601.1 General: This chapter establishes design criteria
in terms of prescribed requirements for building construction.
The provisions of this chapter are applicable to all
Group R Occupancies. Occupancies shall comply with all the
requirements of Chapter 5 except for the modifications herein
specified.
For wood frame assemblies, the building envelope
requirements of this chapter may be met by installing one of
the prescriptive packages in Table 6-1 or 6-2. Installed
components shall meet the requirements of section 602.
Compliance with nominal R-Values shall be demonstrated for the
thermal resistance of the added insulation in framing cavities
and/or insulated sheathing only and shall not include the
thermal transmittance of other building materials or air
films, but shall permit interruption by occasional framing
members. Other than wood frame assemblies with continuous
insulation uninterrupted by framing shall also be allowed to
comply with nominal R-values.
For metal frame assemblies, compliance shall be
demonstrated in accordance with Chapter 4 or Chapter 5 based
on the assemblies in Chapter 10. Compliance with nominal
R-values is not allowed, unless the full nominal R-value of
the insulation is installed either inside or outside of the
framing and is uninterrupted by framing.
EXCEPTION:
Group R-1 and R-2 Occupancy buildings may use a maximum area weighted average U-factor for components not
exceeding those prescribed in Paths III and V in Table 6-1 or Paths IV and VI in Table 6-2.