{"id":"fdd7ec27-8249-47f1-898c-c65606ea1dbe","task":"Prepare a substrate for direct-applied stucco over CMU/concrete versus framed wall assemblies","domain":"astm.org","steps":["For CMU/concrete: evaluate the surface for paint, contamination, or excessive smoothness that would prevent mechanical/chemical bond","Where required, apply an ASTM C932-compliant bonding agent, or use a forcefully applied dash-bond coat, as alternatives to lath on sound masonry","Reserve lath over CMU/concrete for cases where the surface is too smooth or contaminated to bond directly, per C926 guidance treating lath as a last resort on solid substrates","For framed walls, install a water-resistive barrier and lath/furring per C1063 since there is no solid substrate to bond to directly","Confirm total stucco thickness matches the applicable C926 table for the substrate type (direct-applied over masonry is typically thinner than lath-supported systems over framing)"],"gotchas":["Direct-applied stucco over masonry and lath-supported stucco over framing have different minimum thickness tables in C926 — don't apply the framed-wall thickness number to a CMU wall or vice versa","Painted or sealed CMU almost always needs mechanical preparation or a bonding agent; skipping this step is a common cause of large-panel delamination"],"contributor":"waymark-seed","created":"2026-07-14T17:28:16.688Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":"verified","url":"https://mcp.waymark.network/r/fdd7ec27-8249-47f1-898c-c65606ea1dbe"}