MASONRY GLOSSARY
Want to learn more about the materials and accessories that make masonry wall systems work? Search our glossary of essential terms for a primer on the components of well-built masonry walls.
Abutment
The supporting wall or pier that receives the thrust of an arch.
Aggregate
Granular material consisting of normal weight or lightweight particles used with a cementing medium to form concrete masonry, mortar or grout.
American Institute of Architects (AIA)
The American Institute of Architects is the voice of the architecture profession dedicated to serving its members, advancing their value and improving the quality of the built environment.
American Society for Testing and Material (AS
A global forum for the development of consensus standards.
American Society of Civil Engineers (ASCE)
A society working to represent civil engineers and provide quality information and resources on technical and professional issues.
Anchor Bolts
Threaded bolt placed in grouted masonry unit opening. Used to fasten wood will, beam or other structural support to wall top.
Anchors
Metal or strap usually made of brass, stainless steel or galvanized steel. Anchors are used to tie a wall (brick, block or stone) to another structure.
Apprentice
Individual indenture (contracted) to a training program run by a Joint Apprenticeship and Training Committee (JATO) in the building trades.
Arch
A section of masonry work that spans an opening and supports not only its own weight, but also the weight of the masonry work above it.
Backer Rod
A flexible foam rod tubing either open or closed call used to maintain a constant joint design. It maintains two sided adhesion required for all proper sealant joints.
Barrier Masonry Walls
The modern masonry barrier wall is often single wythe construction where the exterior surface is designed to resist weather penetration.
Most masonry used throughout history was built as a barrier wall, relying on the wall's mass and completely filled mortar joints to resist water penetration. The modern masonry barrier wall is often single wythe construction where the exterior surface is designed to resist weather penetration. Concrete masonry units as well as hollow clay masonry units are used to construct these types of structures. Different surface treatments are used to assist in creating the barrier such as opaque elastomeric coatings and clear water repellants. Additionally, the use of integral water repellants in the concrete masonry units as well as in the mortar has proven beneficial in reducing moisture penetration.
Resources
Basket Weave Bond
Module groups of brick laid at right angles to those adjacent.
Bat (Batt)
A piece of brick usually half the full size or smaller.
Beaded Joints
See Movement Joints
Bed
The bottom side of a brick or block as it has been laid in the wall.
Bed Joints
Horizontal mortar bed on which a masonry unit has been laid.
Bevel
The incline of one surface of the same body with the angle being other than a right angle.
Bond
Pattern of laid masonry units; adhesion between mortar and masonry units; tying together parts of two or more wythes of masonry walls by overlapping masonry units.
Bond Beam
A bond beam is a horizontally reinforced element in a masonry wall that provides resistance to shear loads and also helps distribute lateral loads throughout the wall section.
A bond beam is a horizontally reinforced element in a masonry wall that provides resistance to shear loads and also helps distribute lateral loads throughout the wall section. Reinforcement is placed in special bond-beam units that have reduced-height cross webs and grouted solid. Bond beams are typically one course tall; grout is prevented from filling cells below by placing a mesh-type grout stop material in the bed joint underneath the bond beam. Bond beams are usually seen at the top of foundation walls, tops of walls, and at each floor diaphragm connection. Intermediate bond beams are often required in higher seismic design categories.
Structural Considerations
Bond beams are sometimes arbitrarily placed in walls as a stiffening or tie element, and are recommended at tops of walls, floor connections, and top of foundation walls. Intermediate bond beams are normally not necessary unless required to resist shear stresses or to fulfill minimum seismic reinforcement requirements.
Construction Concerns
The intersection of a bond beam with vertically reinforced cells can be very congested, with multiple bars in each direction. Minimize the amount of bond beam steel to improve grout flow and permit proper grout consolidation.
Use L-shaped corner bars, lapped with the bond beam steel, to provide continuity around building corners.
What to Do at Expansion and Control Joints
For most conditions it is best to cut bond beam reinforcement at expansion joints and control joints. The exception to this rule is at floor diaphragms, where the bond beam may be acting as the diaphragm chord and must be continuous down the wall. It is possible to detail a slip connection around bond beam reinforcement, but normally, lateral continuity across movement joints is not required for structural performance.
Resources
Bond Stone
Stone or masonry unit that projects back from the facing wall into a backup wall. Bond stone is designed to tie the two walls or wythes together. A bond stone may not project completely through the two walls or wythes.
Boot Rod (sled runner)
A tool used to finish joints - a longer jointer with a wood handle used for bed joints.
Brick
A molded rectangular block of clay baked by the sun or in a kiln until hard and used as a building and paving material.
Types and Sizes
Clay brick is one of the oldest building materials used by man. Brick is manufactured from naturally-occurring surface clays, shales, and fire clays. Fired to a high temperature, brick is inherently resistant to moisture attack, fire, and insects.
Brick may be completely solid or have cores or cells for reinforcement placement.
Typical brick sizes include (width x height x length):
- Modular: nominal 4 x 2 1/3 x 8, actual 3 5/8 x 2 ¼ x 7 5/8
- Utility: nominal 4 x 4 x 12, actual 3 5/8 x 3 5/8 x 11 5/8
- Engineer: nominal 4 x 3 x 8, actual 3 5/8 x 2 5/8 x 7 5/8
- King: nominal 4 x 2 1/3 x 10, actual 3 5/8 x 2 ¼ x 9 5/8
- Hollow (reinforceable): nominally 4” high x 12” and 16” long, widths of 4, 6, 8, 10, and 12 inches.
Actual brick sizes are slightly less than nominal sizes to account for the mortar joint thickness; mortar head and bed joints are normally specified at 3/8” thick for brick masonry.
Colors, Surface Textures
Brick come in a wide range of colors and textures. Many brick colors are derived from the source materials and color is consistent through the entire brick section. Some manufacturers get color variations by applying a surface slurry or sand coating to the exposed brick face.
ASTM Requirements for Brick
A series of ASTM specifications list required properties for solid building brick, veneer brick, and hollow reinforceable brick. Brick durability is ensured by requirements for minimum compressive strength and maximum absorption.
Weather Exposures
Brick with greater resistance to freezing damage are required for use in exterior applications throughout much of the U.S. Use Grade SW brick for severe weather exposures and Grade MW brick for moderate weather exposure and interior applications. See ASTM brick standards for more information on weather regions throughout the U.S. and the proper type of brick to use on your project.
Surface Finish Grades
Some variations in brick dimensions are expected and ASTM brick specifications include limits on uniformity, acceptable chippage, and cracks. Standard veneer brick designations, for example, range from Type FBS (general use) to intentionally roughened (tumbled brick) Type FBA to high precision, very uniform Type FBX brick.
Brick Tests
ASTM C67, Standard Test Methods for Sampling and Testing Brick and Structural Clay Tile, contains a series of tests used to measure brick strength, absorption, dimensions, and durability properties.
Specifying Brick
Brick Buggies
Carts used to covey material (palletized or packaged) on scaffolds or building floors either hand or power driven.
