Minnesota Administrative Rules
Agency 151 - Labor and Industry Department
Chapter 1309 - INTERNATIONAL RESIDENTIAL CODE
Part 1309.0703 - SECTION R703, EXTERIOR COVERING

Universal Citation: MN Rules 1309.0703

Current through Register Vol. 49, No. 13, September 23, 2024

Subpart 1. [Repealed, 32 SR 12 32 SR 12]

Subp. 2. [Repealed, 32 SR 12 32 SR 12]

Subp. 2a. IRC section R703.2 Water-resistive barrier.

Section R703.2 is amended to read as follows:

R703.2 Water-resistive barrier. One layer of No. 15 asphalt felt, free from holes and breaks, complying with ASTM D 226 for Type 1 felt or other approved water-resistive barrier shall be applied over studs or sheathing of all exterior walls. Such felt or material shall be applied horizontally, with the upper layer lapped over the lower layer not less than 2 inches (51 mm). The water-resistive barrier shall overlap the flashings required in section R703.8 not less than 2 inches (51 mm). Where joints occur in the water-resistive barrier or flashing, the joints shall be lapped not less than 6 inches (152 mm). The felt or other approved material shall be continuous up to the underside of the rafter or truss top chord and terminated at penetrations and building appendages in a manner to meet the requirements of the exterior wall envelope as described in section R703.1.

Exception: Omission of the water-resistive barrier is permitted in the following situations:

1. In detached accessory buildings.

2. Under exterior wall finish materials as permitted in Table R703.4.

3. Under paperbacked stucco lath when the paper backing is an approved water-resistive barrier.

Subp. 3. IRC section R703.

Section R703.6 is amended to read as follows:

R703.6 Exterior plaster. Installation of these materials shall be in compliance with ASTM C 926 and ASTM C 1063 and provisions of this code.
R703.6.1 Lath. All lath and lath attachments shall be of corrosion-resistant materials. Expanded metal or woven wire lath shall be attached with 11 gage nails having a 7/16-inch (11.1 mm) head or 16 gage staples, spaced at no more than 6 inches (152 mm) or as otherwise approved. Nails or staples shall penetrate wood framing support members not less than 3/4-inch (19 mm).
R703.6.1.1 Control joints and expansion joints. Provisions for the control of expansion shall be determined by the exterior plaster application designer. ASTM C 1063 sections 7.11.4 - 7.11.4.4 do not apply.

R703.6.2 Plaster. Plastering with portland cement plaster shall be not less than three coats when applied over metal lath or wire lath and shall be not less than two coats when applied over masonry, concrete, pressure-preservative treated wood, or decay-resistant wood as specified in section R317.1 or gypsum backing. If the plaster surface is completely covered by veneer or other facing material or is completely concealed, plaster application need be only two coats, provided the total thickness is as set forth in Table R702.1(1). On wood-frame construction with an on-grade floor slab system, exterior plaster shall be applied to cover, but not extend below, lath, paper, and screed.
R703.6.2.1 Weep screeds. A minimum 0.019-inch (0.5 mm) (No. 26 galvanized sheet gage), corrosion-resistant weep screed or plastic weep screed, with a minimum vertical attachment flange of 3-1/2 inches (89 mm) shall be provided at or below the foundation plate line on exterior stud walls in accordance with ASTM C 1063. The weep screed shall be placed a minimum of 4 inches (102 mm) above the earth or 2 inches (51 mm) above paved areas and shall be of a type that will allow trapped water to drain to the exterior of the building. The weather-resistant barrier shall lap the attachment flange. The exterior lath shall cover and terminate on the attachment flange of the weep screed.

R703.6.3 Water-resistive barriers. Water-resistive barriers shall be installed as required in section R703.2 and, where applied over wood-based sheathing, shall include two layers of a water-resistive vapor-permeable barrier. Each layer shall meet both of the following requirements:
1. A water resistance of not less than that of 60-minute Grade D paper; or a minimum hydrostatic head of 23-31/32 inches (60.9 cm) when tested in accordance with hydrostatic pressure test method AATCC 127-2008; or a minimum water transudation time of 60 minutes when tested in accordance with ASTM D-779.

2. A water vapor permeance of not less than that of No. 15 felt; or a minimum permeance rating of 8.5 gr/h.ft.2 in Hg (US perm) (4.9 x 1010kg/Pa.s.m2) when tested in accordance with Procedure B of ASTM E96.

Exception: One layer of water-resistive barrier complying with R703.2 is permitted when a drainage space that allows bulk water to flow freely behind the cladding is provided.

R703.6.4 Application. Each coat shall be kept in a moist condition for at least 48 hours prior to application of the next coat.

Exception: Applications installed in accordance with ASTM C 926. The second coat is permitted to be applied as soon as the first coat has attained sufficient rigidity to receive the second coat.

