Chapter 14 Exterior Walls

About this chapter: Chapter 14 addresses requirements for exterior walls of buildings. Minimum standards for wall covering materials, such as material performance and fire resistance, installation of wall coverings and the ability of the wall to provide weather protection are provided. This chapter also contains limitations on the areas and heights of combustible wall coverings based on fire separation distances, radiant heat exposure and surface burning characteristics.

Code development reminder: Code change proposals to sections preceded by the designation [BS] will be considered by the IBC—Structural Code Development Committee during the 2022 (Group B) Code Development Cycle.

Section 1401 General

1401.1 Scope

The provisions of this chapter shall establish the minimum requirements for exterior walls ; exterior wall coverings ; exterior wall openings; exterior windows and doors; and architectural trim.

Section 1402 Performance Requirements

1402.1 General

The provisions of this section shall apply to exterior walls , wall coverings and components thereof.

1402.2 Weather Protection

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. Protection against condensation in the exterior wall assembly shall be provided in accordance with Section 1404.3.

Exceptions:
  1. A weather-resistant exterior wall envelope shall not be required over concrete or masonrywalls designed in accordance with Chapters 19 and 21, respectively.
  2. Compliance with the requirements for a means of drainage, and the requirements of Sections 1403.2 and 1404.4, shall not be required for an exterior wall envelope that has been demonstrated through testing to resist wind-driven rain, including joints, penetrations and intersections with dissimilar materials, in accordance with ASTM E331 under the following conditions:

The exterior wall envelope design shall be considered to resist wind-driven rain where the results of testing indicate that water did not penetrate control joints in the exterior wall envelope , joints at the perimeter of openings or intersections of terminations with dissimilar materials.

  1. Exterior wall envelope test assemblies shall include not fewer than one opening, one control joint, one wall/eave interface and one wall sill. Tested openings and penetrations shall be representative of the intended end-use configuration.
  2. Exterior wall envelope test assemblies shall be not less than 4 feet by 8 feet (1219 mm by 2438 mm) in size.
  3. Exterior wall envelope assemblies shall be tested at a minimum differential pressure of 6.24 pounds per square foot (0.297 kN/m 2 ).
  4. Exterior wall envelope assemblies shall be subjected to a minimum test exposure duration of 2 hours.

[BS] 1402.3 Structural

Exterior walls , and the associated openings, shall be designed and constructed to resist safely the superimposed loads required by Chapter 16.

1402.4 Fire Resistance

Exterior walls shall be fire-resistance rated as required by other sections of this code with opening protection as required by Chapter 7.

1402.5 Water-Resistive Barriers

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. Combustibility shall be determined in accordance with Section 703.3. 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 .

Exceptions:
  1. Walls in which the water-resistive barrier is the only combustible component and the exterior wall has a wall covering of brick, concrete, stone, terra cotta, stucco or steel with minimum thicknesses in accordance with Table 1404.2.
  2. Walls in which the water-resistive barrier is the only combustible component and the water-resistive barrier complies with the following:
    1. A peak heat release rate of less than 150 kW/m 2 , a total heat release of less than 20 MJ/m 2 and an effective heat of combustion of less than 18 MJ/kg when tested on specimens at the thickness intended for use, in accordance with ASTM E1354, in the horizontal orientation and at an incident radiant heat flux of 50 kW/m 2 .
    2. A flame spread index of 25 or less and a smoke-developed index of 450 or less as determined in accordance with ASTM E84 or UL 723, with test specimen preparation and mounting in accordance with ASTM E2404.

    [BS] 1402.6 Flood Resistance

    For buildings in flood hazard areas as established in Section 1612.3, exterior walls extending below the elevation required by Section 1612 shall be constructed with flood-damage-resistant materials.

    [BS] 1402.7 Flood Resistance for Coastal High-Hazard Areas and Coastal A Zones

    For buildings in coastal high-hazard areas and coastal A zones as established in Section 1612.3, electrical, mechanical and plumbing system components shall not be mounted on or penetrate through exterior walls that are designed to break away under flood loads .

    Section 1403 Materials

    1403.1 General

    Materials used for the construction of exterior walls shall comply with the provisions of this section. Materials not prescribed herein shall be permitted, provided that any such alternative has been approved .

    1403.2 Water-Resistive Barrier

    Not fewer than one layer of water-resistive barrier material shall be attached to the studs or sheathing, with flashing as described in Section 1404.4, in such a manner as to provide a continuous water-resistive barrier behind the exterior wall veneer . Water-resistive barriers shall comply with one of the following:

    1. No. 15 felt complying with ASTM D226, Type 1.
    2. ASTM E2556, Type I or II.
    3. ASTM E331 in accordance with Section 1402.2.
    4. Other approved materials installed in accordance with the manufacturer's installation instructions.