Brick Industry Association (BIA)
National trade association representing distributors and manufacturers of clay brick and suppliers of related products and services.
Brick Set/Bolster
A tool used for cutting brick. A brick set is beveled on one side and straight on the other.
Buttering
Place mortar on a masonry unit with a trowel.
Castables
Refractory material in a hydraulic setting bind.
Caulk (Caulking)
Sealing material, the process of sealing cracks around doors, windows and other cracks with a caulking gun.
Cavity Wall
A wall built in two wythes of masonry tied together with a continuous air space in between.
Cavity Wall Ties
Metal ties or bonding units used to tie together the wythes on a cavity wall.
Cell Clip
Cut brick piece or section.
Closure
Supplementary or short length used at corners or jambs to maintain bond patters.
Coarse Aggregate
Material predominantly retained on the No. 4 sieve.
Column
Vertical support member.
Compressive Strength
Another term for dead or live loads, vertical forces on a masonry structure.
Concave Joint
A mortar joint tooled with a round jointer. See Movement Joints.
Concrete
A hard, strong construction material consisting of sand, conglomerate gravel, pebbles, broken stone, or slag in a mortar or cement matrix.
Concrete Block
Concrete masonry units (CMU) are made from a combination of cementitious materials, aggregate, admixtures, and water.
Types and Sizes
Concrete masonry units (CMU) are made from a combination of cementitious materials, aggregate, admixtures, and water. Materials are mixed at the block plant, placed into molds, and vibrated. Very dry mixes are used to permit rapid mold stripping. Concrete masonry units are cured at the block plant to ensure proper hydration of cementitious materials. CMU may include pigments for color variations or integral water repellents.
Concrete masonry units are manufactured in a wide range of sizes and configurations, to be used for masonry veneers and load bearing or reinforced masonry construction. Hollow units for reinforced masonry have a standardized length of 16 inches and a height of either 4 or 8 inches. Through-the-wall thicknesses are manufactured to be 4, 6, 8, 10, or 12 inches. Actual CMU sizes are slightly less than the listed nominal sizes to account for a 3/8” mortar joint thickness.
Colors, Surface Textures
A wide range of colors and surface textures are available for architectural variation. Colors range from the standard “cement gray” to white, from tan to red to dark brown and black. Most block manufacturers will mix a pigment into the concrete mix, creating a color consistent through the entire unit thickness.
Split-face or “rock-face” units are especially popular. Other surface finishes include smooth ground-face, ribbed units, and scored units.
Contact your local supplier for availability in your area.
ASTM Requirements for Concrete Block
ASTM contains a series of specifications for different concrete masonry units. Most common is ASTM C90, Standard Specification for Loadbearing Concrete Masonry Units, which contains requirements for strength, absorption, dimensions, and durability properties.
Concrete Block Tests
ASTM C140, Test Methods for Sampling and Testing Concrete Masonry Units, contains a series of test methods used to measure CMU strength, absorption, dimensions, and durability properties.
Specifying Concrete Block
Concrete Block Veneer
Material requirements for concrete veneer are the same as those for structural units.
Types and Sizes
Concrete masonry is becoming an increasingly popular choice for masonry veneer applications. Material requirements for concrete veneer are the same as those for structural units. It is most effective to use thinner 3” or 4” units for masonry veneer. In some markets 4” split-face units are widely available and make an attractive veneer. Half-height or scored units may also be used to reduce the apparent scale of the veneer.
Control Joint
Vertical joint made in the wall to allow for shrinkage movement. Used to prevent random cracking of the wall caused by contraction. See also expansion joint.
Corrugated Wall Ties
Galvanized strips of metal cut 1 inch wide in varying lengths. Used in wall reinforcing.
Crown
High point or apex of curving arch.
Dead Load
A type of vertical force applied on a wall by the weight of the building.
Deflection
Deviation from normal position or from zero.
Density
The quality of being dense, close or compact.
Dowels
A cylindrical piece of steel, either smooth or threaded used to hold stone in place. Dowels can be set in sealant, mortar or epoxy.
Drainage Cavity
The internal drainage cavity is designed to intercept any water that penetrates through the exterior wythe.
Masonry cavity walls consist of two wythes of masonry separated by an airspace connected by corrosion resistant ties. The internal drainage cavity is designed to intercept any water that penetrates through the exterior wythe. Flashings, weep holes and waterproof membranes are used at the base of the cavity to direct water out of the cavity and prevent water from getting into the building. A 1" minimum clear space is required by code.
Mortar Fins & Droppings
Mortar droppings from the construction process can fill or bridge across drainage cavities, clog weep holes and prevent the escape of water from the cavity. Mortar fins that bridge the cavity, usually at wall ties, can act as conduits for water to the interior wythe. Masonry cavities should be built free of excess mortar that may impede moisture flow or permit water to saturate the backup.
Mortar Deflectors
Mortar deflectors or nets are often used at the base of cavities to catch mortar droppings which would otherwise clog cavities and weeps and prevent escape of water. Many materials are used for this function including netting or mesh of various types that catch the mortar and prevent it from settling at the base of the cavity. Pea gravel is also traditionally used which, being larger than weep tubes, holds the mortar away from the weeps and keeps them clear. This is a less effective method and mesh or net is preferred.
Drip
A projecting piece of material shaped to throw off water, prevent it from running down a wall or running back under a projection.
Dry Pressed Brick
Brick formed in molds under high pressure from relatively dry clay (5 to 7 percent moisture content).
Dry Saw
Dry cutting blade. If used without water can produce enormous amounts of dust.
Efflorescence
A deposit of white powder on the surface of masonry which comes from the leaching of water soluble salts in the masonry by evaporation of water.
Elastic
Ability of material to expand and contract.
Elliptical Arch
One of the strongest arches in brick masonry. It springs from a horizontal seat at and on the spring course, and the way its haunch crowns up adds to its strength.
Epoxy Mortar
Mortar of a thermosetting resins containing epoxy groups that are blended with other chemicals to form strong, hard chemically resistant mortar.
Expanded Shale, Clay and Slate
A ceramic lightweight aggregate prepared by expanding select minerals in a rotary kiln at temperatures over 1,000° (1,850° F).
Expanded Shale, Clay and Slate Institute (ESC
The international trade association for manufacturers of rotary kiln-produced expanded shale, expanded clay and expanded slate lightweight aggregate.
Expansion Joint
Vertical or horizontal joints used to separate masonry into segments to control cracking.
Extrude/Extrude Joints
To force clay through a die to give it shape - such as a brick. See Movement Joints.
Face
The exposed surface of a wall. Also the surface of a masonry unit to be exposed in finished work.
Ferrule
Metal band around the handle of the trowel at the shank end. Designed to protect the handle.
Fine Aggregate
Material that will almost entirely pass a No. 4 sieve, and be predominantly retained on the No. 200 sieve.
Flame Finish
The process of using a flame to pop off the surface of the stone face. This is performed only on granite and can be used both on interior and exterior stone.
Flashing
Sheet metal or plastic placed in mortar joints and air spaces in masonry for protection against water seepage.
