New Mexico Administrative Code
Title 14 - HOUSING AND CONSTRUCTION
Chapter 7 - BUILDING CODES GENERAL
Part 3 - 2021 NEW MEXICO RESIDENTIAL BUILDING CODE
Section 14.7.3.15 - CHAPTER 7 WALL COVERING

(1) Section R703.7.2 Plaster. Insert the following at the end of the second paragraph: 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. All residual plaster or stucco material that accumulates at the base of the wall shall be removed before it is allowed to cure and no horizontal plaster or stucco material shall remain on the adjacent grade, footing, footing trench or, when provided, weep screed. All residual stucco material shall be removed from roof surfaces and roof substrates before it is allowed to cure. The proportion of aggregate to cementitious materials shall be as set forth in Table R702.1(3). Exception: Exterior plaster may be continued below the weep screed to below grade provided there is a complete break in the drainage plane of the building at the location of the horizontal weep screed. Weep holes in the screed shall not be plugged during the application of plaster materials used to cover foundation insulation.

(2) Section R703.7.2.1 Weep screeds. Delete the text of this section of the IRC and substitute with the following: When an approved acrylic based exterior finish stucco system or acrylic based color coat is applied, a minimum 0.019 inch (0.48 mm) (No. 26 galvanized sheet gage), corrosion-resistant weep screed or plastic weep screed, with a minimum vertical attachment flange of three half inches (89 mm) shall be provided at or below the foundation plate line on exterior stud wall in accordance with ASTM C 926. The weep screed shall be placed a minimum of four inches (51mm) above the earth or half inch 13 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 lap the attachment flange of the weep screed. Weep screeds are not required under covered porches or covered patios.

(3) Section R703.7.3 Water-resistive barriers. Delete this section of the IRC and substitute with the following: Water-restive barriers shall be installed as required in Section R703.2 and where applied over wood-based sheathing, shall include a water-resistive vapor-permeable barrier with performance at least equivalent to two layers of Grade D paper. Such felt or material shall be applied horizontally, with the upper layer lapped over the lower layer not less than two inches (51mm). Where vertical joints occur, the material and or felt shall be lapped not less than six inches (152mm).