    [BS] 1403.3 Wood

    Exterior walls of wood construction shall be designed and constructed in accordance with Chapter 23.

    [BS] 1403.3.1 Basic Hardboard

    Basic hardboard shall conform to the requirements of ANSI A135.4.

    [BS] 1403.3.2 Hardboard Siding

    Hardboard siding shall conform to the requirements of ANSI A135.6 and, where used structurally, shall be so identified by the label of an approved agency.

    [BS] 1403.4 Masonry

    Exterior walls of masonry construction shall be designed and constructed in accordance with this section and Chapter 21. Masonry units , mortar and metal accessories used in anchored and adhered veneer shall meet the physical requirements of Chapter 21. The backing of anchored and adhered veneer shall be of concrete, masonry, steel framing or wood framing. Continuous insulation meeting the applicable requirements of this code shall be permitted between the backing and the masonry veneer .

    [BS] 1403.5 Metal

    Exterior walls constructed of cold-formed or structural steel shall be designed in accordance with Chapter 22. Exterior walls constructed of aluminum shall be designed in accordance with Chapter 20.

    [BS] 1403.5.1 Aluminum Siding

    Aluminum siding shall conform to the requirements of AAMA 1402.

    [BS] 1403.5.2 Cold-Rolled Copper

    Copper shall conform to the requirements of ASTM B370.

    [BS] 1403.5.3 Lead-Coated Copper

    Lead-coated copper shall conform to the requirements of ASTM B101.

    [BS] 1403.6 Concrete

    Exterior walls of concrete construction shall be designed and constructed in accordance with Chapter 19.

    [BS] 1403.7 Glass-Unit Masonry

    Exterior walls of glass-unit masonry shall be designed and constructed in accordance with Chapter 21.

    1403.8 Plastics

    Plastic panel, apron or spandrel walls as defined in this code shall not be limited in thickness, provided that such plastics and their assemblies conform to the requirements of Chapter 26 and are constructed of approved weather-resistant materials of adequate strength to resist the wind loads for cladding specified in Chapter 16.

    1403.9 Vinyl Siding

    Vinyl siding shall be certified and labeled as conforming to the requirements of ASTM D3679 by an approved quality control agency.

    1403.10 Fiber-Cement Siding

    Fiber-cement siding shall conform to the requirements of ASTM C1186, Type A (or ISO 8336, Category A), and shall be so identified on labeling listing an approved quality control agency.

    1403.11 Exterior Insulation and Finish Systems

    1403.12 Polypropylene Siding

    Polypropylene siding shall be certified and labeled as conforming to the requirements of ASTM D7254 and those of Section 1403.12.1 or 1403.12.2 by an approved quality control agency. Polypropylene siding shall be installed in accordance with the requirements of Section 1404.18 and in accordance with the manufacturer's instructions. Polypropylene siding shall be secured to the building so as to provide weather protection for the exterior walls of the building.

    1403.12.1 Flame Spread Index

    The certification of the flame spread index shall be accompanied by a test report stating that all portions of the test specimen ahead of the flame front remained in position during the test in accordance with ASTM E84 or UL 723.

    1403.12.2 Fire Separation Distance

    The fire separation distance between a building with polypropylene siding and the adjacent building shall be not less than 10 feet (3048 mm).

    1403.13 Foam Plastic Insulation

    Foam plastic insulation used in exterior wall covering assemblies shall comply with Chapter 26.

    1403.14 Attachments Through Insulation

    Exterior wall coverings attached to the building structure through foam plastic insulating sheathing shall comply with the attachment requirements of Section 2603.11, 2603.12, or 2603.13.

    Section 1404 Installation of Wall Coverings

    1404.1 General

    Exterior wall coverings shall be designed and constructed in accordance with the applicable provisions of this section.

    1404.2 Weather Protection

    Exterior walls shall provide weather protection for the building. The materials of the minimum nominal thickness specified in Table 1404.2 shall be acceptable as approved weather coverings.