Function & Code Requirements
Flashings are membranes that collect water that has penetrated the exterior wythe and direct it back to the exterior. Design cavity flashing above any horizontal element that will block the downward flow of water. The 2006 International Building Code requires flashing as follows: “Flashing shall be installed at the perimeters of exterior door and window assemblies, penetrations and terminations of exterior wall assemblies, exterior wall intersections with roofs, chimneys, porches, decks, balconies and similar projections and at built-up gutters and similar locations where moisture could enter the wall.”
Flashing Types
Flashing materials include but are not limited to sheet metal (copper, galvanized steel, stainless steel, aluminum, lead), EPDM (ethylene propylene diene monomer rubber), plastics and asphalt impregnated membranes. Self-adhesive membranes are popular with many masonry designers and provide adequate durability for many applications. Copper, stainless steel, and lead flashing are used in buildings where the designed service life is measured in hundreds of years.
Installation
Flashings must be installed in continuous runs with sufficient overlap and adhesive at joints to prevent moisture from migrating under the flashing.
Termination at Backup
Several methods are available for terminating the flashing at backup: 1) adhering to the back up with mastic or similar adhesive. 2) securing with a mechanically anchored termination bar. 3) inserting into a cut reglet in the back up wall. 4) wrapping through a mortar bed joint in the backup.
Termination at Exterior
As per the BIA (Brick Industry Association), the flashing should slope towards the exterior and extend beyond the face of the wall ½" to form a drip.
Flashing End Dams
End dams are used to terminate horizontal flashing runs to contain water on the flashing where it will be directed out of the wall system via weeps. Where the flashing is not continuous, such as over and under openings in the wall, the ends of the flashing should be extended beyond the jamb lines on both sides and should be turned up into the head joint several inches at each end to form a dam.
Flashing Laps, Flashing Corners
Flashing must be continuous to work properly. As flashing is not usually installed in continuous sheets, flashing should be lapped at least 6-in. and the laps sealed with a compatible adhesive. Fold flashing at corners or use prefabricated corner elements, sealed to the flashing at each side of the corner.
Flemish Bond
A bond consisting of headers and stretchers alternating in every course and laid so that they always break the joint.
Flemish Header
In a flemish bond, a header is placed in the middle of the stretchers in the courses above and below.
Flush Joint
See Movement Joints
Foundation Ledge
A foundation ledge provides a positive water barrier at the floor level.
Good construction practice recommends an integral foundation ledge a minimum of 3 inches below the level of the floor slab. A foundation ledge provides a positive water barrier at the floor level.
Furrowing
Small indentation cut into the mortar bed by a trowel to prepare the mortar bed for the brick.
Glazed Concrete Block
Ceramic or porcelainized glazes and/or mineral glazes used to face masonry units.
Gothic Arch
An arch with a rather high rise, with sides consisting of arcs of circles, the centers of which are at the level of the spring line. The Gothic arch is often referred to as a crop, equilateral, or lancet arch, depending upon whether the spacing of the centers are less than, equal to, or more than the clear span.
Grade
A predetermined percent of allowable imperfections for stone. Grades are used to create a scale to which stone can be sold and installed. Grade also limits the overall dimension that stone can be fabricated. The groups are granite-group A, marble-group B, marble-group C and marble-group D.
Granite
An igneous rock created deep within the earth. This rock is dense, difficult to create to final form, but is very durable.
Granular Insulation
A water-repellent or non-water absorbent fill material that pours readily into cores of masonry units or cavity type walls.
Grout
A cementitious component of highwater-cement ratio, permitting it to be poured into spaces within a masonry wall. Grout consists of Portland cement, lime and aggregate.
Grout is a highly fluid mixture of cementitious materials, aggregate, and water, used to solidly fill spaces around reinforcement and anchorage. Grout is required to be placed at a slump of 8 to 11 inches – a very wet mix – to flow into the grout space. Excess water in the mix does not adversely affect grout strength as it is absorbed by surrounding masonry. Masonry grout may be mixed on site or delivered in ready-mix trucks.
Benefits & Techniques
Grout is used to bond reinforcement to surrounding masonry, increase fire ratings and thermal mass, and improve sound dampening qualities.
ASTM Requirements for Grout
ASTM C476, Standard Specification for Grout for Masonry, lists grout requirements. All grout is to have a slump of between 8 and 11 inches, and a compressive strength exceeding 2,000 psi. Fine grout (sand aggregate only) may be used in all applications and is required when the grout space is small. Coarse grout contains aggregate up to 3/8” size and is an economical mix commonly used for reinforced masonry construction. See the Building Code Requirements and Specification for Masonry Structures Specification Table 7 for grout space requirements.
Common formulations for site-mixed grout are:
Fine Grout - 1 part cement to 3 parts sand (by volume)
Coarse Grout - 1 part cement, 3 parts sand, and 2 parts gravel
Placing Grout
Low lift grouting:
For low lift grouting, walls are built to 5 feet or less, and vertical reinforcement is then placed into hollow cells or reinforced cavities. Grout is placed in one continuous pour to the top of the wall and consolidated before building an additional 5 feet of masonry.
High lift grouting:
Walls may be built up to 24 feet tall, before grouting, when following the high-lift method. Cleanouts are left at the base of the wall at each bar position to facilitate inspection and also for removal of mortar debris from the base of each grouted cell. Cleanouts are formed by leaving out a masonry unit, a face shell, or part of a face shell. Following inspection, vertical reinforcement is installed, cleanout covers put in place and braced, and the wall grouted.
Grout lifts have historically been limited to 6 feet, meaning that grout is poured and consolidated in lifts of 6 feet or less until the full wall height is filled. Recent versions of the Building Code Requirements and Specification for Masonry Structures Specification (Section 3.5 D) now permit story-height grout pours of up to 12’-8” so long as the masonry is at least 4 hours old, the grout slump is between 10 and 11 inches, and there are no intermediate bond beams within the grout pour.
Consolidating Grout
Once placed in the wall, grout must be consolidated using mechanical vibrators whenever it is placed in lifts of more than 12 inches (see Building Code Requirements and Specification for Masonry Structures Spec 3.5). Grout is consolidated initially, during placement, for proper flow and to remove any entrapped air from the pour.
Water absorbed by surrounding masonry units causes freshly placed grout to shrink and grout is required to be re-consolidated to remove shrinkage cracks and arching voids. The time delay for reconsolidation varies, but usually grout should be reconsolidated 5 to 15 minutes after initial placement.
Self-Consolidating Grout
Self-consolidating grout (SCG) is a specially formulated product designed to completely fill grouted spaces in reinforced masonry construction. While somewhat more expensive than standard masonry grout, SCG speeds placement and, because no consolidation is required, can save costs by reducing grouting crew sizes. The 2008 Building Code Requirements and Specification for Masonry Structures code contains material and placement requirements for SCG.
Specifying Grout
Quality Assurance & Testing
The Building Code requires that grout proportions be monitored on the jobsite. For site-batched grout, the inspector should record the volumes of cement, sand, and gravel being added to the mixer. Quality assurance of ready-mix grout is accomplished by review of the supplier’s certificates. Testing for slump and compressive strength, though not required by Code, should follow the requirements of ASTM C1019 - 11.
