Masonry Structures
Introduction
Masonry structures combine units (concrete masonry, brick, stone) with mortar, grout, and often reinforcement to create durable walls, piers, and arches. They are common in schools, housing, industrial facilities, retaining walls, and veneers. Engineers value masonry for fire resistance, robustness, and architectural flexibility. This guide explains what masonry is, how it behaves, how to design and detail it, and what to verify during construction and inspections. We connect each decision to credible loads, defensible analysis, a continuous load path, and coordinated foundation design.
Masonry excels when materials, workmanship, reinforcement, and movement details work together—treat the wall as a system, not just stacked units.
What Are Masonry Structures & Why Use Them?
Structural masonry carries gravity and often lateral loads; veneers provide enclosure/finish over a structural backup. Properly detailed, masonry provides mass for acoustics and energy, inherent fire resistance, and architectural versatility. Modern reinforced masonry (RM) incorporates steel and grout to improve ductility and out-of-plane capacity.
- Advantages: Fire and impact resistance, thermal mass, robust partitions, and durable façades.
- Tradeoffs: Slenderness sensitivity, moisture/efflorescence risks without good detailing, and workmanship dependence.
- Best Fits: Schools/municipal buildings, residential and mixed-use podiums, stair/elevator cores, retaining walls, and resilient enclosures in high-wind regions.
Where Masonry Shines
Load-bearing shear walls in low- to mid-rise buildings, CMU stair cores with wind design demands, brick veneer rainscreens on steel or concrete frames, and gravity retaining walls with engineered drainage.
Materials, Units & Mortars
Masonry components determine strength, durability, and constructability. Unit selection, mortar type, and grout strategy should reflect exposure, loads, and aesthetic goals.
- Units: CMU (hollow or solid), clay brick, calcium silicate brick, natural or cast stone. Specify compressive strength, absorption, and dimensional tolerances.
- Mortar: Types M, S, N selected by required strength and workability. Softer mortars can improve compatibility with historic brick and reduce cracking.
- Grout: Fine or coarse grout to fill cells/cores; required for reinforced masonry to develop bars and achieve composite action.
- Reinforcement: Deformed bars in grouted cells or bond beams; joint reinforcement for crack control and veneer ties.
- Accessories: Ties/anchors, joint reinforcement, flashing, weeps, air/water barriers, control-joint accessories, and sealants.
Did you know?
Using compatible mortar (not just the strongest) often increases long-term durability by allowing micro-adjustments and reducing unit spalling.
Structural Systems
Choose the wall system early with architecture and MEP routing. Decide if the wall is load-bearing, shear-resisting, or veneer on a separate structural backup.
- Load-Bearing Walls: Reinforced CMU or reinforced brick with lintels/bond beams; stack walls across stories down to foundations.
- Shear Walls & Cores: Reinforced masonry walls provide lateral resistance; coupling beams over openings transfer shear.
- Veneer + Backup: Brick veneer or stone on CMU/steel/concrete backup with adjustable ties; provide a drained cavity and flashings.
- Arches & Vaults: Compression-dominant forms; use thrust-resistant supports or ties.
- Retaining Walls: Gravity, reinforced cantilever, or segmental systems—coordinate drainage and backfill properties.
Coordination Tip
Align openings and joist/beam bearings to minimize eccentricities. Repetitive modules speed layout and reduce field cutting and patching.
Design Fundamentals
Masonry design checks combined axial load and bending, shear, and out-of-plane stability. Reinforced sections often control ultimate strength; unreinforced (URM) requires strict limits on tensile stress and slenderness.
Combined Axial + Bending (Concept)
Slenderness (Concept)
- Strength: For RM, tension is carried by steel and compression by masonry—ensure ductile detailing.
- Serviceability: Crack control via joint reinforcement, control joints, and reasonable bar spacing; limit deflections for facades/partitions.
- Punching & Bearing: Check concentrated reactions at pilasters, lintel bearings, and ledger seats.
Design Workflow
Define loads → choose wall type (URM vs RM) → select thickness/reinforcement → check combined axial/bending and slenderness → verify out-of-plane/wind suction → detail control joints, ties, and flashing → coordinate with foundations.
Reinforcement, Grout & Anchorage
Bars in grouted cells (vertical) and bond beams (horizontal) provide strength, ductility, and crack control. Proper development, lap splicing, and clear cover are essential.
- Vertical Bars: Place in open cells aligned with loads; use bar chairs/spacers to maintain cover; lap or couple at story levels.
- Bond Beams: Knock-out units with continuous bars for diaphragm/collector forces and lintel action; coordinate with openings.
- Grout: Consolidate per lift height limits; verify absorption and temperature—grout must flow to avoid voids.
- Anchorage: Headed studs, dowels, and embedded plates transfer loads to diaphragms/frames; design edge distances and confinement.
- Veneer Ties: Adjustable, corrosion-resistant ties with proper embedment; maintain clear, ventilated cavities with continuous flashings and weeps.
Development (Concept)
Important
Partial grouting demands strict cell alignment and inspection; misplaced bars or unfilled cells critically reduce capacity.
Lateral & Out-of-Plane Design
Masonry walls frequently resist wind and seismic loads. Provide reliable diaphragm anchorage, collectors, and boundary elements. See our pages on wind design and seismic design.
