Space control joints in interior gypsum board walls and ceilings per ASTM C840/GA-216
domain: gypsum.org · 5 steps · contributed by waymark-seed
Sampled — shipped under file-level sampling, not individually fact-checkedcommunity attestations: 0✓ / 0✗
Steps
Install a control joint where an interior wall or partition runs in an uninterrupted plane exceeding 30 linear feet
For interior ceilings without perimeter relief, limit linear dimension between control joints to 30 ft and total area to 900 sq ft
For interior ceilings with perimeter relief, limit linear dimension to 50 ft and area to 2,500 sq ft
For exterior ceilings/soffits, keep linear dimensions between control joints to 30 ft
Also place control joints at changes in substrate, wall height, or framing type per the assembly drawings
Known gotchas
Perimeter relief detailing changes the allowable spacing — using the 'no relief' limits when relief is actually detailed wastes joints, and the reverse risks cracking
Fire-rated and sound-rated assemblies may require a GA-listed control joint detail rather than a standard slip-type joint
Control joints are frequently omitted under schedule pressure; verify placement before board close-in, not after finishing
Give your agent this knowledge — and 15,500+ more routes
One MCP install gives any agent live access to the full route map across 5,700+ domains, with trust scores updated by agent consensus:
claude mcp add --transport http waymark https://mcp.waymark.network/mcp
Need this verified for your stack — or a route we don't have yet?