Washington Administrative Code › Title 51 - Enterprise Services, Department of (Building Code Council) › Chapter 51-11R - State Building Code adoption and amendment of the 2021 edition of the International Energy Conservation Code, Residential › Section 51-11R-40220 - Section R4022-Specific insulation requirements

Current through Register Vol. 24-14, July 15, 2024
R402.2 Specific insulation requirements.
In
				addition to the requirements of Section R402.1, insulation shall meet the
				specific requirements of Sections R402.2.1 through R402.2.11.
R402.2.1 Ceilings with attic spaces.
Where Section
				R402.1.3 would require R-60 in the ceiling or attic, installing R-49 over 100
				percent of the ceiling area requiring insulation shall satisfy the requirement
				for R-60 wherever the full height of uncompressed R-49 insulation extends over
				the wall top plate at the eaves. This reduction shall not apply to the
				insulation and fenestration criteria in Section R402.1.2 and the total UA
				alternative in Section R402.1.5.
R402.2.1.1 Loose insulation in attic spaces.
Open-blown or poured loose fill insulation may be used in attic spaces where
				the slope of the ceiling is not more than 3 feet in 12 and there is at least 30
				inches of clear distance from the top of the bottom chord of the truss or
				ceiling joist to the underside of the sheathing at the roof ridge.
R402.2.2 Reserved.
R402.2.3 Eave baffle.
For air-permeable insulation
				in vented attics, a baffle shall be installed adjacent to soffit and eave
				vents. Baffles shall maintain a net free area opening equal to or greater than
				the size of the vent. The baffle shall extend over the top of the attic
				insulation. The baffle shall be permitted to be any solid material. The baffle
				shall be installed to the outer edge of the
exterior wall
top
				plate so as to provide maximum space for attic insulation coverage over the top
				plate. Where soffit venting is not continuous, baffles shall be installed
				continuously to prevent ventilation air in the eave soffit from bypassing the
				baffle.
R402.2.4 Access hatches and doors.
Access hatches
				and doors from conditioned spaces to unconditioned spaces such as attics and
				crawl spaces shall be insulated to the same
R
-value required
				by Table R402.1.3 for the wall or ceiling in which they are installed.
EXCEPTION:
Vertical doors providing access from conditioned spaces
						  to unconditioned spaces that comply with the fenestration rents of Table
						  R.3.
R402.2.4.1 Access hatches and door insulation
				installation and retention.
Vertical or horizontal access hatches and
				doors from
conditioned spaces
to
unconditioned
				spaces
such as attics and crawl spaces shall be weatherstripped.
				Access that prevents damaging or compressing the insulation shall be provided
				to all equipment. Where loose fill insulation is installed, a wood framed or
				equivalent baffle or retainer, or dam shall be installed to prevent the
				loose-fill insulation from spilling into the living spaces, from higher to
				lower sections of the attic and from attics covering conditioned spaces to
				unconditioned spaces. The baffle or retainer shall provide a permanent means of
				maintaining the installed
R
-value of the loose fill
				insulation.
R402.2.5 Mass walls.
Mass walls, where used as a
				component of the
building thermal envelope
, shall be one of
				the following:
1. Above-grade walls of concrete block, concrete, insulated
				concrete form, masonry cavity, brick (but not brick veneer), adobe, compressed
				earth block, rammed earth, mass timber, or solid logs.
2. Any other wall having a heat capacity greater than or equal
				to 6 Btu/ft2 x °F (123
				kJ/m2 x K).
R402.2.6 Steel-frame ceilings, walls, and floors.
Steel-frame ceilings, walls, and floors shall comply with the
U
-factor requirements of Table R402.1.2.
R402.2.7 Floors.
Floor framing cavity insulation
				shall comply with one of the following:
1. Insulation shall be installed to maintain
			 permanent contact with the underside of the subfloor decking in accordance with
			 manufacturer instructions to maintain required
R
-value or
			 readily fill the available cavity space. Insulation supports shall be installed
			 so spacing is no more than 24 inches on center. Foundation vents shall be
			 placed so that the top of the vent is below the lower surface of the floor
			 insulation.
2. Floor framing cavity
			 insulation shall be permitted to be in contact with the top side of sheathing
			 separating the cavity and the unconditioned space below. Insulation shall
			 extend from the bottom to the top of all perimeter floor framing members and
			 the framing members shall be air sealed.
3. A combination of cavity and continuous
			 insulation shall be installed so that the cavity insulation is in contact with
			 the top side of the continuous insulation that is installed on the underside of
			 the floor framing separating the cavity and the unconditioned space below. The
			 combined
R
-value of the cavity and continuous insulation shall
			 equal the required
R
-value for floors. Insulation shall extend
			 from the bottom to the top of all perimeter floor framing members and the
			 framing members shall be air sealed.
EXCEPTIONS:
1. When foundation vents are not placed so that the top
						  of the vent is below the lower surface of the floor insulation, a permanently
						  attached baffle shall be installed at an angle of 30° from horizontal, to
						  divert air flow below the lower surface of the floor insulation.
2. Substantial contact with the surface being insulated
						  is not required in enclosed floor/ceiling assemblies containing ducts where
						  full
R
alue insulation is installed between the duct and the
						  exterior surface.
R402.2.8 Below-grade walls.
Below-grade exterior
				wall insulation used on the exterior (cold) side of the wall shall extend from
				the top of the below-grade wall to the top of the footing and shall be approved
				for below-grade use. Above-grade insulation shall be protected. Insulation used
				on the interior (warm) side of the wall shall extend from the top of the
				below-grade wall to the below-grade floor level and shall include R-5 rigid
				board providing a thermal break between the concrete wall and the slab.
R402.2.9 Slab-on-grade floors.
The minimum thermal
				resistance (
R
-value) of the insulation around the perimeter of
				unheated or heated slab-on-grade floors shall be as specified in Table
				C402.1.3. The insulation shall be placed on the outside of the foundation or on
				the inside of the foundation wall. The insulation shall extend downward from
				the top of the slab for a minimum distance as shown in the table or to the top
				of the footing, whichever is less, or downward to at least the bottom of the
				slab and then horizontally to the interior or exterior for the total distance
				shown in the table. A two-inch by two-inch (maximum) pressure treated nailer
				may be placed at the finished floor elevation for attachment of interior finish
				materials. Insulation extending away from the building shall be protected by
				pavement or by a minimum of 10 inches (254 mm) of soil.
R402.2.9.1 Heated slab-on-grade floors.
The entire
				area of a heated slab-on-grade floor shall be thermally isolated from the soil
				with a minimum of R-10 insulation. The insulation shall be an approved product
				for its intended use. If a soil gas control system is present below the heated
				slab-on-grade floor, which results in increased convective flow below the
				heated slab-on-grade floor, the heated slab-on-grade floor shall be thermally
				isolated from the sub-slab gravel layer. R-10 heated slab-on-grade floor
				insulation is required for all compliance paths.
R402.2.10 Masonry veneer.
Insulation shall not be
				required on the horizontal portion of the foundation that supports a masonry
				veneer.
Statutory Authority:
				  RCW
				    19.27A.020,
				  19.27A.045 and
				  chapters
				  19.27 and
				  34.05 RCW. 13-04-055, §
				  51-11R-40220, filed 2/1/13, effective
				  7/1/13.