Special Notes and Alternate Allowances:
Mineral Wool Allowance- NFPA 285 tables for mineral wool are not available. For any listed insulation, mineral wool may be used as a replacement for combustible insulation.
No Insulation Allowance - NFPA 285 tables for no insulation are not available. Where the WRB is allowed over combustible insulation, those WRB’s allowed over the insulation may be used on the base-wall with no insulation.
- It is not permitted to remove insulation from a table – unless the table allows WRB over the insulation. In this case, when the insulation is removed, then that WRB over the insulation is to be used on the base wall surface.
- Do not use the WRB as listed on the base wall surface when removing the insulation to allow the WRB over the insulation.
- Adhere to the maximum air gap as stated within the approval when performing this process.
WRB Allowance - GCP PERM-A-BARRIER® or PERM-A-BARRIER® Ultra may replace any WRB shown since this WRB is less combustible than the WRBs listed in the approvals.
WRBs may not be used under and over insulation. -Where an approval does not list “None” for WRB, None may be used to comply with the point above.
Where an approval does not list air gaps for specific claddings, use the air gap tested for brick (usually 2 inches) as a maximum.
Walls containing up to 3 in. Kingspan GreenGuard® XPS Insulation
Please refer to XPS manufacturers’ recommendations for window and door header details.
Walls containing XPS insulation
| Wall Components | Materials | |
| Base Wall System Use any of these options | 1 | Concrete Wall |
| 2 | Concrete Masonry Wall | |
| 3 | 20-gauge (min) 3 5/8 in. depth (min.) steel studs spaced at a maximum of 16 in. o.c. with lateral bracing every 4 ft. vertically | |
| a | 1 layer - 5/8 in. thick Type X or 1/2 in. thick Type X gypsum wallboard on interior | |
| Floorline Firestopping | 1 | 4 lb/cu ft mineral wool (i.e., Thermafiber®) in each stud cavity at each floor line, attached with Z-clips or equivalent |
| Cavity Insulation Use any of these options | 1 | None |
| 2 | Any noncombustible insulation per ASTM E136 | |
| 3 | Fiberglass (Batt type Class A ASTM E84 faced or unfaced | |
| Exterior Sheathing Use any of these options | 1 | None |
| 2 | Minimum 1/2 in. thick, exterior type gypsum sheathing | |
| 3 | Minimum 5/8 in. thick, Type X, exterior type gypsum sheathing | |
| Air Barrier or Weather-Resistive Barrier Applied to Exterior Sheathing | 1 | PERM-A-BARRIER® Aluminum Wall Membrane |
| 2 | PERM-A-BARRIER® VPL | |
| 3 | PERM-A-BARRIER® VPS | |
| 4 | PERM-A-BARRIER® NPL | |
| 5 | PERM-A-BARRIER® Ultra | |
| Note | All WRB to be installed at the indicated or recommended application rates and per the manufacturer installation instructions | |
| Exterior Insulation | 1 | Kingspan GreenGuard® XPS - 1/2 in. minimum and 3 in. maximum |
| Note | Seal all insulation joints with maximum 4 in. wide asphalt or Butyl based flashing tape | |
| Exterior Veneer Use any of these options | 1 | Brick |
| a | Standard nominal 4 in. thick, clay brick | |
| b | Brick veneer anchors - standard types - installed maximum 24 in. o.c. vertically on each stud | |
| c | Maximum 2 in. air gap between exterior insulation and brick | |
| 2 | Concrete | |
| a | Minimum 2 in. thick | |
| b | Maximum 2 in. air gap between exterior insulation and concrete. | |
| 3 | CMU - Concrete Masonry Units | |
| a | Minimum 4 in. thick | |
| b | Maximum 2 in. air gap between exterior insulation and CMU | |
| 4 | Stone Veneer | |
| a | Minimum 2 in. thick limestone or natural stone veneer | |
| b | Minimum 1 1/2 in. thick cast artificial stone veneer | |
| c | Any standard non-open joint technique may be used (such as shiplap, etc.) | |
| 5 | Terracotta Cladding | |
| a | Minimum 1 1/4 in. thick | |
| b | Any standard joint installation technique may be used (such as shiplap, etc.) | |
| 6 | Portland cement-sand plaster (Stucco) over metal lath | |
| a | Minimum 3/4 in. thick | |
| b | 2 or 3-coat application | |
| c | No air gap between Stucco veneer and exterior insulation | |
Walls containing up to 4 in. Kingspan GreenGuard® XPS Insulation
Please refer to XPS manufacturers’ recommendations for window and door header details.
| Wall Components | Materials | |
| Base Wall System | 1 | 18-gauge 3 5/8 in. depth (min.) galvanized steel studs spaced at a maximum 24 in. o.c. |
| a | 1 layer - 5/8 in. thick gypsum wallboard on interior | |
| Cavity Insulation | 1 | Unfaced fiberglass batt insulation |
| Exterior Sheathing | 1 | One (1) layer 1/2 in. thick exterior type gypsum |
| Air Barrier or Weather-Resistive Barrier Applied to Exterior Sheathing Use any of these options | 1 | PERM-A-BARRIER® Aluminum Wall Membrane |
| 2 | PERM-A-BARRIER® VPL | |
| 3 | PERM-A-BARRIER® VPL LT | |
| 4 | PERM-A-BARRIER® VPS | |
| 5 | PERM-A-BARRIER® Ultra | |
| Exterior Insulation | 1 | Kingspan GreenGuard® XPS Insulation Board- 4 in. thickness |
| WRB Over Exterior Insulation | 1 | 10mm Keene Building Products Driwall™ Rainscreen drainage mat |
| Exterior Veneer | 1 | Glen-Gery Thin Veneer Brick |
| a | First a layer of 1/2 in. thick PermaBASE® cement board | |
| b | Laticrete MVIS™ Thin Brick Mortar applied to full surface of PermaBASE® | |
| c | Thin Veneer Brick applied with Glen-Gery Mortar Blend Portland cement-line mortar as grout | |
Walls containing Dow Styrofoam™ XPS Insulation
Please refer to XPS manufacturers’ recommendations for window and door header details.
