// CODE SNIPPET
1404.3.2 Class III Vapor Retarders
JUMP TO FULL CODE CHAPTER
Class III vapor retarders shall be permitted where any one of the conditions in Table 1404.3.2 is met. Only Class III vapor retarders shall be used on the interior side of frame walls where foam plastic insulating sheathing with a perm rating of less than 1 is applied in accordance with Table 1404.3.2 on the exterior side of the frame wall.
CLASS III VAPOR RETARDERS
| ZONE | CLASS III VAPOR RETARDERS PERMITTED FOR:a |
| Marine 4 | Vented cladding over wood structural panels Vented cladding over fiberboard Vented cladding over gypsum Continuous insulation with R-value ≥ R2.5 over 2 × 4 wall Continuous insulation with R-value ≥ R3.75 over 2 × 6 wall |
| 5 | Vented cladding over wood structural panels Vented cladding over fiberboard Vented cladding over gypsum Continuous insulation with R-value ≥ R5 over 2 × 4 wall Continuous insulation with R-value ≥ R7.5 over 2 × 6 wall |
| 6 | Vented cladding over fiberboard Vented cladding over gypsum Continuous insulation with R-value ≥ R7.5 over 2 × 4 wall Continuous insulation with R-value ≥ R11.25 over 2 × 6 wall |
| 7 and 8 | Continuous insulation with R-value ≥ R10 over 2 × 4 wall Continuous insulation with R-value ≥ R15 over 2 × 6 wall |
For SI: 1 pound per cubic foot = 16 kg/m3.
- Spray foam with a maximum permanence of 1.5 perms at the installed thickness applied to the interior cavity side of wood structural panels, fiberboard, insulating sheathing or gypsum is deemed to meet the continuous insulation requirement where the spray foam R-value meets or exceeds the specified insulating sheathing R-value.
Related Code Sections
1404.3.2 Exterior Walls, Class III Vapor Retarders
Class III vapor retarders shall be permitted where any one of the conditions in Table 1404.3.2 is met. Only Class III vapor retarders shall be used ...
Building Code 2018 of Illinois > 14 Exterior Walls > 1404 Installation of Wall Coverings > 1404.3 Vapor Retarders > 1404.3.2 Class III Vapor Retarders
(1) Special Occupancies, Class I Temperature
The temperature marking specified in 500.8(C) shall not exceed the autoignition temperature of the specific gas or vapor to be encountered ...
National Electrical Code 2017 of Illinois > 5 Special Occupancies > 500 Hazardous (Classified) Locations, Classes I, II, and III, Divisions 1 and 2 > 500.8 Equipment > (D) Temperature > (1) Class I Temperature
(B) Special Occupancies, Approval for Class and Properties
, vapor, dust, or fibers/flyings that will be present. In addition, Class I equipment shall not have any exposed surface that operates ...
National Electrical Code 2017 of Illinois > 5 Special Occupancies > 500 Hazardous (Classified) Locations, Classes I, II, and III, Divisions 1 and 2 > 500.8 Equipment > (B) Approval for Class and Properties
(A) Special Occupancies, Class I Group Classifications
). Informational Note No. 2: The explosion characteristics of air mixtures of gases or vapors vary with the specific material involved. For Class I locations ...
National Electrical Code 2017 of Illinois > 5 Special Occupancies > 500 Hazardous (Classified) Locations, Classes I, II, and III, Divisions 1 and 2 > 500.6 Material Groups > (A) Class I Group Classifications
(2) Special Occupancies, Class I, Division 2
A Class I, Division 2 location is a location: In which volatile flammable gases, flammable liquid-produced vapors, or combustible liquid-produced ...
National Electrical Code 2017 of Illinois > 5 Special Occupancies > 500 Hazardous (Classified) Locations, Classes I, II, and III, Divisions 1 and 2 > 500.5 Classifications of Locations > (B) Class I Locations > (2) Class I, Division 2