Masonry Construction Requires Specific Details at Every Opening, Joint, and Drainage Location - and They Must All Appear in the CD Set
Masonry wall construction - whether brick veneer over CMU backup, full brick walls, CMU bearing walls, or architectural masonry units - requires a specific set of construction details that go beyond simple wall section drawings. The details address how openings are spanned (lintels), how masonry veneers are tied to backup walls (ties and anchors), how thermal and moisture movement is accommodated (control joints and expansion joints), and how water is managed within the cavity and drained to the exterior (weepholes and flashing). Each of these details, if omitted or detailed incorrectly, leads to specific failure modes: lintel deflection causing cracked masonry above openings; tie failure allowing veneer to separate from backup; control joint omission causing cracking from thermal movement; omitted weepholes causing moisture accumulation in the cavity that degrades backup insulation and leads to interior moisture problems. The ARE PDD exam tests masonry construction details as part of the construction document coordination and building envelope content area.
Lintels
Lintels span openings in masonry walls - windows, doors, and any other horizontal opening. In brick veneer over CMU backup systems, separate lintels are typically required for each leaf: a steel angle lintel for the brick veneer (carrying the brick above the opening) and a CMU bond beam or structural lintel for the CMU backup (carrying the backup wall above). Steel angle lintels are sized for the masonry span and load and must have adequate bearing length at each end (typically 8 inches minimum). In full brick walls and CMU bearing walls, steel angle or concrete masonry unit bond beam lintels carry the full wall load. The architect must coordinate lintel size and bearing with the structural engineer and ensure lintels are shown in all elevation and section details at openings.
Wall Ties and Anchors
Brick veneer over CMU or steel stud backup requires ties or anchors connecting the veneer to the backup at regular intervals. Standard tie spacing: 16 inches vertically, 24 inches horizontally (one tie per 2.67 SF of wall area) per MSJC (Masonry Standards Joint Committee) requirements. At openings and at top of wall, ties are spaced more closely. The air space between veneer and backup must be at least 1 inch (to allow mortar droppings to clear without bridging the cavity) and not more than 4.5 inches for standard ties. Thermally broken ties (stainless steel or polymer-insulated) reduce thermal bridge losses through the tie; required in high-performance wall assemblies.
Control Joints and Expansion Joints
CMU walls require control joints to accommodate thermal and moisture movement - CMU shrinks as it cures and expands and contracts with temperature. Without control joints, shrinkage and thermal stresses cause random cracking at wall weak points (window corners, door jambs). Control joint spacing: maximum 25-30 feet horizontally; at all changes in wall section and height. Brick veneer requires expansion joints to accommodate moisture expansion of brick (brick expands over time as it absorbs atmospheric moisture; opposite of CMU which shrinks). Expansion joints in brick: maximum 20-25 feet horizontally; at all building expansion joints. Joint materials: polyurethane or silicone sealant over a compressible backer rod.
Weepholes and Flashing
Water that enters the cavity must be drained to the exterior through weepholes at the base of the veneer (above flashing at every horizontal barrier: bottom of wall, above lintels at window heads, at shelf angles). Weephole spacing: one per masonry unit (approximately 16 inches on center) or through open vertical joints; minimum 3/16 inch opening. Flashing is required at the base of the veneer and at every shelf angle to collect water that enters the cavity and direct it to the weepholes. Flashing material: rubberized asphalt, modified bitumen, through-wall sheet metal, or termination bar and fluid-applied; must be sloped toward the weepholes to drain.
Key Exam Points
- Lintel: spans masonry opening; separate for veneer and backup in cavity wall systems; 8-inch min bearing.
- Wall ties: 16-inch vert x 24-inch horiz spacing; 1-inch min cavity; 4.5-inch max for standard ties.
- Control joints (CMU): accommodate shrinkage and thermal movement; max 25-30 ft spacing.
- Expansion joints (brick): accommodate moisture expansion; max 20-25 ft spacing.
- Weepholes: drain cavity water; one per masonry unit (approx 16-inch oc); above flashing at every horizontal barrier.
AREprep's PDD building envelope and construction documents content covers masonry details comprehensively - lintels, ties, flashing, control joints, and weepholes - with clear diagrams and code reference sources - giving ARE PDD candidates the masonry construction detail knowledge the exam tests in construction document coordination questions about building envelope systems.
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