Important Changes to the PA Construction Code Act (Act 45) of 1999 | Vol. 2: The 2009 International Mechanical Code (IMC)

The following are some key mechanical code changes that engineers, architects and owners should know about in order to minimize negative impacts to your current or future projects.

Section 306.5

Addresses the accessibility of equipment on rooftops and outlines when permanent ladders must be installed to make equipment readily accessible for service. This section states that access shall not require climbing over obstacles over 30 inches high and the 2009 revision identifies parapet walls as such an obstacle.

Section 403

Changes the means for calculating the outdoor air requirements to conform with ASHRAE Standard 62-2007. This a significant revision that may increase the amount of outdoor air required compared to the 2006 IMC.

Section 506.4.2

Includes additional requirements for Type II exhaust outlets, which can restrict where a fan or discharge outlet from a Type II hood can be placed.

For more information or questions about these changes, review the ECC on the International Code Council (ICC) website or contact Douglas C. Barnhart, PE at (717) 845-7654 or

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