Specifications

2008 Residential Appendices RA3-28
Appendix RA3 – Residential Field Verification and Diagnostic Test Protocols
cover (usually a piece of plywood) is installed at the 10 ft. level above the entry closet.
Hard covers become part of the ceiling air barrier and shall be air-tight.
Inset Stapling In windy areas installers often staple the flanges of faced batts to the sides of the stud in
order to assure that the insulation remains in place until covered with drywall, particularly
on the wall between the house and the garage where there isn't any exterior sheathing to
help keep the insulation in place. The void created by the flange inset shall not extend
more than two inches from the stud on each side.
Net Free-Area The net free-area of a vent cover is equal to the total vent opening less the interference to
air flow caused by the screen or louver. Screened or louvered vent opening covers are
typically marked by the manufacturer with the "net free-area." For example a 22.5 in. by
3.5 in. eave vent screen with a total area of 78.75 square inches may have a net free-area
of only 45 square inches.
Voids When batt insulation is pushed too far into a wall stud cavity a void is created between the
front of the batt and the drywall. Batts shall be fully lofted and fill the cavity front-to-back.
Small voids less than ¾ in. deep on the front or back of a batt shall be allowed as long as
the total void area is not over 10 percent of the batt surface area. This definition shall not
preclude the practice of inset stapling as long as the void created by the flange inset
meets the specification in the definition of inset stapling. Improper spraying or blowing of
insulation in ceilings and wall cavities can result in areas with insufficient insulation not
meeting the specified installed density and R-value. Wall and cathedral ceiling cavity
areas where cellulose insulation has fallen away shall be filled with insulation.
Depressions in netting or material supporting blown insulation in walls and cathedral
ceilings shall be filled with insulation.
RA3.5.3 Raised Floors and Floors Over Garages
•
Batts shall be correctly sized to fit snugly at the sides and ends, but not be so large as to buckle.
• Batts shall be cut to fit properly without gaps. Insulation shall not be doubled-over or compressed.
• Insulation shall be in contact with an air barrier - usually the subfloor.
• On floors that are over garages, or where there is an air space between the insulation and the
subfloor, the rim joist shall be insulated.
• Batts shall be cut to butt-fit around wiring and plumbing, or be split (delaminated) so that one layer
can fit behind the wiring or plumbing, and one layer fit in front.
• If the insulation is faced, the facing shall be placed toward the living space and be in contact with the
underside of the floor sheathing. Continuous support shall be provided to keep the facing in contact
with the floor sheathing. Filling the entire cavity with insulation and providing support with netting at
the bottom of the framing is one acceptable method.
• Insulation shall be properly supported to avoid gaps, voids, and compression.
RA3.5.4 Wall Insulation
RA3.5.4.1 Batt Installation
•
Wall stud cavities shall be caulked or foamed to provide a substantially air-tight envelope to the
outdoors, attic, garage and crawl space. Special attention shall be paid to plumbing and wiring
penetrations through the top plates, electrical boxes that penetrate the sheathing, and the sheathing
seal to the bottom plate. All gaps in the air barrier greater then 1/8 inch shall be caulked, or sealed
with expansive or minimally expansive foam.
• Installation shall uniformly fill the cavity side-to-side, top-to-bottom, and front-to-back.