) and shall not exceed 1 8 -inch (3.2mm). 2. The materials used shall be noncombustible. Exception: Vents located under the roof covering, along the ridge of roofs, with the exposed surface of the vent covered by noncombustible wire mesh, may be of combustible materials. 3. The materials used shall be corrosion resistant Guest (Unregistered Guest) Unregistered guest Posted on Tuesday, June 26, 2018 - 12:01 pm:    I agree with Dave's understanding of the code, and believe it is in response to events like what happened at Berkeley a few years ago (http://discus.4specs.com/discus/messages/4254/7700.html) I don't, however, understand Steven's point that the requirements for California Wild Fire zones walks back or contradicts the ventilation requirement. The ventilation requirement is about a net free area, and the wild fire zones requirement is about the size of the openings and the material creating the openings. I believe it is possible to achieve the appropriate net free area with small enough openings in the right material to comply with both provisions.