STATE BUILDING CODE INTERPRETATION NO. 07-04

CODE:	2006 International Residential Code
SECTION:	M1501.1
QUESTION:	The 2006 edition of IRC Section M1501.1 allows whole house ventilation-type attic fans to terminate into the attic space of a private dwelling. This is consistent with code language found in the 2006 edition of IMC Section 501.2 except the State has amended this section to replace "whole-house ventilation-type attic fans", to be "whole-house cooling attic fans". Was this language also supposed to be placed in IRC Section M1501.1? This appears to be in conflict with the Washington State Ventilation and Indoor Air Quality Code Section 302.3.4 that requires all ventilation ducts to terminate outside the building.
ANSWER:	Yes, this section was intended to be amended to be consistent with IMC Section 501.2. It is not the intent of these sections to allow a whole-house ventilation system to discharge into the attic. The Washington State Ventilation and Indoor Air Quality Code still governs the installation and exhaust of whole-house ventilation systems. The intent of the IRC/IMC language is to allow a circulation fan in the attic that is generally used in warm, dry climates in the evenings to pull in cooler outdoor air. The IMC was amended to try to eliminate the conflict in terms.
SUPERSEDES:	None
REQUESTED BY:	City of Bellevue