3.1005.3 Air Sealing Complex Ceiling Planes

Topic: 
Attics
Subtopic: 
Other Ceiling Materials
Desired Outcome: 
Configuration of complex ceiling planes will be simplified by spanning interior soffits, chases, direct penetrations, and other cavities to provide a continuously sealed air barrier Air barrier The separation between the interior and exterior environments of a building that slows air flow to the point that no smoke movement is visible at 50 pascals of pressure difference across the boundary between unconditioned attic and conditioned space
For supporting material, see Referenced Standards.
TitleSpecification(s)Objective(s)
3.1005.3a
Pre-inspection

Conduct pre-inspection in accordance with SWS 2.0100.4 Work Area Inspection and Stabilization

Gaps, cracks, and holes in fire separations located within the work area will be visually identified and incorporated into air sealing work scope, including those that span two conditioned or unconditioned spaces

Where drawings are available that identify specific fire-resistance ratings (i.e., 1 hour, 2 hour), materials and methods will be employed to preserve or restore such rating

Where drawings are unavailable or do not identify specific fire-resistance ratings, the fire-resistance rating of the assembly may be inferred from the current construction (i.e., single 5/8 sheetrock, concrete masonry unit), and materials and methods employed will be consistent with restoring or preserving such inferred fire-resistance rating

Repairs necessary to stabilize work areas and protect or preserve integrity of energy improvement will be completed before subject work begins

Ensure durability of repairs

3.1005.3b
Locate air sealing plane

Work area will be cleared of existing insulation to locate and identify the optimal air sealing plane

Elevation changes, including interior soffits, chases, direct penetrations, and other changes in elevation, will be identified to determine which will be placed on the conditioned side of the air barrier Air barrier The separation between the interior and exterior environments of a building that slows air flow to the point that no smoke movement is visible at 50 pascals of pressure difference across the boundary and which will be sealed at all surfaces

Where practical, the total square footage of the air barrier Air barrier The separation between the interior and exterior environments of a building that slows air flow to the point that no smoke movement is visible at 50 pascals of pressure difference across the boundary will be minimized by capping or sealing openings in the prime air-barrier plane, rather than on all sides of the elevation change

Minimize gross air barrier Air barrier The separation between the interior and exterior environments of a building that slows air flow to the point that no smoke movement is visible at 50 pascals of pressure difference across the boundary (and subsequent thermal barrier) square footage by sealing over elevation changes in unconditioned attic spaces

3.1005.3c
Spanning material selection

Materials used to span elevation changes will be rigid and self-supporting over the distance spanned

Materials will be consistent with existing or intended fire-resistance assemblies

Materials will be compatible with adjacent materials and with any proposed insulation designed to come in contact with it

The perimeters of all materials installed to span elevation changes will be sealed on all exposed edges with compatible sealants

Seals will be used that prevent visible air movement using chemical smoke at 50 pascals of pressure difference

Prevent air leakage from complex ceiling planes.  Provide airtight, durable seal that does not move, bend, or sag and can support the weight of installed insulation

3.1005.3d
Support

Support material Support material Typically, wooden strips that provide support over holes greater than 24" in size for less rigid air barrier materials will be installed for spans wider than 24" except when air-barrier material is rated to span greater distance under load (e.g., wind, insulation)

Ensure seal stays in place and does not sag

3.1005.3e
Joint seal

Continuous seal will be installed around seams, cracks, joints, edges, penetrations, and connections

Prefabricated units may be used when meeting the desired outcome

Provide airtight, durable seal that does not move, bend, or sag

3.1005.3f
Sealant selection

Sealants will be compatible with their intended surfaces and applied in accordance with manufacturer specifications

Selection will be durable, pest resistant, and have a weather-appropriate seal

Indoor sealants will be low volatile organic compounds ( VOC VOC Volatile organic compound ) products that meet independent testing and verification protocols, such as Green Seal GS-36, "GREENGUARD Children and Schools," or comparable certifications

Fire-resistance-rated assemblies will be provided with sealants permitted by the authority having jurisdiction and adopted building code

Prevent intrusion of moisture and pests into the sealed assembly

Prevent exposing workers or occupants to excessive VOC VOC Volatile organic compound levels

Ensure sealant meets or exceeds the performance characteristics of the assembly and is compliant with local fire code requirements

3.1005.3g
Adjacent framing

All remaining gaps will be sealed at the top of the ceiling

Provide airtight framing from one finished side of the ceiling to the other