Exterior walls shall provide the building with a weather-resistant exterior wall envelope. The exterior wall envelope shall include flashing, as described in Section 1404.4. The exterior wall envelope shall be designed and constructed in such a manner as to prevent the accumulation of water within the wall assembly by providing a water-resistive barrier behind the exterior veneer, as described in Section 1403.2, and a means for draining water that enters the assembly to the exterior. An air space cavity is not required under the exterior cladding for an exterior wall clad with lapped or panel siding made of plywood, engineered wood, hardboard, or fiber cement. Protection against condensation in the exterior wall assembly shall be provided in accordance with Section 1404.3.
Exterior walls on buildings of Type I, II, III or IV construction that are greater than 40 feet (12 192 mm) in height above grade plane and contain a combustible water-resistive barrier shall be tested in accordance with and comply with the acceptance criteria of NFPA 285. For the purposes of this section, fenestration products, flashing of fenestration products and water-resistive-barrier flashing and accessories at other locations, including through wall flashings, shall not be considered part of the water-resistive barrier.
MINIMUM THICKNESS OF WEATHER COVERINGS
|COVERING TYPE||MINIMUM THICKNESS |
|Adhered masonry veneer|
|Architectural cast stone||0.75|
|Anchored masonry veneer|
|Architectural cast stone||1.25|
|Cold-rolled copperd||0.0216 nominal|
|Copper shinglesd||0.0162 nominal|
|Exterior plywood (with sheathing)||0.313|
|Exterior plywood (without sheathing)||See Section 2304.6|
|Fiber cement lap siding||0.25c|
|Fiber cement panel siding||0.25c|
|Glass-fiber reinforced concrete panels||0.375|
|High-yield copperd||0.0162 nominal|
|Lead-coated copperd||0.0216 nominal|
|Lead-coated high-yield copper||0.0162 nominal|
|Particleboard (with sheathing)||See Section 2304.6|
|Particleboard (without sheathing)||See Section 2304.6|
|Steel (approved corrosion resistant)||0.0149|
|Stucco or exterior cement plaster|
|Three-coat work over:|
|Metal plaster base||0.875b|
|Cast-in-place or precast concrete||0.625b|
|Two-coat work over:|
|Cast-in-place or precast concrete||0.375b|
|Terra cotta (anchored)||1|
|Terra cotta (adhered)||0.25|
|Wood siding (without sheathing)a||0.5|
For SI: 1 inch = 25.4 mm, 1 ounce = 28.35 g, 1 square foot = 0.093 m2.
Class I and II vapor retarders shall not be provided on the interior side of frame walls in Zones 1 and 2. Class I vapor retarders shall not be provided on the interior side of frame walls in Zones 3 and 4 other than Marine 4. Class I or II vapor retarders shall be provided on the interior side of frame walls in Zones 5, 6, 7, 8 and Marine 4. The appropriate zone shall be selected in accordance with Chapter 3 [CE] of the International Energy Conservation Code—Commercial Provisions.
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|
|Vented cladding over wood structural panels|
Vented cladding over wood structural panels
Vented cladding over gypsum
Vented cladding over gypsum
|7 and 8|
The vapor retarder class shall be based on the manufacturer's certified testing or a tested assembly.
The following shall be deemed to meet the class specified:
|Class I:||Sheet polyethylene, nonperforated aluminum foil with a perm rating of less than or equal to 0.1.|
|Class II:||Kraft-faced fiberglass batts or paint with a perm rating greater than 0.1 and less than or equal to 1.0.|
|Class III:||Latex or enamel paint with a perm rating of greater than 1.0 and less than or equal to 10.0.|
For the purposes of this section, vented cladding shall include the following minimum clear airspaces:
On buildings of Types I, II, III and IV construction, exterior wall coverings shall be permitted to be constructed of combustible materials, complying with the following limitations:
Where permitted by Section 1405.1.1, combustible exterior wall coverings shall be tested in accordance with NFPA 268.
