Figure 7-19.-Open-frame construction.(fig. 7-19), nails are driven one-half their length into thewood. Spacing should be 5 to 6 inches OC from thebottom. Nails should be placed at all corners andopenings throughout the entire structure on the exterior.The next step is to place wire on the nails. This iscalled installing the line wire. Next, a layer of water-proof paper is applied over the line wire. Laps should be3 to 4 inches and nailed with roofing nails. Install wiremesh (stucco netting), which is used as the reinforce-ment for the stucco.Furring nails (fig. 7-20) are used to hold the wireaway from the paper to a thickness of three- eighths ofan inch. Stucco or sheathed frame construction is thesame as open frame except no line wire is required. Theopen and sheathed frame construction requires threecoats of 3/8-inch scratch coat horizontally scored orscratched, a 3/8-inch brown coat, and a 1/8-inch finishcoat.Stucco is usually applied in three coats. The firstcoat is the scratch coat; the second the brown coat; andthe final coat the finish coat. On masonry where noreinforcement is used, two coats maybe sufficient. Startat the top and work down the wall. This prevents mortarfrom falling on the completed work. The first, or scratch,coat should be pushed through the mesh to ensure themetal reinforcement is completely embedded formechanical bond. The second, or brown, coat should beapplied as soon as the scratch coat has setup enough tocarry the weight of both coats (usually 4 or 5 hours). Thebrown coat should be moist-cured for about 48 hoursand then allowed to dry for about 5 days. Just before theapplication of the finish coat, the brown coat should beuniformly dampened. The third, or finish, coat isfrequently pigmented to obtain decorative colors.Although the colors may be job-mixed, a factory-prepared mix is recommended. The finish coat maybeapplied by hand or machine. Stucco finishes areavailable in a variety of textures, patterns, and colors.Surface PreparationBefore the various coats of stucco can be applied,the surfaces have to be prepared. Roughen the surfacesof masonry units enough to provide good mechanicalkey, and clean off paint, oil, dust, soot, or any othermaterial that may prevent a tight bond. Joints may beFigure 7-20.-Several types of furring nails.7-17
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