3.1003.6 Dropped Soffits

Topic: 
Attics
Subtopic: 
Dropped Ceilings and Soffits
Desired Outcome: 
Dropped soffits sealed to prevent air leakage and moisture movement between the attic and conditioned space
TitleSpecification(s)Objective(s)
3.1003.6a
Pre-inspection

An inspection will be conducted for mold, water leaks, and water damage before sealing a dropped ceiling or soffit

Repairs will be completed before work begins

Repair moisture-related issues
3.1003.6b
Soffit general

Air flow will be blocked at soffit in locations where access allows

Provide 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 across soffit openings
3.1003.6c
Option 1: bring soffit inside (seal at top)

Entire opening will be spanned with 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 in line with the ceiling level

Material will be cut to fit and fastened as required

Prevent air leakage from wall to attic

Reduce opening to what can be sealed with sealant

Ensure closure is permanent and supports any load (e.g., wind, insulation)

Bring soffit into thermal boundary Thermal boundary The separation between the interior and exterior environments of a building that slows heat flow

3.1003.6d
Option 2: leave soffit outside (seal at bottom or side)

Each stud bay will be spanned with 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 will be cut to fit and fastened as required

OR

Backing at each stud bay will be provided and will be sealed

OR

Side of stud bays will be sealed with 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 from bottom of soffit to top-plate

OR

A sealed rigid barrier will be installed at all transitions

Prevent air leakage from wall to soffit

Reduce opening to what can be sealed with sealant

Ensure soffit is outside of the thermal boundary Thermal boundary The separation between the interior and exterior environments of a building that slows heat flow

3.1003.6e
Soffits containing non- IC IC Insulation contact rated recessed lights

Insulation will be kept at least 3" away from the top and side of any fixtures

If dropped soffit is to be filled with insulation, then a sealed rigid barrier enclosure will be installed to maintain a 3" clearance around the entire fixture

Top of rigid barrier enclosure will be sealed with non-insulating 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 (e.g., gypsum or equivalent perm rating Perm rating The measurement of a material's ability to allow the transfer of water vapor through the material and R-value)

Prevent light fixture from overheating

Bring light fixture inside 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