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Masonry construction guide

Understanding masonry systems, details, and common abbreviations on construction drawings.

Masonry remains one of the most widely used construction materials worldwide. From structural CMU walls to decorative brick veneer, masonry appears on most commercial building projects. Understanding how masonry is detailed on drawings, reinforcement patterns, joint types, flashing systems, and structural connections, is essential for effective plan review and coordination.

Masonry System Types

Concrete Masonry Units (CMU)
Sizes
4", 6", 8", 10", 12" nominal width
Weight
Normal weight (~135 pcf) or lightweight (~105 pcf)
Strength
f'm 1,500-3,000 psi typical
Common Uses
Structural walls, fire walls, foundation walls, utility buildings, backup walls for brick veneer
Clay Brick
Sizes
Modular (2-2/3" × 4" × 8"), utility, king, etc.
Weight
120-130 pcf
Strength
Grade SW (severe weathering) or MW (moderate)
Common Uses
Exterior veneer, accent walls, historical restoration, paving
Natural Stone
Sizes
Varies, ashlar (cut) or rubble (irregular)
Weight
140-175 pcf depending on stone type
Strength
Varies widely by stone type
Common Uses
Exterior cladding, accent features, landscape walls, countertops
Glass Block
Sizes
6", 8", 12" square modules, 4" thick typical
Weight
Light, hollow units
Strength
Non-structural only per most codes
Common Uses
Daylighting walls, partitions, shower enclosures, stairwells

Reinforcement Requirements

Reinforced masonry uses steel rebar placed in grouted cells (vertical) and bond beams (horizontal) to resist lateral and gravity loads. Reinforcement requirements depend on seismic design category, wall function, and loading.

Vertical Reinforcement
Rebar placed in grouted CMU cells. Typical: #4 or #5 bars at 32" to 48" on center for load-bearing walls. Seismic zones require closer spacing (24" or 16" OC).
Horizontal Reinforcement (Bond Beams)
U-shaped or knocked-out CMU courses filled with grout and rebar. Required at top of wall, floor/roof bearing, above/below openings, and at maximum 48" vertical spacing in seismic regions.
Joint Reinforcement
Ladder or truss-type wire reinforcement placed in mortar joints at 16" vertical spacing. Provides crack control and ties multi-wythe walls together.
Grouting
Fluid concrete fill placed in reinforced cells. Can be full-grout (every cell) or partial-grout (only cells with rebar). Full grout increases fire rating and structural capacity.

Control Joints and Expansion Joints

Movement joints are critical in masonry to prevent uncontrolled cracking. CMU shrinks as it cures (control joints), while clay brick expands over time (expansion joints).

CMU Control Joints

Accommodate shrinkage as CMU dries after manufacturing. Placed as vertical joints through the wall.

  • Maximum spacing: 25 feet (less in arid climates)
  • Required at window/door jambs, wall intersections, and offsets
  • Use pre-formed gaskets or backer rod with sealant
  • Horizontal reinforcement must be interrupted at control joints

Brick Expansion Joints

Accommodate irreversible moisture expansion of clay brick (up to 0.05%). Placed as full-depth separations.

  • Maximum spacing: 20-25 feet typical
  • Required at corners, setbacks, and material transitions
  • Compressible filler with sealant
  • Must align with control joints in CMU backup

Lintels, Bond Beams, and Bearing

Steel Lintels (Angles)
Support masonry above openings. Sized by span and tributary load. Minimum bearing: 4" each end. Galvanized or painted per exposure. Loose lintels rest on jamb masonry; shelf angles are continuous and support full wall courses.
Masonry Bond Beams
Reinforced concrete-filled courses that act as horizontal beams. Used as lintels over openings and as continuous horizontal reinforcement. Typically shown as solid-hatched courses on wall sections.
Shelf Angles
Steel angles attached to the structure that support masonry veneer at each floor. Required when veneer height exceeds code limits (typically 25-30 feet). Horizontal expansion joint below shelf angle accommodates differential movement.
Bearing Details
Where masonry walls bear on foundations or structural elements. Minimum bearing width: full wall thickness. First course must be solid or fully grouted. Verify bearing elevation against structural drawings.

Flashing and Weep Holes

Moisture management in masonry relies on flashing to collect water that penetrates the veneer and weep holes to let it drain out. Missing or improperly installed flashing is one of the most common causes of masonry wall failures.

  • Through-wall flashing required at: base of wall, above all openings, below shelf angles, at roof-to-wall intersections, and above any penetrations
  • Flashing must have end dams (turned-up edges) at terminations to prevent lateral water migration
  • Weep holes spaced at maximum 24" on center (some codes allow 33"), placed directly above flashing
  • Weep hole types: open head joints, cotton wicks, plastic tubes, or cellular vents
  • Mortar collection device (mesh or foam) above flashing prevents mortar droppings from blocking weep holes
  • Flashing material must be compatible with mortar, copper, stainless steel, rubberized asphalt, or HDPE

Common Masonry Abbreviations

CMU
Concrete Masonry Unit
BB
Bond Beam (horizontal reinforced course)
CJ
Control Joint (vertical expansion relief)
EJ
Expansion Joint (full separation)
V/H
Vertical/Horizontal reinforcement
GRT
Grout (fills cells with reinforcement)
f'm
Specified compressive strength of masonry
WH
Weep Hole (moisture drainage)
FL
Flashing (moisture diversion sheet)
TYP
Typical (applies to all similar conditions)
NF
Non-load bearing (partition wall)
LB
Load Bearing (structural wall)
RJ
Rake Joint (recessed mortar joint)
CK
Caulk or Sealant

Sources

TMS 402/602, Building Code Requirements and Specification for Masonry Structures

BIA Technical Notes on Brick Construction, Brick Industry Association

NCMA TEK Notes, National Concrete Masonry Association

Keep exploring

Related structural and detail references.

How to Read Structural Drawings

Structural plan interpretation guide.

Waterproofing Details Guide

Moisture protection for masonry walls.

Construction Joint Types

Control, expansion, and isolation joints explained.

Concrete Inspection Checklist

Quality checks for concrete and masonry foundations.

Automate masonry detail review

Helonic's AI can verify masonry reinforcement schedules against structural drawings, flag missing flashing details at critical locations, and check control/expansion joint spacing compliance.