3.1001.6 Firewall in Unconditioned Attic

Topic: 
Attics
Subtopic: 
Penetrations and Chases
Desired Outcome: 
Firewall separations in unconditioned attics sealed to prevent air leakage, moisture movement, and spread of fire between the unconditioned attic and conditioned space
For supporting material, see Referenced Standards.
TitleSpecification(s)Objective(s)
3.1001.6a
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

Air sealing locations will be identified between the firewall and the attic floor

Ensure a continuous air- and fire-resistance barrier will be appropriately located between conditioned and unconditioned space

3.1001.6b
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 permanent and supports appropriate load (e.g., wind, snow, insulation)

Ensure sealant does not fall out

Ensure integrity of the existing water control system

3.1001.6c
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

3.1001.6d
Joint seal

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

  • The intersection between firewall and attic floor
  • If firewall assembly is not monolithic (e.g., balloon framing, CMU, open chase, attic bypass, or with similar penetration through the attic floor plane), attic floor plane penetrations within the firewall assembly will be accessed through the firewall, fully sealed, and firewall surface restored to prevent current or future breaches of the firewall below the attic floor plane from establishing an air flow path to the attic space

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