Return to Blog

Michigan Residential Code Book Errors and Conflicts

In the 2015 Michigan Residential Code book some mistakes were found. The following are errors and conflicts that have been identified at this point. The Bureau of Construction Codes (BCC) has reviewed these issues. The Director of Department of Licensing and Regulatory Affairs (LARA) has delegated the authority to make, and has approved, the following determinations which are binding on all enforcing agencies.

You can download the official document at the LARA website.

Stair Geometry

In the Michigan Residential Code Section R311.7.4.1 Riser height and Section R311.7.4.2 Tread depth are the correct requirements for stair geometry and they are the promulgated state rules consistent with MCL 125.1513d.  These provisions shall replace the provisions in Sections R311.7.5.1 and R311.7.5.2 respectively; however the exceptions in R311.7.5.1 are still valid.

Note: 8 ¼” max. rise and 9” min. tread are still the MI code.

Vapor Retarders

There are 2 sections on vapor retarders in the 2015 Michigan Residential Code, R601.3 and R702.7.  It has been determined by the department that section R601.3 is the section that is to be enforced by all enforcing agencies.

Figure R507.2.1(2) was obviously corrupted during the publication of the rules and was not noticed until it was published by the International Code Council.  The figure that must be used by all enforcing agencies is now provided.

Figure R507.2.1(2)


Carbon Monoxide Detector Location

MRC section R315 does not provide the location of the carbon monoxide detectors.  The location of these devices is found in the 1972 PA 230 section 4f, MCL 125.1504f:

A carbon monoxide device shall be located in the vicinity of the bedrooms, which may include 1 device capable of detecting carbon monoxide near all adjacent bedrooms.

Duct Construction

The Michigan Residential Code (MRC) Sections N1103.2.3 and M1601.1.1 conflict regarding the use of building framing cavities for plenums.  To resolve the conflict we look at the definition of “cost effective” in MCL 125.1502a(p), and MCL 125.1504(3)(f) and (g).

The conflict is resolved in favor of M1601.1.1 as MRC Section M1601 is the definitive section on duct construction.  This decision is based on MRC Section R102.1 (Where there is a conflict between a general requirement and a specific requirement, the specific requirement shall be applicable.)

Combustible Insulation 

R302.13 is the language that is promulgated by the department and is the language that must be used.  Section R302.14 shall treated as if it was deleted which was the intent.

Roof Loading Data Sheet

Figure 802.10.1 under Exposure Factor C the designation should be B C and D to be consistent with the ASCE 7-10 standard. The text for the exposures is correct but when A was deleted to be consistent with standard an auto correct function relabeled the remaining exposures A, B and C. This was not caught before publication. If the text is used for providing the requested information and A, B and C designation replaced with B. C and D respectively the information will be correct.



Return to Blog