Nondestructive methods such as ultrasonic velocity testing, impact echo, microwave radar, and infrared thermography are often used to inspect grout placement after the wall is grouted. These methods are able to locate voids and cracks in the grout, and identify if the grout is placed at the desired locations.
Hand Carts
Carts normally with two wheels which are used to manually handle or convey masonry units on the scaffold, building floors or around the project.
Head Joints
The vertical mortar joint between ends of masonry units. Often called cross joint.
Heel
Rear of the trowel blade.
Herringbone Pattern
A pattern of setting in which the units in a wall are laid aslant, instead of flat, with the direction of incline reversing in alternate courses, forming a zigzag effect. In floors of paving, the units are set at approximately a 45 degree angle with the boundary of the area being clad, alternate rows reversing direction to give a zigzag horizontal pattern, and the unit in one row filling the triangle between two units in the adjacent row.
High-lift Grouting
The technique of grouting masonry in lifts up to 12 feet.
Insulation
Material used to prevent the passage or leakage of heat, sound, etc. Comes in the form of board, granular fill or foam.
Function
The use of insulation reduces fluctuations in interior temperatures, moderating heat loss and gain.
Insulation Placement
Insulation can be placed variously in four positions:
- Exterior covered by a finish surface as with EIFS (Exterior Insulation Finishing System)
- In the cavity between the interior and exterior wythes
- Integral to the wall by placement in the masonry cores
- On the interior, such as batt insulation between studs or as rigid sheets anchored to the backup structure
Insulation Types
One popular and effective form of insulation is expanded polystyrene, sometimes referred to as rigid foam insulation. Fiberglass batt insulation is often used in single wythe stud wall construction and is placed between the studs. Perlite, Styrofoam beads or cellulose loose fill can be poured or blown into the masonry unit cores.
R-Values & U-Values
R-value is the thermal resistance to heat flow by a building assembly. A greater R-value offers greater insulation. U-value is the reciprocal of the R-value (U = 1/R) and defines transmission of heat through a building assembly. U is expressed as BTUs per hour per one square foot of area. A greater U-value offers less insulation.
Interlock
An arrangement by means of which the functioning of one part is controlled by the functioning of another.
Jack Arch
Flat arch usually used for short spans.
Jamb
Vertical sides of an opening such as the side of a door or window.
Joint Reinforcement
Joint reinforcement will not prevent shrinkage cracks from occurring but will help to limit the growth or widening of cracks.
Some type of horizontal reinforcement should be used with all concrete masonry construction to help control shrinkage cracks. Joint reinforcement will not prevent shrinkage cracks from occurring but will help to limit the growth or widening of cracks. One convenient way to include horizontal steel in CMU walls is to embed wire reinforcement in the mortar joints. In areas with high seismic design categories, the need for joint reinforcement is reduced or eliminated. The wall is constructed using bond beams that contain horizontal reinforcement. This type of construction is required to meet minimum seismic requirements but also assists in controlling shrinkage cracks.
Because brick expand rather than shrink, horizontal joint reinforcement is not used with clay masonry except in special situations where it is used to resist structural load. In certain seismic design categories single wire joint reinforcement is required in the construction of brick veneer.
Special seismic veneer ties hook into the wire.
Types & Sizes
Two types of joint reinforcement are produced: truss type (diagonal cross rods) and ladder type (straight cross rods). Ladder type is preferred as the straight cross rods are less likely to obstruct reinforcement and grout placement.
Joint reinforcement can be purchased with a wide range of rod diameters. No. 9-gauge side rods are typical; larger sizes may be specified if more steel area is needed to resist structural loads. Side rods need to be no larger than ½ the mortar joint width, or 3/16” diameter, for typical masonry construction.
What to Do at Expansion and Control Joints
All horizontal joint reinforcement should be cut at expansion and control joints. Do not run joint reinforcement through movement joints or stress concentrations, cracking, and spalling will occur.
Connections Between Wythes In Cavity and Composite Walls
Structural connection between wythes can be incorporated in the horizontal reinforcement. Side rods in ladder type reinforcement span the cavity to bond interior and exterior wythes. Pintle-type triangle ties can be used in conjunction with ladder type reinforcement, with channel slots cast into concrete slabs and with connections to stud construction.
Corrosion protection
The Building Code Requirements and Specification for Masonry Structures specification permits either hot-dipped galvanized or mill-galvanized corrosion protection for joint reinforcement. The 2006 International Building Code requires a hot-dipped galvanized coating for use in exterior walls and interior walls where the relative humidity will be 75% or more. The IBC permits mill-galvanized joint reinforcement for interior applications only.
Construction Concerns
Joint reinforcement is installed in the wall by first laying it on a bare concrete masonry course and then covering it with mortar. Mortar will fill in underneath the joint steel when the next block course is placed.
Joint reinforcement must also be placed to provide 5/8” mortar cover between the face of the side rod and the face of the masonry wall. This cover provides some degree of weather protection.
Journeyman
Craftsman or tradesman who has completed and passed an apprenticeship in a trade.
Kiln
Oven for firing brick or tile.
Ladder-type Wall Reinforcing
A type of horizontal wall reinforcement. A reinforcement system.
Lateral Force
Force placed on a structure by wind or earth pressure pushing laterally against a wall.
Level
A tool for determining, or adjusting a surface to an even horizontal plane.
Lift
Height of grout (or concrete) placed at one time from one pour.
Lightweight Aggregate
Aggregate of low density used to produce lightweight masonry, lightweight mortar, and lightweight grout, and includes expanded shale, clay, slate, and slag, pumice, volcanic cinders, scoria, tuff, and the end products of coal or coke combustion.
Limestone
Formed below water and compacted this is a highly concentrated crystalline calcium carbonate (calcite) but also contains silica, alumina, iron oxide and magnesia.
Formed below water and compacted this is a highly concentrated crystalline calcium carbonate (calcite) but also contains silica, alumina, iron oxide and magnesia.
Resources
Lintel
Horizontal structural unit (beam) over an opening; support member over a door or window opening.
Lintels are structural beams that carry loads over an opening such as a door, window, or HVAC penetration. Reinforced masonry lintels are usually the most convenient. Masonry lintels may be 1 or more courses tall, with horizontal reinforcement grouted in place. Use special lintel units (u-shaped, with a solid base) where the bottom of the lintel will be exposed in service. Loose steel lintels (angles, T-sections, wide-flange sections, or channels with base plates) may also be used to support masonry over an opening.
Reinforced CMU vs. Loose Steel Lintel
Reinforced masonry lintels are inherently fireproof and provide a uniform appearance once in place. Masonry lintels will have to be shored, however, until the grout has gained enough strength to resist applied loads. Steel lintels require no shoring, but can interfere with jamb steel in reinforced masonry construction where the lintel bears on each side of the opening. Steel lintels must be fire-proofed and have Building Code Requirements and Specification for Masonry Structures reported by the Masonry Standards Joint Committee (MSJC). Loose steel lintels are usually a better choice to support thin veneers; reinforced masonry lintels are often used in load-bearing walls.
