Specification History

SWS Version Created Specification ID Title Specification Objective Rationale Status
Version TBD 10/22/2025 - 12:16 4.0102.1c Material selection

Select insulation materials that have a flame spread and smoke development index of 75/450 or less when tested in accordance with ASTM E84 or UL 723

Select fire safe insulation

 Flagged during NREL administrative review of public facing resources; it was determined best to remove the redline language essentially reverting to original language. 1. Because perm rating relates to moisture permeability, not fire resistance as the objective states and 2. Perm ratings refer to the full thickness of an installed material which is not appropriate for the SWS to specify. To alleviate confusion and to maintain the guiding principles of the SWS, the proposed redline change will not be accepted with the 2025 updates. Red Line
Version 2025 04/28/2025 - 16:40 4.0102.1c Material selection

Select insulation materials that do not exceed a perm rating of 2 and have a flame spread and smoke development index of 75/450 or less when tested in accordance with ASTM E84 or UL 723

Select fire safe insulation

 The research linked applies to exterior walls, not attics. In attics the thickness of the insulation is sufficient in nearly all cases to stop vapor diffusion, and additional ignition barriers will also accomplish the same thing without limiting the type of insulation to be used. If anything, require that the insulation have a certain vapor perm rating in cold climates. In the field, roof leaks are far more problematic than vapor diffusion and no contractors in our region would install closed cell on a roof deck for that reason. The R value installed should inhibit moisture diffusion and specifying closed cell foam could be problematic if a roof leak occurred. Foam 6-8 inches will meet class 2 vapor retarder requirements. Red Line
Version 2025 09/24/2023 - 17:08 4.0102.1c Material selection

Select insulation materials that do not exceed a perm rating of 2 and have a flame spread and smoke development index of 75/450 or less when tested in accordance with ASTM E84 or UL 723

Select fire safe insulation

 The research linked applies to exterior walls, not attics. In attics the thickness of the insulation is sufficient in nearly all cases to stop vapor diffusion, and additional ignition barriers will also accomplish the same thing without limiting the type of insulation to be used. If anything, require that the insulation have a certain vapor perm rating in cold climates. In the field, roof leaks are far more problematic than vapor diffusion and no contractors in our region would install closed cell on a roof deck for that reason. The R value installed should inhibit moisture diffusion and specifying closed cell foam could be problematic if a roof leak occurred. Foam 6-8 inches will meet class 2 vapor retarder requirements. Red Line
Version 2020 08/14/2020 - 14:23 4.0102.1c Material selection

Select insulation materials that have a flame spread and smoke development index of 75/450 or less when tested in accordance with ASTM E84 or UL 723

Select fire safe insulation

 Black Line
Version 2020 08/14/2020 - 14:23 4.0102.1c Material selection

Select insulation materials that have a flame spread and smoke development index of 75/450 or less when tested in accordance with ASTM E84 or UL 723

Select fire safe insulation

 Black Line
Version 2020 08/14/2020 - 14:23 4.0102.1c Material selection

Select insulation materials that have a flame spread and smoke development index of 75/450 or less when tested in accordance with ASTM E84 or UL 723

Select fire safe insulation

 Black Line