FIRE PREVENTION AND BUILDING SAFETY COMMISSION
Interpretation by the Fire Prevention and Building Safety Commission
Title: Interpretation of675 IAC 18-1.6 , 2014 Indiana Mechanical Code, Table 403.3
Date: February 2, 2016
Purpose and Background: The purpose of this nonrule policy is to clarify the kitchen exhaust requirements listed in Table 403 of the Indiana Mechanical Code (IMC). Under the section of Table 403.3 with the heading "Private dwellings, single and multiple", Kitchens are allowed to have intermittent exhaust per footnote "f", but footnote "b" listed after the word "Kitchens" refers to Section 403.2.1, item 3, which prohibits any recirculation of the air at any time, thereby requiring continuous exhaust and make-up air. Footnote "b" is also indicated in Table 403.1 for commercial food service kitchens, thus the application of the footnote to dwelling unit kitchens appears inappropriate for dwelling unit kitchens permitted to have intermittent exhaust. In Indiana, residential kitchen exhaust fans in a dwelling unit are often designed to run intermittently in accordance with footnote "f". It would be impossible to continuously exhaust all air in accordance with Section 403.2.1, item 3, when the exhaust fan is operated intermittently.
The previous version of the IMC, based upon the 2006 International Mechanical Code listed the words "intermittent" and "continuous" within the body of the Table and referenced footnote "g", which read "Transfer air permitted in accordance with Section 403.2.2.". Section 403.2.2 specifically allows transfer air to be used as make-up air for kitchens. Under the 2014 IMC, dwelling units are permitted to use natural ventilation in a number of cases under Section 401.2, as amended, and Section 402. Many kitchens are open to other living spaces and design of a residential HVAC system to meet the same code requirement as a commercial kitchen is neither practical, nor did the Commission contemplate the fiscal impact of such a requirement when adopting the 2014 IMC.
Interpretation: The Commission hereby interprets Table 403.3 as follows: Under the heading "Private dwellings, single and multiple" in the listing for Kitchens, Footnote "b" is inconsistent with intermittent kitchen exhaust typical in dwelling units and should be disregarded in the design of dwelling unit kitchens meeting the intermittent exhaust requirements of Table 403.3. No variance is required under this section for a dwelling unit kitchen exhaust fan complying with footnote "f" for 100 cfm fan operating intermittently. Where a continuous exhaust fan is designed for a dwelling unit kitchen, the requirement in Table 403.3 for 25 cfm is absolute and footnote "b" is assumed to have been met with a 25 cfm continuous exhaust, regardless of the size of the kitchen and proximity to adjacent communicating spaces. Transfer air is permitted to be used as make-up air in accordance with Section 403.2.2.
Posted: 06/15/2016 by Legislative Services Agency
DIN: 20160615-IR-675160229NRAComposed: Nov 01,2016 2:15:02AM EDTA PDF version of this document.