    MINIMUM THICKNESS OF WEATHER COVERINGS Stone (natural) Architectural cast stone Three-coat work over: Metal plaster base Cast-in-place or precast concrete Two-coat work over: Cast-in-place or precast concrete Terra cotta (anchored) For SI: 1 inch = 25.4 mm, 1 ounce = 28.35 g, 1 square foot = 0.093 m 2 .
    1. Wood siding of thicknesses less than 0.5 inch shall be placed over sheathing that conforms to Section 2304.6.
    2. Exclusive of texture.
    3. As measured at the bottom of decorative grooves.
    4. 16 ounces per square foot for cold-rolled copper and lead-coated copper, 12 ounces per square foot for copper shingles, high-yield copper and lead-coated high-yield copper.

    1404.3 Vapor Retarders

    Vapor retarder materials shall be classified in accordance with Table 1404.3(1). A vapor retarder shall be provided on the interior side of frame walls in accordance with Tables 1404.3(2) and 1404.3(3), or an approved design using accepted engineering practice for hygrothermal analysis. The appropriate climate zone shall be selected in accordance with Chapter 3 of the International Energy Conservation Code.

    Where a Class II vapor retarder is used in combination with foam plastic insulating sheathing installed as continuous insulation on the exterior side of frame walls, the continuous insulation shall comply with Table 1404.3(4) and the Class II vapor retarder shall have a vapor permeance greater than 1 perm when measured by ASTM E96 water method (Procedure B). Use of a Class I interior vapor retarder in frame walls with a Class I vapor retarder on the exterior side shall require an approved design.

    Exceptions:
    1. Basementwalls.
    2. Below-grade portion of any wall.
    3. Construction where accumulation, condensation or freezing of moisture will not damage the materials.
    4. Class I and II vapor retarders with vapor permeance greater than 1 perm when measured by ASTM E96 water method (Procedure B) shall be allowed on the interior side of any frame wall in all climate zones.
    VAPOR RETARDER MATERIALS AND CLASSES
    VAPOR RETARDER CLASS ACCEPTABLE MATERIALS
    I Sheet polyethylene, nonperforated aluminum foil, or other approved materials with a perm rating of less than or equal to 0.1
    II Kraft-faced fiberglass batts or vapor retarder paint or other approved materials, applied in accordance with the manufacturer's instructions for a perm rating greater than 0.1 and less than or equal to 1.0
    III Latex paint, enamel paint, or other approved materials, applied in accordance with the manufacturer's instructions for a perm rating of greater than 1.0 and less than or equal to 10
    TABLE 1404.3(2) VAPOR RETARDER OPTIONS
    1. See also Sections 1404.3.1 and 1404.3.2.
    TABLE 1404.3(3) CLASS III VAPOR RETARDERS Continuous insulation with R -value ≥ R-10 over 2 × 4 wall Continuous insulation with R -value ≥ R-15 over 2 × 6 wall
    1. Vented cladding shall include vinyl lap siding, polypropylene, or horizontal aluminum siding, brickveneer with airspace as specified in this code, and other approved vented claddings.
    2. The requirements in this table apply only to insulation used to control moisture in order to permit the use of Class III vapor retarders. The insulation materials used to satisfy this option also contribute to but do not supersede the thermal envelope requirements of the International Energy Conservation Code.
    CONTINUOUS INSULATION WITH CLASS II VAPOR RETARDER
    CLIMATE ZONE PERMITTED CONDITIONS a
    3 Continuous insulation with R -value ≥ R-2
    4, 5, 6 Continuous insulation with R -value ≥ R-3 over 2 × 4 wall
    Continuous insulation with R -value ≥ R-5 over 2 × 6 wall
    7 Continuous insulation with R -value ≥ R-5 over 2 × 4 wall
    Continuous insulation with R -value ≥ R-7.5 over 2 × 6 wall
    8 Continuous insulation with R -value ≥ R-7.5 over 2 × 4 wall
    Continuous insulation with R -value ≥ R-10 over 2 × 6 wall
    1. In addition to the vapor retarder, spray foam with a maximum permeance 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 comply with the continuous insulation requirement only for the moisture control purposes of this table where the spray foam R -value plus any continuous insulation R -value provided equals or exceeds the specified continuous insulation R -value.

    1404.3.1 Spray Foam Plastic Insulation for Moisture Control With Class III Vapor Retarders

    For purposes of compliance with Table 1404.3(3), spray foam with a maximum permeance of 1.5 perms at the installed thickness applied to the interior cavity side of wood structural panels , fiberboard , insulating sheathing or gypsum shall be deemed to meet the continuous insulation moisture control requirement where the spray foam R -value meets or exceeds the specified continuous insulation R -value.