Horizontal Reinforcement, Design Tables
Live Loads
A type of vertical force, forces applied by the contents and occupants of a building.
Low-lift Grout
Grout must be placed into the walls after walls reach a certain height. Building of walls may continue only after grout is in place.
Marble
A metamorphic rock formed from limestone. This stone consists primarily of calcite and dolomite. Marble is a stone formed all over the world.
Mason
One who builds or works with stone or brick.
Mason Contractors Association of America (MCA
The national trade association representing masonry contractors and suppliers in national legislative and political affairs, codes and standards composition, workforce development, education, market promotion and general industry advocacy.
Masonry
That which is built by a mason; anything constructed of the materials used by masons, such as stone, brick, tiles, or the like.
Masonry Institute of America (MIA)
A promotion, technical and research organization established to improve and extend the use of masonry.
Masonry Standards Joint Committee (MSJC)
An organization composed of volunteers who through background, use, and education have acquired experience in the manufacture of masonry, or in the design and construction of masonry structures.
Miter
A joint formed by fitting together two pieces beveled to a specific angle (usually 45 degrees) to form a corner.
Monolithic
Without joints.
Mortar
Mortar performs many functions: it fills gaps between units, bonds the units together, provides weather protection.
ASTM Requirements for Mortar
Mortar performs many functions: it fills gaps between units, bonds the units together, provides weather protection. Simply changing mortar color or joint tooling provides opportunities for varying architectural treatments. Mortar specifications contained in ASTM C 270, Standard Specification for Mortar for Unit Masonry, spell out material requirements and typical formulations.
Mortar Types: by Proportion, by Property
Mortar types are designated by letter as Types M, S, N, O, and K (every other letter in the word MaSoNwOrK). ASTM C 270 contains two alternative specifications of masonry mortars, property or proportion. Mortar can specified by only one of these methods, not both. Under the proportion specification the type of mortar is created using volumetric proportions of cementitious materials and aggregates as set forth in Table 1 of ASTM C 270. No physical requirements are required of the mortar with this method. The property specification requires pretesting of the mortar mix designs in the laboratory to establish compliance with Table 2 of ASTM C 270. The mortar produced using the property specification must meet the required properties of compressive strength, water retention and air content. Factory blended mortar generally is manufactured to meet the property requirements of ASTM C 270.
Mortar Usage
A wide range of mortar types are available for use, depending on durability requirements, unit types, and the initial rate of absorption (suction) of masonry units. Mortars with a high cement content (Type M and S, for example) are very strong but are not as “workable” as mortar with a lower cement content (Type N or O). A good rule of thumb is to not use excessively strong mortars, with a high cement content, as these mortars are less able to retain water and can be prone to shrinkage cracking. Type S and N mortars are commonly used for veneer and structural applications, although Type N mortar is prohibited in the higher seismic design categories.
- Choosing the Right Mortar for the Job
Mortar Joint Filling
Typical mortar joint thickness is 3/8” for most applications. Mortar joints must be completely filled to resist water penetration and for proper bond. When building with solid units, mortar must completely fill all bed (horizontal) and head (vertical) joints.
For hollow masonry units used in reinforced masonry construction, bed joint mortar is placed only on the face shells. Head joints are filled at each wall face, to a depth equal to the face shell thickness. The exception to this is at columns and pilasters, where all face shells and cross webs are typically filled to resist structural loads. The bed joint at the starting course on the foundation also needs to be solidly filled. The Building Code Requirements and Specification for Masonry Structures Specification (Section 3.3 B. 1) requires the starting bed joint to be between ¼ and ¾ inch thick.
In multi-wythe construction, collar joints (less than 1” wide) or reinforced spaces should be completely filled with grout. Drainage cavities, on the other hand, should be free and clear of mortar obstructions that inhibit water drainage.
Pigmented Mortar
Adding pigments to mortar gives the architect an opportunity to change the wall’s appearance with little extra effort. Pigmented mortars are more expensive and can be tricky to batch, place, and tool to get a consistent color throughout. Small variations in mortar color will normally fade after final cleaning or with several months’ weather exposure.
Mortar Joint Profiles
The final act of laying mortar is tooling, with a metal sled or runner, after the mortar is fairly hard (often called “thumbprint hard”). Joint tooling compresses the surface of the joint and brings cement fines to the surface to provide a durable weather surface free of cracks or delaminations. Concave tooled joints are most resistant to weather penetration. Raked or struck joints are sometimes used to create shadow lines for architectural effect, but this practice creates ledges where rain and snow collect, often leading to staining or increased water penetration.
Specifying Mortar
Mortar Quality Assurance & Testing
Movement Joints
Movement joints are used to allow dimensional changes in masonry and to minimize random wall cracks and other distress.
Movement joints are used to allow dimensional changes in masonry and to minimize random wall cracks and other distress. There are various types of movement joints in buildings: expansion joints, control joints, building expansion joints and construction joints. Each type of movement joint is designed to perform a specific task and should not be used interchangeably.
An expansion joint is used to separate brick masonry into segments to prevent cracking due to changes in temperature, moisture expansion, elastic deformation due to loads, and creep. Expansion joints may be horizontal or vertical. The joints are formed of highly elastic materials placed in a continuous, unobstructed opening through the brick wythe – brick expansion joints must be free and clear of all obstructions (such as mortar) to function properly. This allows the joints to close as a result of an increase in size of the brickwork. Expansion joints must be located so that the structural integrity of the brick masonry is not compromised.
A control joint is used in concrete or concrete masonry to create a plane of weakness which, used in conjunction with reinforcement or joint reinforcement, controls the location of cracks due to volume changes resulting from shrinkage and creep. A control joint is usually a vertical opening through the concrete masonry wythe and may be formed of inelastic materials. A control joint will open rather than close. Control joints must be located so that the structural integrity of the concrete masonry is not affected.
A building expansion (isolation) joint is used to separate a building into discrete sections so that stresses developed in one section will not affect the integrity of the entire structure. The isolation joint is a through-the-building joint.
A construction joint (cold joint) is used primarily in concrete construction where construction work is interrupted. Construction joints are located where they will least impair the strength of the structures.
National Concrete Masonry Association (NCMA)
Offers a variety of technical services and design aids through publications, computer programs, slide presentations and technical training.
Normal Weight Aggregate
Material such as sand, gravel, slag, crushed stone, etc.
Occupational Safety and Health Administration
A department of the U.S. Department of Labor to promulgate health and safety in the U.S. Establishes regulations and enforces such.
Parabolic Arch
The strongest of all arches. It has a gradual oval shape.
Parapet Flashing
It is important to install flashing at the parapet in two key locations: 1) under the coping stone, and 2) at the roof line.
