Masonry construction fundamentals, material requirements, and inspection procedures.
2
hours
0.2
CEUs
Building Construction
1.7.1
This course covers material relevant to the following ICC certification exams:
Masonry construction fundamentals, material requirements, and inspection procedures.
Format
On-Demand Online
Delivery
Self-Paced
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24/7 After Enrollment
Certification
Certificate of Completion
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Contact our support teamUnderstand masonry unit selection, mortar type specifications, and grout requirements for different applications
Masonry construction relies on three primary components working together: units, mortar, and grout. Each has distinct material properties, specifications, and inspection requirements governed by IBC Chapter 21, which references TMS 402/602 (formerly ACI 530/ASCE 5) as the primary design and construction standard. Inspectors must understand the function and specification of each component to verify field compliance.
Concrete masonry units (CMU) are the most common masonry unit in commercial construction. Standard CMU dimensions are nominally 8 inches by 8 inches by 16 inches, with actual dimensions of 7-5/8 inches by 7-5/8 inches by 15-5/8 inches to accommodate 3/8-inch mortar joints. CMU must conform to ASTM C90 for load-bearing units, which requires a minimum net area compressive strength of 1,900 psi. Units are classified by weight: normal weight (125 pcf or more), medium weight (105 to 125 pcf), and lightweight (less than 105 pcf). Inspectors should verify unit markings and request manufacturer certifications confirming ASTM C90 compliance.
Clay brick units conform to ASTM C62 for building brick, ASTM C216 for facing brick, or ASTM C652 for hollow brick. Clay brick is classified by weather exposure: Severe Weathering (SW) for locations subject to freezing when saturated, Moderate Weathering (MW) for locations exposed to freezing but unlikely to be saturated, and Negligible Weathering (NW) for interior or protected applications. Selecting the wrong exposure grade for the climate and application is a common plan review deficiency that leads to premature deterioration.
Autoclaved aerated concrete (AAC) units are lightweight masonry units with a density of approximately 25 to 50 pcf, compared to 125 pcf for normal-weight CMU. AAC is governed by ASTM C1693 and provides excellent thermal insulation properties but lower compressive strength (typically 290 to 870 psi). AAC requires thin-bed mortar specifically formulated for the material and must be protected from moisture saturation with appropriate coatings or cladding.
Mortar types are designated by the letters M, S, N, O, and K (from the alternating letters of "MaSoNwOrK"), with Type M being the strongest and Type K the weakest. Each type is specified by either proportion or property specifications per ASTM C270. Type M mortar (2,500 psi minimum compressive strength) is used for below-grade applications and contact with earth. Type S mortar (1,800 psi) is the default for structural masonry, reinforced masonry, and exterior applications above grade. Type N mortar (750 psi) is suitable for general-purpose above-grade exterior and interior applications. Type O mortar (350 psi) is limited to non-load-bearing interior applications. The most common specification error is using Type N where Type S is required for structural or below-grade conditions.
Grout fills the cells of hollow masonry units to create solid cross-sections and to bond reinforcement to the masonry. Grout must conform to ASTM C476 and is classified as fine grout (sand aggregate only) or coarse grout (containing pea gravel up to 3/8 inch). The minimum compressive strength of grout is 2,000 psi per TMS 602. Grout must be fluid enough to flow without segregation into all cells and around reinforcement -- a slump of 8 to 11 inches is typical, which is significantly more fluid than structural concrete. Grouting must be performed in lifts not exceeding 5 feet for typical construction, with each lift consolidated using a mechanical vibrator or by puddling. Cleanout openings are required at the base of cells to be grouted when the grout pour height exceeds 5 feet, allowing inspection of the cell and removal of mortar droppings before grouting.
An inspector is reviewing a two-story commercial building with reinforced CMU exterior walls. The structural drawings specify Type S mortar, normal-weight CMU conforming to ASTM C90, and coarse grout at 2,000 psi minimum in all reinforced cells. During the wall inspection, the inspector verifies that mortar joints are 3/8 inch thick and that head and bed joints are fully filled in the face shells. The inspector checks that cleanout openings were installed at the base of the grouted cells and that mortar droppings have been removed before grouting. During the grout pour, the inspector observes consolidation of each 4-foot lift and verifies that the grout slump is within the 8 to 11 inch range. The inspector also collects grout specimens per ASTM C1019 for compressive strength verification.
Using the wrong mortar type for the application -- particularly Type N where Type S is required for structural or below-grade conditions -- is a common error that reduces the load capacity and durability of the wall. Failing to provide cleanout openings results in mortar droppings blocking grout flow and creating voids around reinforcement. Grouting with insufficient slump causes incomplete cell filling and reinforcement encasement. Laying units with dry, unprimed surfaces in hot weather causes rapid moisture absorption from the mortar, weakening the bond. CMU must be laid in a clean, dry condition per ASTM C90, but in hot or windy conditions, lightly fogging the units can prevent excessive suction that starves the mortar of hydration water.