- Shear Walls: Reinforced cores and boundary elements; control openings and provide confinement where compression is high.
- Coupling Beams: Steel or reinforced concrete beams across wall piers; diagonal bars or steel sections for high shear.
- Out-of-Plane: Check suction and positive pressure; design ties/backups for veneers; brace slender URM with anchors/frames if required.
- Diaphragms: Provide positive attachment of floors/roofs with collectors and chords; document anchor spacing and edge distances.
Arching & Thrust (Concept)
Joints, Moisture & Thermal Details
Movement and moisture control determine longevity. Detail for drying, drainage, and predictable movement.
- Control Joints: For CMU, provide regularly spaced vertical joints to manage shrinkage and temperature movement; coordinate with openings.
- Expansion Joints: For clay brick, expansion dominates—provide joints and slip details at shelf angles/backs.
- Flashing & Weeps: Continuous through-wall flashings above openings and at shelf angles; slope to exterior with weeps at 24–32 in. o.c. typical.
- Thermal Bridges: Shelf angles and anchors can bridge insulation—specify thermal breaks and continuous exterior insulation where required.
- Interfaces: Isolate dissimilar materials; align air/water barriers with window/door frames and roof-to-wall transitions.
Did you know?
Efflorescence signals moisture transport carrying salts to the surface—fix the water path (flashing, joints, caps) rather than just cleaning the stain.
Construction & QA/QC
Masonry performance depends on field quality. Submittals, mockups, testing, and special inspections verify that design assumptions are achieved.
- Submittals: Unit/mortar/grout data, bar schedules, ties/anchors, flashing details, and shop drawings tied to the project’s analysis.
- Mockups: Confirm appearance, joint tooling, flashing, weeps, and control-joint execution before production.
- Testing: Prism/unit tests, grout/cylinder tests as applicable; verify bar placement and cell grout consolidation.
- Weather: Cold- and hot-weather procedures; keep units and mortar within specified temperature/moisture limits.
- Documentation: Grout lift logs, inspection photos, and as-built bar/anchor layouts support future maintenance and alterations.
Important
Do not cut chases or MEP openings in bearing or shear walls without engineering review. Small cuts can create large eccentricities and reduce capacity.
Inspection, Assessment & Repair
Over time, masonry can exhibit cracking, spalling, and moisture ingress. An inspection plan preserves capacity and serviceability—see our overview of structural failure modes.
- Routine Checks: Map cracks (location/width), examine joint sealants and flashings, probe for unfilled cells or loose ties in veneers.
- NDE & Testing: IR scans for moisture, borescope in cells, pull tests for anchors, and petrography for historic masonry compatibility.
- Repairs: Repointing with compatible mortar, grout injection for cracks, replacement of corroded anchors, and FRP/steel strengthening where needed.
- Maintenance: Keep caps, copings, and sealants functional; ensure weeps are open; clean efflorescence only after correcting moisture paths.
Codes, Standards & Trusted References
Anchor your work to authoritative, stable resources:
- International Code Council (ICC): Model building codes and structural provisions. Visit iccsafe.org.
- ASTM International: Unit, mortar, grout, and tie/anchor standards and test methods. Visit astm.org.
- The Masonry Society (TMS): Design standards and detailing guides. Visit masonrysociety.org.
- NIST: Research on resilience and materials performance. Visit nist.gov.
- FEMA: Guidance on seismic evaluation/retrofit of URM. Visit fema.gov.
For connected topics, review structural loads, perform rigorous analysis, coordinate wind and seismic design, and deliver reactions into robust foundations. See also building materials for system comparisons.
Frequently Asked Questions
When should I choose URM vs reinforced masonry?
URM is suitable for low, lightly loaded walls where tension is negligible and out-of-plane loads are small. For most modern structures and any seismic/wind demands, reinforced masonry provides ductility and higher capacity.
How do I control cracking?
Provide control/expansion joints at rational spacing, joint reinforcement, and reasonable bar spacing; limit restraint at interfaces; keep moisture managed to reduce shrinkage stresses.
What causes veneer failures?
Missing or corroded ties, blocked cavities, discontinuous flashing, and inadequate weeps. Design for drainage/ventilation, use stainless ties in coastal/deicing regions, and inspect tie installation.
Can I create large openings in bearing masonry?
Yes—with engineered lintels or transfer beams, adequate jamb reinforcement, and staged shoring. Recheck foundation reactions and the building’s lateral system after changes.
Is masonry sustainable?
Masonry’s durability and thermal mass can reduce lifecycle impacts. Use SCMs in mortar/grout, detail for longevity, and design for maintainable, easily inspectable assemblies.
Key Takeaways & Next Steps
Masonry structures deliver fire resistance, durability, and architectural quality when the system is designed holistically: loads, slenderness, reinforcement, moisture/thermal details, and high-quality construction. Start with realistic loads, size walls for combined axial and bending with rational eccentricities, verify out-of-plane stability, provide continuous diaphragm anchorage, and detail flashing and joints that keep the wall dry.
Continue with our guides on structural analysis, confirm the load path to foundations, and schedule thorough inspections. For standards and research, rely on ICC, ASTM, TMS, NIST, and FEMA. Thoughtful system selection + sound detailing + disciplined QA/QC = masonry that performs for decades.