Function
It is important to install flashing at the parapet in two key locations: 1) under the coping stone, and 2) at the roof line. Installation of flashing under the coping stone prevents water infiltration at joints in the coping stone. Installation of flashing at the roof line can prevent warm moist air from the lower wall filling the parapet cavity. The parapet will go through more freeze-thaw cycles than lower walls as parapets are exposed on both sides. Particularly in cold climates, the moist air in the parapet will cause significant freeze-thaw damage.
Parapet Flashing Types
Flashing materials include sheet metal (copper, galvanized steel, stainless steel, aluminum, lead), EPDM (ethylene propylene diene monomer rubber), plastics and asphalt impregnated membranes. Self-adhesive membranes are popular with many masonry designers and provide adequate durability for many applications. Copper, stainless steel, and lead flashing are used in buildings where the designed service life is measured in hundreds of years.
Parging
Process of applying a coat of mortar to masonry construction, especially used for masonry walls. Also, the cement mortar coat itself.
Pier
A short masonry or concrete column supporting the foundations of the floor structure in spaces without a basement. Pier may be freestanding or bonded at its sides to other masonry or concrete. A masonry column used to support a garden wall. A freestanding column.
Pilaster
A pier or column forming part of a masonry or concrete wall, partially projecting from it and bonded to it. Designed to receive joist or beam load.
Plaster
Used in interior stone installations to adhere the anchors in place as well as to fill butt jointed stone.
Plastics
Refractory brick in a plastic-like moldable consistency.
Plumb
Exactly vertical. Measured with a plumb line.
Point
Tip of the trowel blade.
Polish
A mechanical method creating a glossy smooth finish on stone. Generally marbles and granites can be polished to expose the full grain and color of the piece.
Polystrence
A tough, clear, colorless plastic material.
Porous
Materials ability to absorb water having many small openings.
Portland Cement
Fine, grayish powder formed by burning limestone, clay or shale and then griding the resulting clinkers. The result is a cement which hardens under water and which is used as a base for all mortar. Portland cement is a grade of cement, not a brand.
Portland Cement Association (PCA)
The Portland Cement Association represents cement companies in the United States and Canada through market development, engineering, research, education and public affairs programs.
Prism
A small assemblage made with masonry units and mortar and sometimes grout. Primarily used to predict the strength of full scale masonry members.
Puddling
The process of settling or consolidating grout in a masonry reinforced wall to prevent the formation of voids.
Quarry Sap
The water present in block stone when removed from the ground. Quarry sap seasons out anywhere from sixty days to eight months, depending on the type of stone.
Quoin
Large squared stone or brick set at the corner formed by two masonry walls. Projects out from the corner in some cases.
Racked Joint
See Movement Joints
Racking
Laying or stepping back each higher masonry course.
Rebar
Horizontal or vertical reinforcing bars used to reinforce a masonry structure.
Refractory
Any non-metal material or object that can withstand high temperature without becoming soft.
Reinforcing
To strengthen a structure by the addition of something to that structure.
Rock
A wide variety of natural minerals found in virgin form on or below the surface of the earth.
Roman Arch
A semicircular arch. If built of stone, all units are wedge-shaped.
S-Jointer
A shorter jointer used for head joints.
Safety Data Sheets (SDS)
Documents describing the known hazards associated with a material.
Sample Panel
A test panel designed to 1) demonstrate the quality of materials and the kind of workmanship that will be used through-out the construction period or 2) be observed throughout construction of the job for any change or damage as a result of changes in weather conditions.
Sandstone
Generally quartz based, cemented together with a high percent of silica, sandstone also contains calcium, carbonate and iron compounds, this stone generally is formed without sediment grains.
Sealant
Silicone, polyurethane or polysulphate based chemicals with elastomeric (elastic) characteristics used at various conditions in stone joints.
Segmental Arch
Similar to semi-circle arch. Segment of a circle.
Semi-Circle Arch
See Roman Arch
Shank
Connect the trowel blade to the trowel handle.
Silica
A white or colorless compound (SiO2) occurring as quartz, sand, flint, agate, and many other minerals.
Sill
Bottom of a window or door frame. Skew. To twist back or lean; to incline. Shoring Jacks. Support masonry lintels.
Sled Runner (Boot Rod)
A longer jointer with a wood handle used for bed joints.
Soft Mud Process
A brick manufacturing process using a soft brick soffit.
Span
Distance between two supports.
Spring Line
For minor arches, the line where the skewback cuts the soffit. For major parabolic arches, the term commonly refers to the intersection of the arch axis with the skewback.
Stiff Mud Process
A process through which bricks are made.
Stinger
A long cable that powers the mechanical vibrator used to consolidate grout.
Stone
Term used to discuss rock in a semi or finished form to be used in constructions or landscaping.
Stone Veneer
Stone veneer simulates full depth, load-bearing stone construction.
Stone veneer simulates full depth, load-bearing stone construction. The veneer configuration allows installation of water proof membranes, flashings and insulation behind the stone, which otherwise would not be possible.
Stone Types
The type of stone used will be determined by cost, availability, appearance, durability and ease of fabrication (related to cost). Granite, for example, is a much harder stone and therefore more difficult to shape and fabricate than limestone or sandstone, which will affect cost in terms of labor.
Many types of prefabricated or cast stone are available that simulate real stone but are fabricated in modular or near modular sizes and shapes to expedite construction. Manufactured stone will generally be less durable both because the material is typically less dense and because the units may not be as deep, so that the veneer will not be as massive and therefore stable.
Stone Veneer Installation Patterns
Stone veneer can be installed in various patterns. Ashlar patterns are composed of rectangular units having sawed or squared bed surfaces and bonded by mortar. Rubble patterns are composed of irregular-shaped units bonded by mortar.
Stone Anchorage, Code Requirements
Codes covering anchored and adhered stone veneers are covered under the same section as those for manufactured modular masonry and specified in chapter 6 of the Building Code Requirements and Specification for Masonry Structures reported by the Masonry Standards Joint Committee (MSJC).
Construction Issues
The non-modular and uneven characteristics of natural stone create challenges for the installer including uneven coursing and differing unit depths. Uneven bedding surfaces must be compensated for with varying thicknesses of mortar application. Natural cleavage lines can result in cracking or fracture of stone units.
Links Related To Building Stone
Struck Joint
See Movement Joints
Structural Backup
The structural backup of the building system is designed to support floor and roof loads and to resist lateral wind loads and seismic movement.
The structural backup of the building system is designed to support floor and roof loads and to resist lateral wind loads and seismic movement. The exterior veneer is not structural and is connected to the structural backup via wall ties and transfers some wind load to the backup.
Backup Types
Concrete masonry/Concrete block: Concrete Masonry Unit (CMU) walls are constructed with vertical steel reinforcement bars grouted in the CMU cells. The spacing and size of the bars is dependent on the structural performance requirements of the wall.
Brick masonry: Unreinforced solid brick masonry, 2 wythes or greater, can function as structural backup, although this is a rare construction type. Reinforced brick masonry as structural backup requires a minimum brick size to allow insertion of steel reinforcement and grout.
Reinforced concrete: The connection of the veneer to reinforced concrete can be achieved by veneer ties anchored to the concrete or by a dovetail tie and slot system cast integrally into the concrete wall.