| Wall Component | Materials | |
| Base Wall System Use either 1, 2, 3, or 4 | 1 | Concrete Wall |
| 2 | Concrete Masonry Unit (CMU) Wall | |
| 3 | Steel studs: minimum 3 5/8 in. depth, minimum 20-gauge at a maximum spacing of 24 in. OC. One layer of 5/8 in. thick Type X gypsum wallboard on interior face of studs. Gypsum wallboard joints shall receive at a minimum a LeveI 2 finish with all fasteners covered with joint compound. | |
| 4 | Wood studs: Minimum 2-inch x 4-inch FRTW wood studs spaced at a maximum of 24-inch OC. One layer of 5/8 in. thick Type X gypsum wallboard installed on interior face of wood studs. One layer of 5/8 in. thick Type X exterior gypsum sheathing installed on exterior face of wood studs. Minimum two top plates at floorlines. As an option, any thickness of plywood or OSB may be installed on exterior face of wood studs under exterior gypsum sheathing. | |
| Floorline Firestopping Required in curtain-wall construction | 4 lb/cu ft mineral wool friction fit in each stud cavity, at each floorline | |
| Stud Cavity Insulation Use either 1, 2, 3, or 4 | 1 | None |
| 2 | Fiberglass batt insulation (faced or unfaced) | |
| 3 | Mineral wool blown-in or batt insulation (faced or unfaced) | |
| 4 | Any noncombustible material | |
| Exterior Sheathing Use either 1, 2, 3, or 4 | 1 | 5/8 in. thick Type X glass mat gypsum sheathing |
| 2 | 1/2 in. thick glass mat gypsum sheathing | |
| 3 | 5/8 in. thick DensElement® sheathing - The joints of the DensElement® sheathing may be sealed with R-Guard FastFlash Liquid Flashing or approved equivalent | |
| Note | Exterior sheathing is optional for Base wall systems 1 and 2 above | |
| WRB Materials Applied to Exterior Sheathing Use either 1, 2, 3, 4, or 5 | 1 | PERM-A-BARRIER® Aluminum Wall Membrane |
| 2 | PERM-A-BARRIER® VPL | |
| 3 | PERM-A-BARRIER® VPL LT | |
| 4 | PERM-A-BARRIER® VPS | |
| 5 | PERM-A-BARRIER® Ultra | |
| Note | Any WRB shown above can be applied over Base Wall System 1 or 2 above, where able. | |
| Continuous insulation adhesive Use either 1, 2, 3, or 4 | 1 | None |
| 2 | Sto TurboStick Adhesive | |
| 3 | Sto ExtraSeal® | |
| 4 | DuPont™ Insta Stik™ quick set polyurethane adhesive | |
| Continuous insulation | DuPont™ Styrofoam™ Type IV per ASTM C578. Total thickness to be minimum 1/2 in. to maximum 3 in. XPS products include the Blue Styrofoam™, Grey Styrofoam™ (covered in ICC-ESR 2142), and Grey Styrofoam™ brand ST-100 Series (LIMS-274901) Styrofoam™ (covered in ICC-ESR 4755). | |
| Sealing of exterior insulation Use either 1 or 2 | 1 | None |
| 2 | Seal all exterior insulation joints, and as an option, veneer tie penetrations with: | |
| a | DuPont™ LiquidArmor™ - CM Flashing and Sealant-max. 50-mil wet thickness, max. 4 in. width | |
| b | DuPont™ LiquidArmor™ - LT Flashing and Sealant-max. 35-miI wet thickness, max. 4 in. width. | |
| c | Asphalt, acrylic, or butyl-based flashing tape - max. 4 in. width | |
| d | DuPont™ Great Stuff PRO™- Use on joints that are ≤ 1/4 in. width, vertical joints must be staggered & remove significant excess from the face of the XPS | |
| Secondary WRB material Use either 1, 2, or 3 | 1 | None |
| 2 | No. 15 Grade D building paper | |
| 3 | Asphalt felt in compliance with ASTM D226 | |
| Drainage Mat Use either 1 or 2 | 1 | None |
| 2 | Sto DrainScreen® - installed over Air Barrier and water-resistive barrier membrane or over continuous insulation | |
| Exterior Veneer | Stucco - Minimum 3/4 in. thick 2 - or 3-coat stucco complying with ASTM C926 applied over 2 1/2 -lb/yd^2 galvanized steel diamond mesh lath complying with ASTM C1063/C847. As an option, adhered masonry veneer, such as: Thin brick, manufactured stone, ceramic or porcelain tile may be installed over the Stucco | |
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Last Updated: 2026-06-08
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