4.1005.3 Accessible Floors—Batt Insulation Over Existing Insulation

Attic Floors
For supporting material, see Building America Solution Center.
Desired Outcome: 
Insulation controls heat transfer through ceiling

Existing insulation will be in contact with 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 prior to installing additional insulation on top

Ensure proper performance of insulation


If the top of the existing insulation is below the top of the framing, new batts will be installed parallel with framing members

If the top of the existing insulation is above the top of the framing, new batts will be installed perpendicular to framing members

Ensure uniform depth of insulation in continuous contact with existing insulation

Eliminate voids and gaps


Batts will be installed in accordance with manufacturer specifications without gaps, voids, compressions, misalignments, or wind intrusions

Insulation will be installed to prescribed R-value

Insulate to prescribed R-value   


Insulation will not be allowed on top of non- IC IC Insulation contact rated can light Can light A light fixture (or can) that is recessed into the ceiling boxes or between a heat generating appliance and a dam, unless material is rated for contact with heat generating sources

Prevent a fire hazard

Onsite documentation

A dated receipt signed by the installer will be provided that includes:

  • Coverage area
  • Thickness
  • R-value 

Document job completion to contract specifications

Confirm amount of insulation installed

Ensure ability to match bags required for total area completed

Comply with 16 CFR 460.17