For fire separation distances greater than 5 feet (1524 mm), any exterior wall covering shall be permitted that has been exposed to a reduced level of incident radiant heat flux in accordance with the NFPA 268 test method without exhibiting sustained flaming. The minimum fire separation distance required for the exterior wall covering shall be determined from Table 1405.1.1.1.2 based on the maximum tolerable level of incident radiant heat flux that does not cause sustained flaming of the exterior wall covering.
MINIMUM FIRE SEPARATION FOR COMBUSTIBLE EXTERIOR WALL COVERINGS
LEVEL INCIDENTRADIANT HEAT
LEVEL INCIDENTRADIANT HEAT
For SI: 1 foot = 304.8 mm, 1 Btu/H2 • °F = 0.0057 kW/m2 • K.
Where the combustible exterior wall covering is furred out from the exterior wall and forms a solid surface, the distance between the back of the exterior wall covering and the exterior wall shall not exceed 15/8 inches (41 mm). The concealed space thereby created shall be fireblocked in accordance with Section 718.
Where MCM systems are used on exterior walls required to have a fire-resistance rating in accordance with Section 705, evidence shall be submitted to the building official that the required fire-resistance rating is maintained.
Exception: MCM systems not containing foam plastic insulation, which are installed on the outer surface of a fire-resistance-rated exterior wall in a manner such that the attachments do not penetrate through the entire exterior wall assembly, shall not be required to comply with this section.
The maximum area of a single MCM panel and the minimum vertical and horizontal separation requirements for MCM panels shall be as provided for in Table 1406.11.3.4. The maximum percentage of exterior wall area of any story covered with MCM panels shall not exceed that indicated in Table 1406.11.3.4 or the percentage of unprotected openings permitted by Section 705.8, whichever is smaller.
Exception: In buildings provided with flame barriers complying with Section 705.8.5 and extending 30 inches (760 mm) beyond the exterior wall in the plane of the floor, a vertical separation shall not be required at the floor other than that provided by the vertical thickness of the flame barrier.
|FIRE SEPARATION |
CLASS OF MCM
|MAXIMUM PERCENTAGE COVERED WITH MCM||MAXIMUM SINGLE AREA (square feet)||MINIMUM SEPARATION |
|Less than 6||—||Not Permitted||Not Permitted||—||—|
|6 or more but less than 11||CC1||10||50||8||4|
|CC2||Not Permitted||Not Permitted||—||—|
|11 or more but less than or |
equal to 30
|More than 30||CC1||50||Not Limited||3a||0|
For SI: 1 foot = 304.8 mm, 1 square foot = 0.0929 m2.
Exception: Where the building is equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1, the fire separation distance shall be permitted to be reduced to not less than 20 feet (6096 mm).
The aggregate area of MCM panels shall not exceed 25 percent of the area of any exterior wall face of the story on which those panels are installed. The area of a single MCM panel installed above the first story above grade plane shall not exceed 16 square feet (1.5 m2) and the vertical dimension of a single MCM panel shall not exceed 4 feet (1219 mm).
Exception: Where the building is equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1, the maximum aggregate area of MCM panels shall be increased to 50 percent of the exterior wall face of the story on which those panels are installed and there shall not be a limit on the maximum dimension or area of a single MCM panel.
Flame barriers complying with Section 705.8 and extending 30 inches (762 mm) beyond the exterior wall or a vertical separation of not less than 4 feet (1219 mm) in height shall be provided to separate MCM panels located on the exterior walls at one-story intervals.
Where HPL systems are used on exterior walls required to have a fire-resistance rating in accordance with Section 705, evidence shall be submitted to the building official that the required fire-resistance rating is maintained.
Exception: HPL systems not containing foam plastic insulation, which are installed on the outer surface of a fire-resistance-rated exterior wall in a manner such that the attachments do not penetrate through the entire exterior wall assembly, shall not be required to comply with this section.
The thermal barrier specified for HPL in Section 1408.10.2 is not required where: