3.1802.2 Exterior Overhangs Communicating to or Through Pressure Boundary

Topic: 
Roofs
Subtopic: 
Roof/Wall Connections
Desired Outcome: 
Rigid, airtight continuous 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 at overhang/wall interface
For supporting material, see Referenced Standards and Building America Solution Center.
TitleSpecification(s)Objective(s)
3.1802.2a
Worker safety

All worker safety specifications will be in accordance with SWS 2.0100.3 Worker Safety

Ensure worker safety, especially in regard to fall protection considerations and contaminants found in demolition, such as asbestos, lead, polychlorinated biphenyls, etc.

3.1802.2b
Occupant safety

Occupant will be notified of changes or repairs to be made

An occupant safety plan will be prepared and implemented

Ensure occupant safety

3.1802.2c
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

Identify overhang locations to determine desired location of 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 , determine hole size, framing, and material requirements (including fire rating)

Provide a safe and stable work environment

Ensure a durable, continuous 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 a fire assembly, where appropriate

3.1802.2d
Site

Items and property below and adjacent to work area will be removed from the work areas or will be adequately protected

Prevent damage to objects near the work and workers

3.1802.2e
Backing and infill

Where gaps, cracks, or holes are larger than 1/4" across and/or where the air sealing materials will be subject to temperature variations in excess of 50° F, the need for backing or infill will be evaluated

If used, backing or infill will meet specific characteristics of the fire-resistance-rated assembly, and be compatible with the characteristics of the gap, crack, or hole, including preservation of any expansion/contraction characteristics for assembly (e.g., expansion joints, steam pipes, or dissimilar material interfaces with differing coefficients of expansion)

Backing or infill will be selected that maintains sealant placement and durability while allowing for the expected movement from expansion, contraction, load deflection, settling at the location, or if existing water control measures are compromised (e.g., rain screen, drip edge, weep holes, gutter and roof drains, scuppers, or other exterior water management elements)

Minimize gap or hole size to ensure successful use of sealant

Ensure closure is durable, pest resistant, weather appropriate, and supports appropriate load (e.g., wind, snow, insulation)

Ensure sealant does not fall out

Ensure integrity of the existing water control system

3.1802.2f
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 compound ( 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

3.1802.2g
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

At the overhang, a continuous 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 created to align with the wall 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

The opening will be closed off with a rigid material Rigid material Drywall, oriented strand board, duct board, cardboard, or any other stiff product that may support the load of insulation while serving as a durable air barrier that meets assembly fire rating

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 fastened to framing as appropriate

Rigid material Rigid material Drywall, oriented strand board, duct board, cardboard, or any other stiff product that may support the load of insulation while serving as a durable air barrier and all openings will be sealed to form a complete 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

Prevent air leakage by creating a durable 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 continuous with the wall 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

Ensure material is able to support wind and insulation loads

Ensure final gap is sealed with appropriate sealant

3.1802.2h
Quality assurance

Overhang will be visually inspected and tested for airtightness in accordance with ASTM ASTM ASTM International, www.astm.org E 1186-03

Water management systems will be verified as maintained

Prevent air leakage through assembly

Prevent water intrusion

3.1802.2i
Ignition barrier Ignition barrier Any layer of material that protects another from catching fire due to heat or spark /fire proofing

Where rigid foam plastics are used, in no case will the final thickness exceed the manufacturer's tested thickness used to determine the maximum 75 flame spread and 450 smoke-developed index when tested to ASTM ASTM ASTM International, www.astm.org E84 or UL UL Underwriters Laboratories 723

Foam, where permissible, will be provided with ignition and thermal barriers as required by code

Other fire stop materials may be required for fire resistance-rated walls with openings required to be protected

Comply with local codes and ordinances