Code Reference: IBC Chapter 21; TMS 402/602; ASTM C90, C270, C476 - IBC Section 2101 adopts TMS 402/602 as the governing standard for masonry design and construction. Mortar types and specifications are established by ASTM C270. Grout requirements follow ASTM C476, with minimum compressive strength per TMS 602.
Apply reinforcement placement, wall construction techniques, and prism testing requirements for masonry
Reinforced masonry combines the compressive strength of masonry units and grout with the tensile capacity of steel reinforcement. The reinforcement is placed in the grouted cells of hollow masonry units and anchored by development length into the grout, similar in concept to reinforced concrete but with distinct detailing requirements governed by TMS 402/602.
Reinforcement in masonry walls consists of vertical bars placed in grouted cells and horizontal bars placed in bond beam courses. Vertical reinforcement typically ranges from No. 4 to No. 9 bars, with the maximum bar size limited by cell dimensions -- the bar must have at least 1/4 inch clearance to the nearest cell face and 1 inch between bars in the same cell. Horizontal reinforcement is placed in bond beam blocks (units with the webs partially or fully removed) filled with grout, typically at 48 inches on center vertically per TMS 402 for walls in Seismic Design Category C or higher. Minimum reinforcement for empirical design in areas subject to seismic loads includes both vertical and horizontal bars at maximum spacing of 120 inches in each direction with a minimum total area of 0.002 times the gross cross-sectional area of the wall.
Wall construction follows specific bonding patterns. Running bond is the default pattern where each unit is offset by half its length from the course below. Stack bond, where vertical joints align, requires additional horizontal reinforcement at a maximum of 48 inches on center because the non-interlocking pattern provides no mechanical interlock for lateral force transfer. Inspectors should verify the bond pattern matches the approved plans and that the correct reinforcement details are provided for the pattern used.
Development length for reinforcement in masonry differs from concrete. TMS 402 Section 9.3.3.3 provides the equations for development length in tension, which is influenced by bar size, masonry compressive strength (f'm), bar yield strength, and the ratio of clear spacing to bar diameter. The minimum development length is 12 inches. Lap splice lengths are a minimum of the calculated development length or 12 inches, whichever is greater. Hooks are typically required at the tops and bottoms of vertical reinforcement where straight development length cannot be achieved.
Prism testing establishes the actual compressive strength of the masonry assemblage (f'm), which is the design strength used in structural calculations. Prisms are constructed from the same units, mortar, and grout that will be used in the project, then tested per ASTM C1314. A minimum of three prisms are required, and the f'm is the average net area compressive strength multiplied by height-to-thickness correction factors from the standard. As an alternative to prism testing, TMS 602 Table 1 allows the use of unit strength method, where f'm is determined from tables based on the compressive strength of the units and the mortar type. The unit strength method is simpler but generally yields more conservative (lower) f'm values than prism testing.
Flashing and weep holes are critical moisture management components in masonry wall systems. Through-wall flashing is installed at the base of the wall, above shelf angles, above and below window openings, and at any point where moisture may accumulate within the wall cavity. Weep holes are provided at 33 inches on center maximum in head joints directly above the flashing to allow collected moisture to drain to the exterior. Omitting or improperly lapping flashing is one of the leading causes of masonry wall moisture problems and related structural deterioration.
An inspector is on site for a reinforced CMU wall that will serve as a shear wall in Seismic Design Category D. The structural drawings call for No. 5 vertical bars at 32 inches on center with No. 4 horizontal bars in bond beam courses at 48 inches on center, using running bond with Type S mortar and f'm of 1,500 psi verified by prism testing. The inspector verifies that vertical bars are properly positioned in the center of the cells with adequate clearance, that the bars extend the required development length into the foundation and above the bond beam, and that the horizontal bars are properly lapped at splices. The inspector checks that mortar joints are consistently 3/8 inch and that bed joints are fully filled in the face shells. Before grouting, the inspector examines cleanout openings at the base of each grouted cell, confirms mortar droppings have been removed, and witnesses the grout placement in lifts not exceeding 4 feet with mechanical vibration of each lift.
Placing reinforcement off-center in the cell reduces the effective depth of the wall section for bending resistance. Bars pushed to one face of the cell can reduce the wall's out-of-plane capacity by more than 30%. Omitting bond beam reinforcement at the required spacing is a structural deficiency that must be corrected before further construction. Mortar bridging across cells (mortar fins protruding into the cell from bed joints) blocks grout flow and creates voids; inspectors should require cleanout inspection to detect this condition. Failing to brace masonry walls during construction before grout curing is complete has led to wall collapses. TMS 602 requires temporary bracing to resist wind and construction loads until the masonry achieves adequate strength.
