Michigan Residential Code Rules That Apply to Roof Repairs

Michigan writes its building codes into state rules under the Stille-DeRossett-Hale Single State Construction Code Act. Section 125.1504 of that act tells the state to build its code from the International Code Council's model codes, including the International Residential Code, "with amendments, additions, or deletions as the director determines appropriate." For one- and two-family homes and townhouses up to three stories, the result is the Michigan Residential Code, and Section R101.2 lists "repair" by name among the work it covers.

The edition in force for houses is the 2015 Michigan Residential Code. The state finished rules that would have moved to a code based on the 2021 IRC, set to take effect on August 29, 2025, but a court's stipulated order paused them. LARA's Bureau of Construction Codes says that while the order remains in place, "the 2015 versions of the IRC and residential provisions of the IECC standards currently adopted, in part, by each rule set will remain valid and in effect." The history of those editions is covered in its own article.

Section R903.1 is the general duty: roof assemblies "shall be designed and installed in accordance with this code and the approved manufacturer's instructions such that the roof assembly shall serve to protect the building or structure." Section R904.1 repeats the point for roof coverings, and R905.1 says roof coverings "shall be applied in accordance with the applicable provisions of this section and the manufacturer's installation instructions."

That is why, in Michigan, the instructions printed on a shingle bundle are not a suggestion. They are part of what the code requires. On a repair, that brings in details the code itself never spells out: where the nail line sits on that particular shingle, how far shingles must lap into a valley, and when shingles must be hand-sealed. GAF's Timberline instructions, for example, say that if shingles are installed during prolonged cold periods they must be hand sealed, and they set a four-nail standard pattern with a six-nail enhanced pattern that some local codes require.

Section R905.2 is the asphalt shingle section, and its numbers are the ones that come up on almost every shingle repair. A repair that misses them is below the legal minimum, not just below best practice.

Section R908 applies when a roof covering is recovered or replaced, and large repairs often end up here. R908.1 says materials and methods used for re-covering or replacing a roof covering shall comply with Chapter 9. R908.2 says the structure has to carry the new roof and the material and equipment loads of installing it.

Section R908.3 defines replacement as removing existing layers "down to the roof deck," with one exception: an ice barrier membrane already adhered to the deck may stay and be covered with another layer of ice barrier. Section R908.3.1.1 forbids a re-cover where the existing roof is water soaked or deteriorated, where it is slate, clay, cement or asbestos-cement tile, or where the roof already has two or more applications of any covering. That is the two-layer limit you hear about. Stellar won't warranty a shingle overlay and talks people out of them even where the code would allow one.

Two more sections matter on repairs that touch flashing. R908.5 says existing "flashings, edgings, outlets, vents or similar devices that are a part of the assembly shall be replaced where rusted, damaged or deteriorated." R908.6 says flashings "shall be reconstructed in accordance with approved manufacturer's installation instructions." In practice, reusing a rusted step flashing or a cracked vent hood under new shingles is not a shortcut the code allows.

The building official enforces the code. Section R104.1 gives that official authority to "render interpretations of this code," and Section R113.1 makes it unlawful to "erect, construct, alter, extend, repair" a regulated building in conflict with the code. Nobody inspects a small unpermitted repair, but the standard still applies, and a home inspector or adjuster may measure the work against it later.

For a homeowner, the practical use of all this is in the estimate and the conversation. Ask the roofer which of these sections the repair touches and how the work meets them. A good contractor answers plainly and names the manufacturer whose instructions they follow. This page describes what the code says, not how it applies to your house: for that, confirm with your local building department.