Stucco control joints — break the wall into ≤144 sq ft panels so it doesn’t crack
Cement stucco shrinks as it cures. Control joints break the wall into panels ≤144 sq ft (≤18 ft any dimension, ≤2.5:1) so the shrinkage relieves at the joints instead of cracking the field randomly.
What this diagram shows
Two stucco wall elevations compared. Without control joints, one large unbroken field cracks randomly as the cement stucco shrinks while curing. With control joints, the wall is divided into small panels so the shrinkage relieves at the joints instead of as wandering cracks. ASTM C1063 limits each panel to no more than 144 square feet, no dimension over 18 feet, and a length-to-width ratio no greater than 2.5 to 1, with joints at every story line and substrate change.
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3-coat / 2-coat / 1-coat stucco take-off — bags per coat, lath, weep screed, casing, control joints. Per IRC R703.7 / ASTM C926. Free.
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