    1404.3.2 Hybrid Insulation for Moisture Control With Class III Vapor Retarders

    For the purposes of compliance with Table 1404.3(3), the combined R -values of spray foam plastic insulation and continuous insulation shall be permitted to be counted toward the continuous R -value requirement.

    1404.4 Flashing

    Flashing shall be installed in such a manner so as to prevent moisture from entering the wall or to redirect that moisture to the surface of the exterior wall finish or to a water-resistive barrier complying with Section 1403.2 and that is part of a means of drainage complying with Section 1402.2. Flashing shall be installed at the perimeters of exterior door and window assemblies, penetrations and terminations of exterior wall assemblies, exterior wall intersections with roofs, chimneys, porches, decks, balconies and similar projections and at built-in gutters and similar locations where moisture could enter the wall. Flashing with projecting flanges shall be installed on both sides and the ends of copings, under sills and continuously above projecting trim. Where self-adhered membranes are used as flashings of fenestration in wall assemblies, those self-adhered flashings shall comply with AAMA 711. Where fluid applied membranes are used as flashing for exterior wall openings, those fluid applied membrane flashings shall comply with AAMA 714.

    1404.4.1 Exterior Wall Pockets

    In exterior walls of buildings or structures, wall pockets or crevices in which moisture can accumulate shall be avoided or protected with caps or drips, or other approved means shall be provided to prevent water damage.

    1404.4.2 Masonry

    Flashing and weep holes in anchored veneer designed in accordance with Section 1404.6 shall be located not more than 10 inches (245 mm) above finished ground level above the foundation wall or slab. At other points of support including structural floors, shelf angles and lintels, flashing and weep holes shall be located in the first course of masonry above the support.

    1404.5 Wood Veneers

    Wood veneers on exterior walls of buildings of Types I, II, III and IV construction shall be not less than 1 inch (25 mm) nominal thickness, 0.438-inch (11.1 mm) exterior hardboard siding or 0.375-inch (9.5 mm) exterior-type wood structural panels or particleboard and shall conform to the following:

    1. The veneer shall not exceed 40 feet (12 190 mm) in height above grade. Where fire-retardant-treated wood is used, the height shall not exceed 60 feet (18 290 mm) in height above grade.
    2. The veneer is attached to or furred from a noncombustible backing that is fire-resistance rated as required by other provisions of this code.
    3. Where open or spaced wood veneers (without concealed spaces) are used, they shall not project more than 24 inches (610 mm) from the building wall.

    [BS] 1404.6 Anchored Masonry Veneer

    Anchored masonry veneer shall comply with the provisions of Sections 1404.6 through 1404.9 and Sections 12.1 and 12.2 of TMS 402.

    [BS] 1404.6.1 Tolerances

    Anchored masonry veneers in accordance with Chapter 14 are not required to meet the tolerances in Article 3.3 F1 of TMS 602.

    [BS] 1404.6.2 Seismic Requirements

    Anchored masonry veneer located in Seismic Design Category C, D, E or F shall conform to the requirements of Section 12.2.2.11 of TMS 402.

    [BS] 1404.7 Stone Veneer

    Anchored stone veneer units not exceeding 10 inches (254 mm) in thickness shall be anchored directly to masonry, concrete or to stud construction by one of the following methods:

