Prescriptive Worksheet Both Zones 2015 modTable R402.1.1 Footnotes
For SI: 1 foot .= 304.8 mm, ci .= continuous insulation, int .= intermediate framing.
a R-values are minimums. U-factors and SHGC are maximums. When insulation is installed in a cavity which is
less than the label or design thickness of the insulation, the compressed R-value of the insulation from
Appendix Table A101.4 shall not be less than the R-value specified in the table.
b The fenestration U-factor column excludes skylights. The SHGC column applies to all glazed fenestration.
"10/15/21.+TB" means R-10 continuous insulation on the exterior of the wall, or R-15 on the continuous
insulation on the interior of the wall, or R-21 cavity insulation plus a thermal break between the slab and the
basement wall at the interior of the basement wall. "10/15/21.+TB" shall be permitted to 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 wall. "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. "TB" means thermal break between floor slab and basement
wall.
d R-10 continuous insulation is required under heated slab on grade floors. See R402.2.9.1.
e There are no SHGC requirements in the Marine Zone.
f Reserved.
g Reserved.
h Reserved.
'The second R-value applies when more than half the insulation is on the interior of the mass wall.
Reserved.
k For single rafter- or joist -vaulted ceilings, the insulation may be reduced to R-38.
Reserved.
m Int. (intermediate framing) denotes standard framing 16 inches on center with headers insulated with a
minimum of R-10 insulation.
Table R402.1.3 Footnote
a Nonfenestration U-factors shall be obtained from measurement, calculation or an approved source or as
specified in Section R402.1.3.