Steel Stud: Steel stud construction is used in conjunction with structural steel or reinforced masonry and is not structural backup itself. Veneer anchors are secured to the backup wall through flashings, water resistive barriers and sheathing directly into steel studs.
Wood Stud: Veneer anchors are secured to the backup wall through flashings, water resistive barriers and sheathing directly into wooden studs.
Performance: Structural, Energy, Sound, Fire
Structural Clay Tile
Hollow masonry building units composed of burned clay, shale, fire clay or mixtures thereof.
Substrate
Tensile strength forces that separate the masonry unit from mortar.
Terra Cotta
A hard semifired waterproof ceramic clay used in pottery and building construction.
The Masonry Society (TMS)
An international gathering of people interested in the art and science of masonry.
Toothing
Temporary wall end where alternate stretchers project out. Projecting masonry units are called tooths.
Trowel
A flat-bladed hand tool for leveling, spreading, or shaping substances such as cement or mortar.
Truss-Type Wall Reinforcing
A type of horizontal reinforcing systems made with diagonal cross rods through wall flashing.
Tutor Arch
A pointed, four-centered arch of medium rise-to-span ratio.
Vapor Retarder
Vapor retarders minimize the movement of moisture from the interior of the building into the cavity wall where condensation can degrade insulation and structural members.
Function & Code Requirements
Vapor retarders minimize the movement of moisture from the interior of the building into the cavity wall where condensation can degrade insulation and structural members. As per R318.1 2006 IRC (International Residential Code), “In all framed walls, floors and roof ceilings comprising elements of the building thermal envelope, a vapor retarder shall be installed on the warm-in-winter side of the insulation.
Exceptions:
- In construction where moisture or freezing will not damage the materials.
- Where the framed cavity or space is ventilated to allow moisture to escape.
- In counties identified as in climate zones 1 through 4 in Table N1101.2.” Vapor retarders, while required by the 2003 International Building Code, are not mentioned in the 2006 International Building Code.
Continuous vapor barriers to reduce the passage of water vapor into the wall generally are used only when insulation is placed on the inside face of the wall. The relatively small amount of moisture that does get into the wall from the inside of the building will diffuse provided that the exterior surface is “breathable.”
Vee Joints
See Movement Joints
Veneer Lintels, Shelf Angles
Lintels provide support of brickwork over masonry openings and are supported by bearing on masonry at the jambs on either side of the opening.
Function & Code Requirements
Lintels provide support of brickwork over masonry openings and are supported by bearing on masonry at the jambs on either side of the opening. Shelf angles are typically installed at each floor and support the weight of the brickwork for that story. As per 6.2.2.3.1 of the 2006 Building Code Requirements and Specification for Masonry Structures ( reported by the Masonry Standards Joint Committee (MSJC) structures with a maximum veneer height of 30 ft from foundation to top of wall and 38 ft from foundation to top of gable can have their entire brick veneer supported directly on a foundation wall, footing or non-combustible support without shelf angles. Brick above these limits must be supported by shelf angles at each floor.
Sizing
Lintels and shelf angles must be sized by an engineer to meet the strength requirements of the steel design code. Lintels and shelf angles are also sized to be very stiff to minimize masonry cracks. Design codes call for a maximum deflection between support points of L/600 or 0.3" and rotation of less than 1/16". The horizontal leg of all angles should be sized to support a minimum of 2/3 the thickness of the veneer wythe.
Corrosion Protection
For severe climates and exposures, consideration should be given to the use of galvanized or stainless steel shelf angles. At a minimum, steel angles should be shop primed with a corrosion inhibitive coating and repainted if the steel will be welded. Even where these materials are used, continuous flashing should be installed to cover the angle.
Anchorage to Backup
Lipping Brick at Shelf Angles
In order to conceal the front edge of the steel lintel, a common practice is to lip the brick so that the front face extends over the steel angle.
Veneer Ties
Used to anchor veneer to walls - comes in many styles or types.
A wide variety of veneer ties are available from various manufacturers. The purpose of the veneer tie, regardless of design or type, is to transfer loads from the veneer to the backup structure. Veneer ties are designed to resist compressive and tensile loads that arise from lateral loads such as from wind or seismic excitation. Some tie systems are adjustable, to accommodate construction tolerances or permit the veneer to expand and contract independently of the backup structure.
Code Requirements
The Masonry Standards Joint Committee (MSJC) defines code requirements for masonry structures.
Installation & Anchorage
Embed wall tie ends at least ½" in the outer face shell of hollow units. Embed wall ties at least 1 ½" into the mortar bed of solid masonry units or solid-grouted hollow units. Maximum spacing between ties (according to the Building Code Requirements and Specification for Masonry Structures reported by the MSJC) is 36" horizontally and 24" vertically.
Corrosion Protection
Building Code Requirements and Specification for Masonry Structures Section 2.4 F lists required corrosion protection for steel joint reinforcement, ties, and anchors. Unless otherwise required, protect carbon steel ties from corrosion by galvanizing or epoxy coating. Specific minimums are outlined in the above referenced section.
Vertical Force
See dead or live loads.
Vertical Reinforcement
Vertical reinforcement is used in masonry walls to resist tensile stresses that may arise from flexural and shear loads.
Vertical reinforcement is used in masonry walls to resist tensile stresses that may arise from flexural and shear loads. Masonry columns and pilasters are also reinforced vertically to increase resistance to axial loads.
Types & Sizes
Deformed reinforcing bars (rebar) should conform to ASTM A 615. Grade 60 reinforcement with a yield strength of 60,000 psi is most common; in some markets Grade 40 (yield strength of 40,000 psi) may also be available.
The Building Code Requirements and Specification for Masonry Structures reported by the Masonry Standards Joint Committee (MSJC) permits reinforcement sizes up to #11 (1 3/8” diameter) to be used in masonry construction, but it is rare to see bars larger than #8 (1” diameter). When masonry is designed using the Strength Design provisions (Building Code Requirements and Specification for Masonry Structures Chapter 3) the maximum bar size is limited to the lesser of #9 bars, 1/8 times the nominal wall thickness, or ¼ of the clear dimension of the cell, course, or collar joint being reinforced. The total reinforcement area placed in a cell may not exceed 4 percent of the cell area (8% at lap splice locations). For 8-inch masonry units, the cell area is approximately 32 square inches, into which a maximum of 1.3 square inches of reinforcement may be placed.
How Installed
Vertical reinforcement is typically placed by dropping the bar into empty cells after the wall is built. It is good construction practice to have vertical reinforcement in place before grouting. The Building Code Requirements and Specification for Masonry Structures requires reinforcement to be in place prior to grouting (See Building Code Requirements and Specification for Masonry Structures Section 3.2 E). The practice of stabbing bars into freshly placed grout is not permitted as it does not permit the inspector to verify proper reinforcement placement.
Another option is to use open-end “A” or “H” block units. These units have one or both end webs removed, and can be placed around vertical reinforcement projecting up from the foundation or the previous grout pour.