Code Reference: TMS 402 Sections 9.3 and 7.3; TMS 602 Section 3.4 - Development length requirements for masonry reinforcement are in TMS 402 Section 9.3. Minimum reinforcement ratios and maximum spacing for seismic design categories appear in Section 7.3. Construction and grouting procedures are governed by TMS 602 Section 3.4.
Understand special inspection requirements for masonry construction per IBC Section 1705.4
IBC Section 1705.4 establishes the special inspection requirements for masonry construction, with the scope depending on whether the masonry is classified as Empirically Designed (Level 1) or Engineered (Level 2). The distinction matters because Level 2 quality assurance requires more frequent and rigorous inspection compared to Level 1.
Level 1 quality assurance applies to empirically designed masonry, glass unit masonry, masonry veneer, and masonry not part of the lateral force-resisting system. Level 1 requires periodic special inspection of the following items: proportioning of mortar materials, placement of units and mortar joint construction, placement of reinforcement and connectors, grouting operations (with verification that grout space is clean before grouting), and size and location of structural members. Periodic inspection means the inspector is not required to be continuously present but must be on site frequently enough to verify compliance.
Level 2 quality assurance applies to engineered masonry that is part of the lateral force-resisting system or designed using the strength design or allowable stress design methods of TMS 402. Level 2 requires continuous special inspection during preparation of mortar, grouting operations, and placement of reinforcement and connectors. The key distinction is that the inspector must be present during all grouting operations rather than just performing spot checks. Level 2 also requires verification testing of mortar and grout, typically including compressive strength testing of grout per ASTM C1019 and mortar testing per ASTM C780.
Material verification is a fundamental responsibility of the special inspector. This includes confirming that masonry units arrive with manufacturer certifications showing compliance with the applicable ASTM standard, that mortar materials (cement, lime, sand) match the approved mix design, and that reinforcing steel meets the specified grade and size. The inspector should check that materials are properly stored on site -- masonry units protected from rain saturation, cement stored off the ground and protected from moisture, and sand clean and free of organic contamination.
The special inspector for masonry must be qualified per IBC Section 1704.2.1 and approved by the building official. ICC certification as a Structural Masonry Special Inspector is the standard credential. The inspector's role requires independence from the contractor and direct reporting to the building official and the registered design professional. The inspector documents all observations, test results, and any deficiencies on standardized inspection reports that become part of the project record.
When special inspection reveals non-conforming work, the remediation path depends on the nature and extent of the deficiency. Minor mortar joint deficiencies can be tuckpointed. However, grouting deficiencies -- voids, incomplete cell filling, or misplaced reinforcement -- are extremely difficult to correct after the grout has set. In many cases, the only remedy is removal and reconstruction of the affected portion of the wall, which is why pre-grout inspection is so critical. The inspector should always verify grout space conditions before authorizing any grout placement.
A special inspector is assigned to a three-story reinforced CMU building in Seismic Design Category C. The structural engineer has designated Level 2 quality assurance on the construction documents. Before masonry construction begins, the inspector reviews the approved mix designs for mortar and grout, confirms that CMU certifications meet ASTM C90 requirements, and verifies that reinforcement matches the structural drawings. During construction, the inspector provides continuous inspection during grouting operations, verifying that each cell is clean, reinforcement is properly positioned, grout slump is within specification, and lifts are consolidated. The inspector performs periodic inspection of mortar joint construction, checking joint thickness, tooling, and head joint filling. Mortar specimens are collected per ASTM C780, and grout specimens per ASTM C1019, with results compared to the specified strengths. All reports are submitted to both the building official and the structural engineer.
Applying Level 1 quality assurance to masonry that functions as part of the lateral force-resisting system is a code violation requiring Level 2 inspection. Failing to inspect grout spaces before grouting is a missed opportunity that cannot be recovered -- once grout sets around mortar droppings and debris, the only assessment method is destructive testing or non-destructive evaluation techniques like impact echo testing. Not collecting mortar and grout specimens at the required frequency creates documentation gaps that can delay project approval. Special inspection reports that fail to distinguish between continuous and periodic inspection activities create confusion about whether the required level of oversight was actually provided.
Code Reference: IBC Section 1705.4; TMS 402/602 Quality Assurance provisions - Section 1705.4 references TMS 402/602 for the specific quality assurance levels and inspection requirements. Level 1 (periodic) and Level 2 (continuous for critical operations) quality assurance programs are defined based on the design method and structural function of the masonry.
This course equips building professionals with the knowledge needed to evaluate masonry construction materials, methods, and quality assurance programs. From unit selection and mortar specification through reinforcement placement, grouting procedures, and special inspection documentation, each module emphasizes the practical skills required for field verification of masonry work per IBC Chapter 21 and TMS 402/602. Understanding the interaction between units, mortar, grout, and reinforcement -- and the critical role of inspection at each stage -- enables inspectors to identify deficiencies before they become hidden within the completed assembly.