Mich. Comp. Laws § 125.1513g

Sec. 13g. (1) Except as otherwise provided by the Michigan rehabilitation code for existing buildings, where an alteration affects the accessibility to, or contains, an area of primary function, the route to the primary function area shall be accessible. The accessible route to the primary function area shall include toilet facilities and drinking fountains serving the area of primary function. The costs of providing the accessible route are not required to exceed 20% of the total costs of the alterations affecting the area of primary function. (2) As used in this section, "alteration" and "primary function" mean those terms as defined in the Michigan rehabilitation code for existing buildings or as otherwise provided by the director by rule.