Mich. Admin. Code R. 408.31063
Rule 1063. Insulation and fenestration criteria. Table R402.1.1 of the code is amended to read as follows:
TABLE R 402.1.1 INSULATION AND FENESTRATION REQUIREMENTS BY COMPONENTa
CLIMATE ZONE | FENESTRATION U-FACTOR | SKYLIGHTb U-FACTOR | CEILING R-Value | WOOD FRAME WALL R-VALUE | MASS WALL R-VALUEg | FLOOR R-VALUE | BASEMENTc WALL R-VALUE | SLAB d R-VALUE AND DEPTH | CRAWL SPACEc WALL R-VALUE |
5A | 0.32 | 0.55 | 38 | 20 or 13 + 5f | 13/17 | 30e | 10/13 | 10, 2ft | 15/19 |
6A | 0.32 | 0.55 | 49 | 20 or 13 + 5f | 15/20 | 30e | 15/19 | 10, 4ft | 15/19 |
7 | 0.32 | 0.55 | 49 | 20 or 13 + 5f | 19/21 | 38e | 15/19 | 10, 4ft | 15/19 |
a. R-values are minimums. U-factors are maximums. When insulation is installed in a cavity that is less than the label or design thickness of the insulation, the installed R-value of the insulation shall not be less than the R-values specified in the table.
b. The fenestration U-factor column excludes skylights.
c. "15/19" means R-15 continuous insulation on the interior or exterior of the home or R-19 cavity insulation at the interior of the basement wall. "15/19" may be met with R-13 cavity insulation on the interior of the basement wall plus R-5 continuous insulation on the interior or exterior of the home. "10/13" means R-10 continuous insulation on the interior or exterior of the home or R-13 cavity insulation at the interior of the basement wall.
d. R-5 shall be added to the required slab edge R-values for heated slabs.
e. Or insulation sufficient to fill the framing cavity, R-19 minimum.
f. First value is cavity insulation, second is continuous insulation or insulated siding, so "13 + 5" means R-13 cavity insulation plus R-5 continuous insulation or insulated siding. If structural sheathing covers 40 % or less of the exterior, continuous insulation R-value may be reduced by no more than R-3 in the locations where structural sheathing is used to maintain a consistent total sheathing thickness.
g. The second R-value applies when more than half the insulation is on the interior of the mass wall.
Mich. Admin. Code R. 408.31063