Interpretation #7790

Published July 18, 2016

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Original Request

Code Version
2014
Code
BUILDING
Code Description
Chapter
Section
2508
Topic
Soffit board using 24" centers

Question

Is it the intent of the FBC, as it references GA-216 in Table 2508.1 (GA-216 specifically prohibits the use of 1/2" Soffit Board to be installed to trusses 24"OC), to prohibit the use of 1/2" Soffit Board on 24" OC in exterior installations? Could this be done as described if designed by a Florida Registered Engineer?

Answer Published 07/18/2016 at 10:31 AM

"Gypsum Board shall not be used where there will be direct
exposure to water or continuous high humidity." Per 2508.2.
An alternate is to use gypsum sheathing installed per ASTM
C 1280. So the answer is "yes" it is prohibited.

Commentary

It is the intent to prohibit Gypsum Board outdoors as is regulated by GA-216. 2508.2 Soffit Board is usually a form of Gypsum Sheathing. Gypsum Sheathing is installed per ASTM C 1280 and the manufacturer's approved instructions. Maximum framing spacing regardless of wind load must comply with manufacturer's installation instructions. If a Product Approval or ICC Evaluation Report is not available regarding wind loads, an engineer can design the Assembly that includes the Soffit Board.