MI Ice & Water Shield Reg Interpretation

lituani

Michigan building department regs state;
R905.2.7.1 Ice protection required on all eave edges to a point at least 24 inches inside the exterior wall line of the building. Ice/ Water shield or two layers of underlayment cemented together.
Exception: Detached accessory structures that contain no conditioned floor area.

For homes build in southeast Michigan (Oakland county), looking for input on three questions;
1)Having received conflicting interpretations of "at least 24 inches inside the exterior wall line", does reg intend you to measure 24" along the sloped roof, or from the vertical projection 2 feet inboard of the exterior wall?
2)Does anyone know whether this reg is independent of roof slope considerations, or has recently been modified for roof pitches?
3)Presumably this applies to unheated attached garage?
Appreciate any/all help!

Renegade

I'm in Idaho but can still help.
That reg basically is cut and paste mfr spec.
The 24" is a horizontal measurement from the exterior wall. The pitch will determine how many runs you need to get that 24" behind the wall. The steeper the pitch, the more you will need.
Ice /water is NOT required for unconditioned spaces, that would include unheated attached garages. That being said, most contractors will put it on that garage anyways because it is attached and a part of the house. If it is detached and unheated, there is no reason to waste the money on it.

apkole

We are a West Michigan residential roofing contractor, and I concur with Renegade. A few years ago a city inspector knocked back a roof for because we neglected to install I&W to an attached garage roof. Fortunately, the homeowner was acting as their own GC on this addition, and things got worked out.

To fully comply with code, you need to install enough I&W to hit that 24" requirement. Must be installed on the house and any attached structures. We even install on open porches, just in case a nitpicky inspector takes the time to actually get out of their vehicle and do their job.

The assumption is that at some point, any structure attached to the house might be enclosed and heated.

apkole

Huh, proof that we learn something new everyday. For an interesting read, compare this reg from the 2003 Michigan Residential Code to the 2006 (most current) code. Verrry interrresting.

2003 "Ice protection. In areas where the average daily temperature in January is 25 F (-4 C) or less . . . . yada yada yada"

2006 " Ice barrier. In areas where there has been a history of ice forming " per table yada yada yada


Upon further consideration, the change means little to Michigan roofing contractors. The ice and watershield requirement stands.