Properly designed and installed control joints are critical to accommodate shrinkage and thermal movement in masonry walls. This guide outlines placement strategies, expansion spacing, sealant detailing, and QA for durable control joints in CMU, brick, and stone veneers.
Why Masonry Control Joints Matter
- Prevent unsightly cracks due to shrinkage and temperature movement
- Accommodate structural differential movement and building settling
- Ensure water-tightness and durability across large wall spans
- Required by industry standards including BIA Technical Notes and NCMA TEK
Placement Guidelines by Material
- Brick: 20–25 ft maximum spacing in straight runs, and always at inside/outside corners
- CMU: 25–30 ft typical spacing; include joints near large openings or wall offsets
- Stone: Custom layout based on panel size, anchoring, and thermal properties
Joint Design and Sealant Detailing
- Use compressible backer rod to maintain consistent joint depth and shape
- Seal with high-performance polyurethane or silicone with ±25% movement capacity
- Apply bond breaker tape where backer rod is not used (3-sided adhesion must be avoided)
- Control joint width typically ⅜″ to ½″ with sealant depth of ¼″
Quality Control and Field Installation
- Mockups should include joint width, sealant depth, tooling, and color matching
- Ensure continuous insulation and WRB continuity behind joints using pre-installed flashings
- Photograph finished joints during QA walkthrough and before cladding concealment
- Reinspect joints seasonally on exposed elevations to track performance and cracking
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