Building Design By Prescriptive Requirements Approach
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 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.
SECTION 602 - BUILDING ENVELOPE REQUIREMENTS FOR GROUP R OCCUPANCY
602.1 Roof/Ceiling: Ceilings below vented attics and single-rafter, joist- vaulted ceilings shall be insulated to not less than the nominal R-value specified for ceilings in Table 6-1 or 6-2 as applicable.
602.2 Exterior Walls Both Above and Below Grade: Above grade exterior walls shall be insulated to not less than the nominal R-value specified in Table 6-1 or 6-2 as applicable. The following walls should be considered to meet R-21 without additional documentation:
- 2 x 6 framed and insulated with R-21 fiberglass batts.
- 2 x 4 framed and insulated with R-15 fiberglass batts plus R-4.0 foam sheathing.
- 2 x 4 framed and insulated with R-13 fiberglass batts plus R-5.0 foam sheathing.
602.3 Exterior Walls (Below Grade): Below grade exterior walls surrounding conditioned space shall be insulated to not less than the nominal R-value specified for below grade walls in Table 6-1 or 6-2 as applicable.
602.4 Slab-on-Grade Floors: Slab-on-grade floors shall be insulated along their perimeter to not less than the nominal R-values specified for slab-on-grade floors in Table 6-1 or 6-2 as applicable. Slab insulation shall be installed in compliance with Section 502.1.4.8. See Chapter 5, Section 502.1.4.9, for additional requirements for radiant slab heating.
602.5 Floors Over Unconditioned Space: Floors over unconditioned spaces, such as vented crawl spaces, unconditioned basements and parking garages shall be insulated to not less than the nominal R-value shown for floors over unconditioned spaces in Table 6-1 or 6-2.
602.6 Exterior Doors: Doors shall comply with Sections 602.6.1 and 602.6.2.
EXCEPTIONS:
- Glazed doors whose area and U-factor are included in the calculations for compliance with the requirements for glazing in Section 602.7 shall be exempt from the door U-factor requirements prescribed in Table 6-1 or 6-2.
- One unlabeled or untested exterior swinging door with the maximum area of 24 square feet may be installed per unit for ornamental, security or architectural purposes. Products using this exception shall not be included in either the U-factor or glazing area calculation requirements.
602.6.1 Exterior Door Area: For half-lite and full-lite doors, the glazing area shall be included in calculating the allowed total glazing area in Section 602.7.1. Single glazing used for ornamental, security or architectural purposes shall be calculated using the exception to Section 602.7.2.
602.6.2 Exterior Door U-Factor: **CAM 403; Website NFRC** Doors, including fire doors, shall have a maximum area weighted average U-factor not exceeding that prescribed in Table 6-1 or 6-2.
602.7.1 Glazing Area: The total glazing area as defined in Chapter 2 shall not exceed the percentage of gross conditioned floor area specified in Table 6-1 or 6-2. This area shall also include any glazing in doors.
602.7.2 Glazing U-Factor **CAM 403; Website NFRC**: The total glazing area as defined in Chapter 2 shall have an area weighted average U-factor not to exceed that specified in Table 6-1 or 6-2. U-factors for glazing shall be determined in accordance with Section 502.1.5. These areas and U-factors shall also include any doors using the exception of Section 602.6.
If the U-factors for all vertical and overhead glazing products are below the appropriate U-factor specified, then no calculations are required. If compliance is to be achieved through an area weighted calculation, then the areas and U-factors shall be included in the plans submitted with a building permit application. **CAM 303**
EXCEPTION: Single glazing for ornamental, security or architectural purposes and double glazed garden windows with a wood or vinyl frame shall be exempt from the U-factor calculations but shall have its area tripled and shall be included in the percentage of the total glazing area as allowed for in Table 6-1 or 6-2. The maximum area (before tripling) allowed for the total of all single glazing and garden windows is 1% of the floor area.
602.8 Air Leakage for Group R Occupancy: The minimum air leakage control measures shall be as specified in Section 502.4 as applicable.
SECTION 603 - BUILDING MECHANICAL SYSTEMS FOR GROUP R OCCUPANCY **CAM 415**
603.1: Group R Occupancies that are space heated by air-to-air, ground-to-air or water-to-air heat pumps shall comply with Table 6-1 or 6-2. System sizing shall be determined by an analysis consistent with Section 503.2 **Form Equipment Sizing** of this Code, or, when approved by the building official, Chapter 9. All mechanical equipment efficiencies and service water heating system efficiencies shall comply with standards as stated in Sections 503 and 504 of this Code.
SECTION 604 -- RESERVED
SECTION 605
-- LIGHTING
Lighting shall comply with Section 505
TABLE 6-1 - PRESCRIPTIVE REQUIREMENTS0,1 FOR GROUP R OCCUPANCY CLIMATE ZONE 1
**CAM
303, CAM
303A**
TABLE 6-2 - PRESCRIPTIVE REQUIREMENTS0,1 FOR GROUP R OCCUPANCY CLIMATE ZONE 2
TABLE 6-3 - RESERVED
TABLE 6-4 - RESERVED
TABLE 6-5 - RESERVED
TABLE 6-6 - RESERVED
