Section 675IAC14-4.3-79. Section R408.2; openings for under-floor ventilation

   Make the following changes to Section R408.2:

(1) Delete the first two (2) sentences of R408.2 without substitution.

(2) Change Exception 1 to read as follows: Ventilation openings to the outdoors are not required if ventilation openings to the interior are provided.

(3) Amend Exception 5 as follows: Delete "Section N1102.1.7" and substitute "Chapter 11 of this code".

(4) Add Exception 6 to read as follows: 6. Ventilation openings are not required when the under-floor space is insulated in accordance with Chapter 11 of this code, the insulation materials comply with Sections R314 and R316 of this code and the ground surface is covered with an approved vapor retarder that extends to the exterior walls and all penetrations. The vapor retarder shall have a minimum thickness of 0.006 inch and shall be installed so that any joints are lapped at least 6 inches (152 mm). Mechanical ductwork shall be uninsulated and shall have no openings into the under-floor space. A hard surface pad with dimensions of at least 16 inches (407 mm) by 16 inches (407 mm), and an electrical receptacle shall be installed to allow for the installation of dehumidification equipment in the event of high humidity conditions in the under-floor spaces. Openings into conditioned space shall be permitted.

(5) Add Exception 7 to read as follows: 7. Ventilation openings are not required when the under-floor space is insulated in accordance with Chapter 11 of this code, the insulation materials comply with Sections R314 and R316 of this code and there is a concrete floor at least 2 inches (51 mm) thick installed on the ground surface of the under-floor space. A vapor retarder, at least 0.006 inch (.152 mm) thick and extending to the exterior walls and penetrations, shall be installed under the concrete floor. Conditioned air shall be circulated through the under-floor space at a rate of at least 1 cfm (10 m²) for each 50 square feet (1.02 L/s) of under-floor space.

(Fire Prevention and Building Safety Commission; 675 IAC 14-4.3-79; filed Jun 13, 2005, 3:00 p.m.: 28 IR 3274, eff 90 days after filing with the Secretary of State; filed Mar 6, 2008, 11:13 a.m.: 20080402-IR-675070483FRA; readopted filed Aug 4, 2011, 8:35 a.m.: 20110831-IR-675110254RFA)