BASC Search | Building America Solution Center

Right – Closed-cell spray foam insulation in the shared wall between the garage and living space helps to air-seal the wall and protect occupants from garage pollutants.

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When using I-joists, make sure to fill in the gaps on each side of the blocking material to air-seal the joist bay where a wall separates conditioned and unconditioned spaces.

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Side view showing air-sealing and rigid foam insulation is installed over existing wall and ceiling under a room above, then covered with new gypsum board.

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Rigid insulation and air-sealing can be used to thermally isolate garages from multifamily row houses/town houses with basement foundations in IECC Climate Zones 3 or higher.

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Side view showing how the existing garage wall and ceiling are air-sealed prior to installing rigid foam insulation on the garage side of the shared wall of an existing home.

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Wrong – Cars should never be left running in a closed garage. Air seal walls, install a garage fan, and inform home owners of the dangers of running a vehicle with the garage door shut

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Plan view (from above) showing how the existing garage wall gypsum board is cut away to air-seal the shared wall before adding rigid foam insulation on the garage and exterior walls of the home.

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No Ducts or Air Handlers Located in Garage

Guide

Guide describing how to design HVAC systems to be located within the conditioned space of the home, either in a utility closet or in an attic, basement, or crawl space.

Air Leakage Testing Garage to House Air Barrier

Guide

Guide describing how to properly test the air barrier between the garage and house, and how to ensure the air barrier is tight enough to prevent garage air from entering the home.

Foam holes in open-web floor trusses to completely seal the rim joist

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Right – Every seam and nail hole in these garage-to-house walls is sealed with tape.

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Wrong: The door and filter were removed, allowing unfiltered air to enter the air handler leading to premature failure of the system due to dirt accumulation.

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Wrong - The band joist above this garage-house shared wall is not properly sealed.

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This bottom seal on this garage door looks fairly tight, except in the right corner where there is 4-inch gap.

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High Performance Building Details - Garage Band Joist Air Barrier

Reference

Information sheet about air barriers.

Gaps between garage and conditioned space are properly sealed by carefully cutting and then caulking wood sections to fit between trusses above shared walls.

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The I-joist is continuous along the shared wall and serves as a natural air barrier between the garage and the house

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Air barrier at garage band joist - 1 1/2 inch rigid insulation with 2x4 sleepers

CAD File

Air barrier at garage band joist - 1 inch rigid insulation with 1x3 wood furring

CAD File

Air barrier at garage band joist - 1 inch rigid insulation with 2x2 wood furring

CAD File

Wrong - When ceiling joists over a garage run perpendicular to the adjoining wall, the joist bays must be blocked and sealed to prevent garage fumes from entering the living space

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Wrong - The faced batt insulation does not provide an air barrier in the joist bay between the garage and the conditioned space of the home.

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Wrong – An opportunity to use structural members as a natural air barrier was missed in this home and blocking was not initially planned for between the garage and living space.

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An investigation of this garage door weatherstripping shows that the installed seal wasn’t long enough to extend across the entire length of the door and it appears that rodents chewed into the weatherstripping on the right to make the hole even larger.

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Garage IAQ – Standard + Best Practice Examples

Video

Video describing examples of poor air sealing in a new home and good air sealing of the garage-to-house air barrier in a gut rehab.

Garage Rim/Band Joist Adjoining Conditioned Space

Guide

Guide describing the air-sealing of rim joists on walls connecting homes and attached garages.

Floor Above Garage

Video

Video describing best practices for air-sealing floors above garages.

Garage Rim/Band Joist Adjoining Conditioned Space

Video

Video describing best practices for air sealing an attached garage during construction using plywood and spray foam in the band joist and providing an exhaust fan to ventilate and depressurize the attic.

Rigid Foam Insulation Installed Between Existing House and Garage Walls

Guide

Guide describing how to upgrade walls that separate the garage from the house by providing a continuous air control layer on the garage side of the wall and adding rigid foam insulation.

Floor Above Garage

Guide

Guide describing how to create an air barrier between the garage and the conditioned space above it to prohibit pollutants from entering a home's interior.