Keeping Cells Clean
Special care needs to be taken when building reinforced masonry walls to prevent excessive amounts of debris, mortar droppings, etc., from falling into the reinforced cell. Small amounts of mortar and debris are acceptable so long as grout bond is not severely inhibited. Mortar protruding more than ½” into the grouted cell must be removed before grouting (Building Code Requirements and Specification for Masonry Structures Spec. 3.3 B. c.) so it does not inhibit grout flow.
Lap Splices
Lap splices are used to ensure reinforcement continuity up the height of the wall. A length of reinforcement is left protruding up from the top of every grout pour, to lap with the reinforcement in the next grout pour. Tensile stresses are transferred from one bar to the next through bond with the surrounding grout. It is not necessary for bars to be in contact with one another at lap splices and the Building Code Requirements and Specification for Masonry Structures permits adjacent bars to be separated by up to 8” for non-contact lap splices.
The length of overlap is designed by the engineer, but will vary depending on the masonry strength and bar diameter. Longer laps are also required for bars placed close to the wall face.
Bar Positioners
Bar positioners can take many forms but are often periodically embedded in mortar joints up the height of the wall. After the wall is built, reinforcement is fed down through the positioner to ensure the bar is held in the required location.
Older building codes required bars to be held in place by positioners during grouting. The current Building Code Requirements and Specification for Masonry Structures does not explicitly require bar positioners, but it is the contractor’s responsibility to “support and fasten reinforcement together to prevent displacement” during grouting (Section 3.4 B).
Placement Tolerances
Reinforcement placement is critical for ensuring the wall has enough strength to resist design loads. Misplacing bars by as little as ½” can have a serious effect on the wall’s ability to resist loads.
Reinforcement placement tolerances are listed in the Building Code Requirements and Specification for Masonry Structures Section 3.4 B 7. Tight tolerances are required: bars must be placed within ±½” of the specified location for most designs (d distance 8” or less). Placement along the length of the wall is required to be within ±2” of the specified spacing.
Clearance
Reinforcement placement needs to be designed to ensure there is enough space around the bar for proper grout flow. A minimum space of either ¼” (for fine grout) or ½” (for coarse grout) must be left between adjacent bars and any masonry surface. Bars are permitted to be in contact with one another at lap splices.
Protection
Masonry reinforcement is embedded deep in walls and protected from exterior weather by the masonry unit face shell and a layer of grout. No special corrosion protection is used for masonry construction. Epoxy-coated, galvanized, or stainless steel reinforcement may sometimes be used in severe environments such as seawalls, chemical plants, and some food processing facilities.
Cost Effective Design & Spacing
Voussoir
One of the wedge-shaped masonry units which form the arch ring. An example is a brick in a jack arch.
Wall Caps
Wall caps and flashing directly beneath the cap must be impervious to moisture penetration.
Function
The tops of masonry walls are often the most vulnerable to moisture infiltration, and special care must be taken to design and install a proper wall cap. Wall caps and flashing directly beneath the cap must be impervious to moisture penetration.
Wall Cap Types
Types of parapet caps include stone, cast stone, clay brick masonry, concrete masonry, and formed sheet metal. Parapet caps should slope in towards the roof. All parapet caps (except for sheet metal coping) should incorporate through-wall flashing directly beneath the cap to prevent moisture from saturating the wall beneath. Joints between wall cap elements are often finished with a flexible sealant.
Anchorage
Most situations require stone or masonry wall caps to be anchored to the wall below. Without anchors, wall caps will loosen as the wall below responds to temperature and moisture variations. Anchors are also required to satisfy prescriptive requirements for seismic design, which state that: “component seismic attachments shall be bolted, welded, or otherwise positively fastened without consideration of frictional resistance produced by the effects of gravity” (ASCE (American Society of Civil Engineers) 7-05, Section 9.6.1.2). Anchors may be installed into blind holes in the bottom of coping segments or in mortar joints between units.
Water-Resistive Barrier
Water resistive barriers are required over stud wall construction.
Function & Code Requirements
Water resistive barriers are not required over concrete or masonry walls. Water resistive barriers are required over stud wall construction. As per 6.1.5.1 of the 2006 Building Code Requirements and Specification for Masonry Structures ( reported by the Masonry Standards Joint Committee (MSJC) “design and detail the backing system of exterior veneer to resist water penetration. Exterior sheathing shall be covered with a water-resistant membrane, unless the sheathing is water resistant and the joints are sealed.” Chapter 1404.2 of the 2006 International Building Code requires that a minimum of one layer of No.15 asphalt felt or other approved material shall be attached to the studs or sheathing so as to provide a continuous water resistive barrier behind the exterior wall veneer. Felt paper is commonly applied over exterior sheathing on wood or metal stud construction.
The International Building Code and International Residential Code typically requires that subgrade walls be dampproofed for conditions where hydrostatic pressure will not occur, and waterproofed where hydrostatic pressures may exist. Waterproofing systems include but are not limited to 2- or 3-ply hot-mopped felts, 50 mil rubberized asphalt, 40 mil polyurethane rubber, 20 mil vulcanized rubber, and 20 mil thermoplastic sheets. The barrier is part of a comprehensive system, which includes proper wall construction and the installation of drains, gutters, and proper grading.
Weathered Joint
See Movement Joints
Weeps
Openings placed in mortar joints of facing material at the level of flashing, to permit the escape of moisture.
Function & Code Requirements
Weepholes are used to drain any water collected by the flashing. The 2006 International Building Code requires that weepholes provided on the outside wythe of masonry walls shall be at a maximum spacing on 33" and that they not be less than 3/16" in diameter. The BIA (Brick Industry Association) recommends that weepholes be spaced a maximum of 24", 16" when rope wicks are used, and that they be not less than ¼’ in diameter.
Weephole Types
Weephole types include but are not limited to plastic tubing, cotton rope wicks, rectangular vents installed at head joints and corrugated or fibrous mat placed at the bed joint. In addition, the head joint at the base of the wall can be left open. Plastic tube weep holes are not recommended as they can easily become clogged and lose effectiveness. The method that we prefer is a corrugated or fibrous mat on which the bottom course of the brick rests. This method provides a clear path for water to escape, generally free from the danger of being clogged by mortar droppings.
Installation
Many manufacturers are producing base flashing systems with integral weeps that incorporate fibrous or corrugated mat on which the base course of masonry rests. These take the guesswork out of installation and provide an effective weep system. Often, plastic weep tubes are inserted after the mortar is laid up, and the end result is that the weep tube is clogged before the wall is even complete. While we do not recommend weep tubes, if they are installed, they should be installed before the mortar is placed.
Wet Saw
A wet cutting diamond blade. Used on a saw that has a continual water pump supply on the blade keeping the blade clean and cool.
Winning
The process used to mine raw materials used for manufacturing brick.
Wythe
Vertical wall or tier of masonry units one-unit thick. The thickness of masonry separating flues in a chimney. Also called a withe or tier.
Z-Ties
A wall tie made with a 90 degree angle and a 2-inch leg on each side.