    1. With concrete or masonrybacking, anchor ties shall be not less than 0.1055-inch (2.68 mm) corrosion-resistant wire, or approved equal, formed beyond the base of the backing. The legs of the loops shall be not less than 6 inches (152 mm) in length bent at right angles and laid in the mortarjoint, and spaced so that the eyes or loops are 12 inches (305 mm) maximum on center in both directions. There shall be provided not less than a 0.1055-inch (2.68 mm) corrosion-resistant wire tie, or approved equal, threaded through the exposed loops for every 2 square feet (0.2 m 2 ) of stone veneer . This tie shall be a loop having legs not less than 15 inches (381 mm) in length bent so that the tie will lie in the stone veneermortarjoint. The last 2 inches (51 mm) of each wire leg shall have a right-angle bend. One-inch (25 mm) minimum thickness of cement grout shall be placed between the backing and the stone veneer .
    2. With wood stud backing, a 2-inch by 2-inch (51 by 51 mm) 0.0625-inch (1.59 mm) zinc-coated or nonmetallic coated wire mesh with two layers of water-resistive barrier in accordance with Section 1403.2 shall be applied directly to wood studs spaced not more than 16 inches (406 mm) on center. On studs, the mesh shall be attached with 2-inch-long (51 mm) corrosion-resistant steel wire furring nails at 4 inches (102 mm) on center providing a minimum 1.125-inch (29 mm) penetration into each stud and with 8d annular threaded nails at 8 inches (203 mm) on center, into top and bottom plates or with equivalent wire ties. There shall be not less than a 0.1055-inch (2.68 mm) zinc-coated or nonmetallic coated wire, or approved equal, attached to the stud with not smaller than an 8d (0.120 in. diameter) annular threaded nail for every 2 square feet (0.2 m 2 ) of stone veneer . This tie shall be a loop having legs not less than 15 inches (381 mm) in length, so bent that the tie will lie in the stone veneermortarjoint. The last 2 inches (51 mm) of each wire leg shall have a right-angle bend. One-inch (25 mm) minimum thickness of cement grout shall be placed between the backing and the stone veneer .
    3. With cold-formed steel stud backing, a 2-inch by 2-inch (51 by 51 mm) 0.0625-inch (1.59 mm) zinc-coated or nonmetallic coated wire mesh with two layers of water-resistive barrier in accordance with Section 1403.2 shall be applied directly to steel studs spaced a not more than 16 inches (406 mm) on center. The mesh shall be attached with corrosion-resistant #8 self-drilling, tapping screws at 4 inches (102 mm) on center, and at 8 inches (203 mm) on center into top and bottom tracks or with equivalent wire ties. Screws shall extend through the steel connection not fewer than three exposed threads. There shall be not less than a 0.1055-inch (2.68 mm) corrosion-resistant wire, or approved equal, attached to the stud with not smaller than a #8 self-drilling, tapping screw extending through the steel framing not fewer than three exposed threads for every 2 square feet (0.2 m 2 ) of stone veneer . This tie shall be a loop having legs not less than 15 inches (381 mm) in length, so bent that the tie will lie in the stone veneermortarjoint. The last 2 inches (51 mm) of each wire leg shall have a right-angle bend. Cement grout not less than 1 inch (25 mm) in thickness shall be placed between the backing and the stone veneer . The cold-formed steel framing members shall have a minimum bare steel thickness of 0.0428 inches (1.087 mm).

    [BS] 1404.8 Slab-Type Veneer

    Anchored slab-type veneer units not exceeding 2 inches (51 mm) in thickness shall be anchored directly to masonry, concrete or light-frame construction . For veneer units of marble, travertine, granite or other stone units of slab form, ties of corrosion-resistant dowels in drilled holes shall be located in the middle third of the edge of the units, spaced not more than 24 inches (610 mm) apart around the periphery of each unit with not less than four ties per veneer unit. Units shall not exceed 20 square feet (1.9 m 2 ) in area. If the dowels are not tight fitting, the holes shall be drilled not more than 0.063 inch (1.6 mm) larger in diameter than the dowel, with the hole countersunk to a diameter and depth equal to twice the diameter of the dowel in order to provide a tight-fitting key of cement mortar at the dowel locations where the mortar in the joint has set. Veneer ties shall be corrosion-resistant metal capable of resisting, in tension or compression, a force equal to two times the weight of the attached veneer . If made of sheet metal, veneer ties shall be not smaller in area than 0.0336 by 1 inch (0.853 by 25 mm) or, if made of wire, not smaller in diameter than 0.1483-inch (3.76 mm) wire.

    [BS] 1404.9 Terra Cotta

    Anchored terra cotta or ceramic units not less than 1 5 /8 inches (41 mm) thick shall be anchored directly to masonry, concrete or stud construction. Tied terra cotta or ceramic veneer units shall be not less than 1 5 /8 inches (41 mm) thick with projecting dovetail webs on the back surface spaced approximately 8 inches (203 mm) on center. The facing shall be tied to the backing wall with corrosion-resistant metal anchors of not less than No. 8 gage wire installed at the top of each piece in horizontal bed joints not less than 12 inches (305 mm) nor more than 18 inches (457 mm) on center; these anchors shall be secured to 1 /4-inch (6.4 mm) corrosion-resistant pencil rods that pass through the vertical aligned loop anchors in the backing wall. The veneer ties shall have sufficient strength to support the full weight of the veneer in tension. The facing shall be set with not less than a 2-inch (51 mm) space from the backing wall and the space shall be filled solidly with Portland cement grout and pea gravel. Immediately prior to setting, the backing wall and the facing shall be drenched with clean water and shall be distinctly damp when the grout is poured.

    [BS] 1404.10 Adhered Masonry Veneer

    Adhered masonry veneer shall comply with the applicable requirements in this section and Sections 12.1 and 12.3 of TMS 402.