R703.6.5 Curing. The finish coat for two-coat cement plaster shall not be applied sooner than seven days after application of the first coat. For three-coat cement plaster, the second coat shall not be applied sooner than 48 hours after application of the first coat, except as required in section R703.6.4. The finish coat for three-coat cement plaster shall not be applied sooner than seven days after application of the second coat.

Subp. 3a. [Repealed, 32 SR 12 32 SR 12]

Subp. 4. [Repealed, 32 SR 12 32 SR 12]

Subp. 5. [Repealed, 32 SR 12 32 SR 12]

Subp. 6. [Repealed, 32 SR 12 32 SR 12]

Subp. 7. [Repealed, 32 SR 12 32 SR 12]

Subp. 8. [Repealed, 32 SR 12 32 SR 12]

Subp. 8a. Section R703.7.4.2.

IRC Section R703.7.4.2 is amended to read as follows:

R703.7.4.2 Air space. The veneer shall be separated from the sheathing by an air space of a minimum of a nominal 1 inch (25 mm) but nor more than 4-1/2 inches (114 mm).

Exception: One layer of water-resistive barrier complying with Section R703.2 is permitted when a drainage space that allows bulk water to flow freely behind the cladding is provided.

Subp. 8b. Section R703.7.4.3.

IRC Section R703.7.4.3 is amended to read as follows:

R703.7.4.3 Mortar or grout fill. As an alternate to the air space required by Section R703.7.4.2, mortar or grout shall be permitted to fill the air space. When the 1-inch (25.4 mm) space is filled with mortar, a weather-resistant membrane or building paper as described in Section R703.2 or R703.6.3 is required over studs or sheathing. When filling the air space, it is permitted to replace the sheathing and weather-resistant membrane or asphalt-saturated felt paper with a wire mesh and approved paper or an approved paper-backed reinforcement attached directly to the studs.

R703.7.4.4 Masonry veneer on sheathed substrates. On sheathed substrates, a corrosion-resistant, self-furring expanded metal lath shall be installed over the weather-resistant membrane or building paper with appropriate fasteners as described in Section R703.6.1. Fasteners shall penetrate wood supports a minimum of one inch.

Subp. 9. IRC section R703.8.

Section R703.8 is amended to read as follows:

R703.8 Flashing. Approved corrosion-resistant flashing shall be applied shingle-fashion in such a manner as to prevent entry of water into the wall cavity or penetration of water to the building structural framing components. Self-adhered membranes used as flashing shall comply with AAMA 711. The flashing shall extend to the surface of the exterior wall finish. Approved corrosion-resistant flashing shall be installed at all of the following locations:
1. Exterior window and door openings. Flashing shall be installed at the head and sides of exterior window and door openings and shall extend to the surface of the exterior wall finish or to the water-resistive barrier for subsequent drainage. Flashing at exterior window and door openings shall be installed in accordance with at least one of the following:
(a) the fenestration manufacturers installation and flashing instructions. When flashing is not addressed in the fenestration manufacturers instructions, it shall be installed in accordance with the flashing manufacturers instructions;

(b) in accordance with the flashing design or method of a registered design professional; and

(c) in accordance with other approved methods.

2. At the intersection of chimneys or other masonry construction with frame or stucco walls, with projecting lips on both sides under stucco copings.

3. Under and at the ends of masonry, wood, or metal copings and sills.

4. Continuously above all projecting wood trim.

5. Where exterior porches, decks, or stairs attach to a wall or floor assembly of wood-frame construction.

6. At wall and roof intersections.

7. At built-in gutters.

8. Where exterior material meets in other than a vertical line.

9. Where the lower portion of a sloped roof stops within the plane of an intersecting wall cladding in such a manner as to divert water away from the assembly in compliance with section R903.2.1.

10. At the intersection of the foundation and rim joist framing when the exterior wall covering does not lap the foundation insulation.

R703.8.1 Pan flashing of windows and doors.

Pan flashing shall be installed in accordance with the fenestration manufacturers installation and flashing instructions. Where flashing instructions or details are not provided, pan flashing shall be installed at the sill of exterior window and door openings. Pan flashing shall be sealed or sloped in such a manner as to direct water to the surface of the exterior wall finish or to the water-resistive barrier for subsequent drainage.

Exceptions:

1. Windows or doors installed in accordance with the manufacturers installation instructions which include an alternate flashing method.

2. Windows or doors in detached accessory structures.

3. Skylights, bow or bay windows.

4. Doors required to meet accessibility requirements that would prevent the installation of pan flashing.

5. Repairs or replacement of existing windows and doors.

6. When a method is provided by a registered design professional.

Statutory Authority: MS s 16B.59; 16B.61; 16B.64; 326B.02; 326B.101; 326B.106; 326B.13

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