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Three-Coat Stucco

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    Harry Whitver

    1. Drainage Plane

    To shed incidental moisture intrusion from a wood-framed wall, assemble a drainage plane consisting of wood and/or foam sheathing that covers the entire wall (not just openings and corners), followed by a properly flashed and taped housewrap, a metal weep screed along the bottom of the wall, and at least one layer of building felt to serve as a bond break.
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    Harry Whitver

    2. Lath Layer

    Fasten a self-furring metal lath over the drainage plane to the structural components of the framed wall (not just the sheathing), making sure the stand-offs are against the wall to hold the lath away from that surface at least ? of an inch. Install control joints at least every 144 square feet and ideally aligned with openings, between floors, and at the garage-house intersection.
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    Harry Whitver

    3. Scratch Coat

    A properly proportioned mix of Portland cement, stucco-grade sand, and water is essential to create a strong foundation for the cladding system. Mix and then remix after 20 minutes before applying to a uniform, ½-inch thickness, then scratch the surface so it will bond with the brown coat. Wait 12 hours before hydrating at least once so that the coat retains water for at least 48 hours to properly cure.
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    Harry Whitver

    4. Brown and Finish

    With a little more sand than the scratch coat, a smooth brown coat is applied to a uniform ?-inch thickness and hydrated like the scratch coat. After it cures, apply the finish coat at a uniform ?-inch thickness, perhaps with a color additive in the mix; texture as desired and hydrate to ensure a proper cure and to mitigate surface cracks.

Stucco has long been a popular cladding for new homes, in markets ranging from Florida to California and at every price point.

But during the building boom, and even the decade before it, builders got a little sloppy with newfangled EIFS and one-coat systems that were designed to save energy and labor costs but often ended up on 60 Minutes or in a courtroom instead.

As building quality makes a comeback as part of an overall push to improve housing performance and durability, the old yet reliable three-coat stucco application is making a comeback. Sure, it takes more time, but would you rather extend the schedule a few days to do it right from the get-go or suffer the consequences of a callback—or worse?

Consider the basic steps below for a proper three-coat stucco job, and consult with your mason or stucco contractor on the finer details to ensure a long-lasting application.