2017 Oregon Residential Specialty Code
Energy Efficiency – Prescriptive Envelope Requirement
Reference Tables
TABLE N1101.1 (1) PRESCRIPTIVE ENVELOPE REQUIREMENTS (a)
Wall insulation-above grade
Wall insulation-above grade (e)
R-30 Rafter of R-
30 A (g,h) Scissor
Truss
Window area limitation (j,k,)
Exterior doors w/ > 2.5 ft ² glazing
(n)
Forced air duct insulation
For SI: 1 inch = 25.4 mm, 1 square foot = 0.0929 m², 1 degree = 0.0175 rad.
a. As allowed in Section N1104.1, thermal performance of a component may be adjusted provided that overall heat loss does not
exceed the total resulting from conformance to the required U-value standards. Calculations to document equivalent heat loss shall
be performed using the procedure and approved U-values contained in Table N1104.1 (1).
a. R-values used in this table are nominal for the insulation only in standard wood framed construction and not for the entire assembly.
b. Wall insulation requirements apply to all exterior wood framed, concrete or masonry walls that are above grade. This includes
cripple walls and rim joist areas. Nominal compliance with R-21 insulation and Intermediate Framing (N1104.5.2) with insulated
headers.
c. The wall component shall be a minimum solid log or timber wall thickness of 3.5 inches (90 mm).
d. Below-grade wood, concrete or masonry walls include all walls that are below grade and do not include those portions of such wall
that extend more than 24 inches (609.6 mm) above grade.
e. Insulation levels for ceilings that have limited attic/rafter depth such as dormers, bay windows or similar architectural features
totaling not more than 150 square feet (13.9 m²) in area may be reduced to not less than R-21. When reduced, the cavity shall be
filled (except for required ventilation spaces). R-49 insulation installed to minimum 6-inches depth at the top plate at exterior of
structure to achieve U-factor.
f. Vaulted ceiling surface area exceeding 50 percent of the total heated space floor area shall have a U-factor no greater than U-0.026
(equivalent to R-38 rafter or scissor truss with R-38 advanced framing).
g. A= Advanced frame construction. See Section N1104.6
h. Heated slab interior applies to concrete slab floors (both on and below grade) that incorporate a radiant heating system within the
slab. Insulation shall be installed underneath the entire slab.
i. Sliding glass doors shall comply with window performance requirements. Windows exempt from testing in accordance with
Section NF1111.2, Item 3 shall comply with window performance requirements if constructed with thermal break aluminum or wood,
or vinyl, or fiberglass frames and double-pane glazing with low-emissivity coatings of 0.10 or less. Buildings designed to incorporate
passive solar elements may include glazing with a U-factor greater than 0.35 by using Table N1104.1 (1) to demonstrate
equivalence to building envelope requirements.
j. Reduced window area may not be used as a trade-off criterion for thermal performance of any component.
k. Exception: Table N1101.1 (2), Envelope Measure 6: calculation allows baseline case 15 percent of total wall area as window when
design case utilizes window area of less than 15 percent.
l. Skylight area installed at 2 percent or less of total heated space floor area shall be deemed to satisfy this requirement with vinyl,
wood or thermally broken aluminum frames and double-pane glazing with low-emissivity coatings. Skylight U-factor is tested in the
20 degree (0.35 rad) overhead plane in accordance with NFRC standards.
m. A maximum of 28 square feet (2.6 m²) of exterior door area per dwelling unit can have a U-factor of 0.54 or less.
n. Glazing that is either double pane with low-e coating on one surface, or triple pain shall be deemed to comply with this U-0.40
requirement.
