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-40241 - Table R402.4.1.1-Air barrier and insulation installation

Current through Register Vol. 24-14, July 15, 2024
TABLE R402.4.1.1
AIR BARRIER, AIR SEALING AND INSULATION
				INSTALLATIONa
COMPONENT
AIR BARRIER CRITERIA
INSULATION CRITERIA
General requirements
A continuous air barrier shall be installed in the
						  building envelope.
Breaks or joints in the air barrier shall be
						  sealed.
Air-permeable insulation shall not be used as a sealing
						  material.
Cavity insulation installation
All cavities in the thermal envelope shall be filled
						  with insulation. The density of the insulation shall be at the manufacturers'
						  product recommendation and said density shall be maintained for all volume of
						  each cavity. Batt type insulation will show no voids or gaps and maintain an
						  even density for the entire cavity. Batt insulation shall be installed in the
						  recommended cavity depth. Where an obstruction in the cavity due to services,
						  blocking, bracing or other obstruction exists, the batt product will be cut to
						  fit the remaining depth of the cavity. Where the batt is cut around
						  obstructions, loose fill insulation shall be placed to fill any surface or
						  concealed voids, and at the manufacturers' specified density. Where faced batt
						  is used, the installation tabs must be stapled to the face of the stud. There
						  shall be no compression to the batt at the edges of the cavity due to inset
						  stapling installation tabs.
Insulation that upon installation readily conforms to
						  available space shall be installed filling the entire cavity and within the
						  manufacturers' density recommendation.
Ceiling/attic
The air barrier in any dropped ceiling/soffit shall be
						  aligned with the insulation and any gaps in the air barrier sealed.
Access openings, drop down stair or knee wall doors to
						  unconditioned attic spaces shall be sealed.
The insulation in any dropped ceiling/soffit shall be
						  aligned with the air barrier.
Batt insulation installed in attic roof assemblies may
						  be compressed at exterior wall lines to allow for required attic
						  ventilation.
Walls
The junction of the foundation and sill plate shall be
						  sealed. The junction of the top plate and top of exterior walls shall be
						  sealed. Knee walls shall be sealed.
Cavities within corners and headers of frame walls
						  shall be insulated by completely filling the cavity with a material having a
						  thermal resistance of R-3 per inch minimum. Exterior thermal envelope
						  insulation for framed walls shall be installed in substantial contact and
						  continuous alignment with the air barrier.
Windows, skylights and doors
The space between window/door jambs and framing and
						  skylights and framing shall be sealed.
Rim joists
Rim joists shall include an exterior air
						  barrierb.
The junctions of the rim board to the sill plate and
						  the rim board and the subfloor shall be air sealed.
Rim joists shall be insulated so that the insulation
						  maintains permanent contact with the exterior rim
						  boardb.
Floors (including above garage and cantilevered
						  floors)
The air barrier shall be installed at any exposed edge
						  of insulation.
Floor framing cavity insulation shall be installed to
						  maintain permanent contact with the underside of subfloor decking or floor
						  framing cavity insulation shall be permitted to be in contact with the topside
						  of sheathing or continuous insulation installed on the underside of floor
						  framing and extend from the bottom to the top of all perimeter floor framing
						  members.
Basement, crawl space, and slab foundations
Exposed earth in unvented crawl spaces shall be covered
						  with a Class I, black vapor retarder with overlapping joints taped.
Crawl space insulation, where provided instead of floor
						  insulation, shall be installed in accordance with Section R402.2.10.
Penetrations through concrete foundation walls and
						  slabs shall be air sealed.
Class I vapor retarders shall not be used as an air
						  barrier on below-grade
walls
and shall be installed in
						  accordance with Section R702.7 of the
International Residential
						  Code
.
Conditioned basement foundation wall insulation shall
						  be installed in accordance with Section R402.2.8.
Slab on grade floor insulation shall be installed in
						  accordance with Section R402.2.10.
Shafts, penetrations
Duct and flue shafts to exterior or unconditioned space
						  shall be air sealed.
Utility penetrations of the air barrier shall be
						  caulked, gasketed, or otherwise sealed and shall allow for expansion and
						  contraction of materials and mechanical vibration.
Insulation shall be fitted tightly around utilities
						  passing through shafts and penetrations in the building thermal envelope to
						  maintain required
R
-value.
Narrow cavities
Narrow cavities, of an inch or less, not able to be
						  insulated, shall be air sealed.
Batts in narrow cavities shall be cut to fit and
						  installed to the correct density without any voids or gaps or compression, or
						  narrow cavities shall be filled by insulation that on installation readily
						  conforms to the available cavity space.
Garage separation
Air sealing shall be provided between the garage and
						  conditioned spaces.
Insulated portions of the garage separation assembly
						  shall be installed in accordance with Sections R303 and R402.2.8.
Recessed lighting
Recessed light fixtures installed in the building
						  thermal envelope shall be air sealed in accordance with Section
						  R402.4.3.
Recessed light fixtures installed in the building
						  thermal envelope shall be air tight and IC rated and shall be buried or
						  surrounded with insulation.
Plumbing, wiring, or other obstructions
All holes created by wiring, plumbing, or other
						  obstructions in the air barrier assembly shall be air sealed.
Batt insulation shall be cut neatly to fit around
						  wiring and plumbing in exterior walls. There shall be no voids or gaps or
						  compression where cut to fit. Insulation that on installation readily conforms
						  to available space shall extend behind piping and wiring. Insulation shall be
						  installed to fill the available space and surround wiring, plumbing, or other
						  obstructions, unless the required
R
-value can be met by
						  installing insulation and air barrier systems completely to the exterior side
						  of the obstructions.
Shower/tub on exterior wall
The air barrier installed at exterior walls adjacent to
						  showers and tubs shall separate the wall from the showers and tubs.
Exterior walls adjacent to showers and tubs shall be
						  insulated.
Electrical/phone box on exterior wall
The air barrier shall be installed behind electrical or
						  communication boxes or air sealed boxes shall be installed.
HVAC register boots
HVAC supply and return register boots shall be sealed
						  to the subfloor, wall covering or ceiling penetrated by the boot.
Concealed sprinklers
When required to be sealed, concealed fire sprinklers
						  shall only be sealed in a manner that is recommended by the manufacturer.
						  Caulking or other adhesive sealants shall not be used to fill voids between
						  fire sprinkler cover plates and walls or ceilings.
IC = insulation contact.
a In addition, inspection of log
				walls shall be in accordance with the provisions of ICC-400.
b Insulation installed in
				unconditioned/ventilated attic spaces is not required to be enclosed within an
				air barrier assembly.
Statutory Authority:
				  RCW
				    19.27A.020,
				  19.27A.045 and
				  chapters
				  19.27 and
				  34.05 RCW. 13-04-055, §
				  51-11R-40241, filed 2/1/13, effective
				  7/1/13.