proper use of masonry joint reinforcement and accessories · 2016-09-09 · masonry joint...

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Proper Use of Masonry Joint Reinforcement and Accessories

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Proper Use of Masonry Joint Reinforcement and Accessories

Wire-Bond400 Rountree RoadCharlotte, NC 28217

Ensuring proper use of methods and materials allows masonry walls to perform well and enjoy a long life. Use of masonry joint reinforcement and accessories is an essential part of this. This course provides a brief history of solid masonry walls leading up to the modern cavity walls of today, including a discussion of the basic working knowledge of masonry joint reinforcing, structural codes, and moisture control in cavity wall construction.

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Purpose and Learning Objectives

Purpose: Ensuring proper use of methods and materials allows masonry walls to perform well and enjoy a long life. Use of masonry joint reinforcement and accessories is an essential part of this. This course provides a brief history of solid masonry walls leading up to the modern cavity walls of today, including a discussion of the basic working knowledge of masonry joint reinforcing, structural codes, and moisture control in cavity wall construction.

Learning Objectives:

At the end of this program, participants will be able to:

• describe the basic history of solid masonry walls evolving into today’s cavity walls• describe the types of joint reinforcing, their design, and installation in masonry wall construction• define the types of adjustable ties and stone anchors, their use, and installation, and• explain the types of flashing, mortar dropping collection devices, and weeps used in masonry walls.




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Table of Contents

A History of Masonry Walls 7

Developing the Masonry Structures Code 24

Joint Reinforcing for Single-wythe Walls 29

Joint Reinforcing for Multi-wythe Walls 37

Flashings, Mortar Dropping Collection 57Devices, and Weeps

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A History of Masonry Walls




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A Brief History of Masonry Walls

No one knows exactly when the first wall was built; perhaps cavemen and cavewomen felt they needed to protect themselves from wind, rain, and various animals that might try to get into their caves. Stone or dry mud from a lakebed would have been stacked to create some type of wall.

Although somewhat effective, these walls still required mud as a mortar to help support the stones or pieces of dry mud from a lakebed as the wall grew in height.

As time went on, people found that the mud alone was not sufficient as the water evaporated from the mixture. The mud would crack and fall out. In an effort to reinforce the mud/mortar, various grasses, weeds, and even horsehair was added to the mix. This mix was also used as “chinking,” the reinforced material placed between the logs of a log cabin that helps keep the wind, rain, and cold outside.




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Mesopotamia

6,000 years ago the Mesopotamians built the world’s first walled cities.

These walls used clay masonry units of special shapes and a running bond pattern. A running bond pattern is where the next row of bricks lays across the two ends of the bricks below. This pattern helped strengthen the wall from horizontal wind loads and is still the most common pattern used today.

It should be noted that as the wall grew in height, the wall’s overall thickness also grew in an effort to carry the loads from above.




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Pyramids of Giza

5,000 years ago the great pyramids were built from large blocks of stone that were set using white ground up rock with water added as its mortar.

This white rock was gypsum, which is still utilized today as a fire-rated core for gypsum board.




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Mud Brick

Eventually, builders decided that they needed a more uniform shape in creating their mud brick. So they created a wood form in which they added not only the mud and local silt, but also helped reinforce the bricks by using weeds, grasses, or even horsehair.

We still reinforce our masonry structures today with additives like chopped glass fiber, ceramic fiber, and wire welded mesh in things like concrete slabs and sidewalks. These wood-formed and sun-baked masonry units are still done in some areas around the world.




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Early Masonry Walls

The Monadnock Building in Chicago, Illinois was completed in 1891. With its 17-story load-bearing masonry walls, it was the tallest of any commercial structure in the world. Walls at the bottom of the structure were 6′ thick, tapering to 18″ at the top of the building.

The architect used an interior frame of cast and wrought iron to help support the walls from high wind loads. This was the first attempt at wind bracing. This building is often referred to as the “last masonry skyscraper.” Now all high-rise buildings use structural steel backup to help with lateral wind loads and minimize weight.

Images: courtesy of The Chicago Historical Society




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Wind-driven Rain

One of the biggest problems with solid masonry construction is how you might deal with water migration through the material. Wind and rain most often go hand in hand. Wind can push the water through the masonry and mortar used to set the units.

It should be noted that masonry does a great job at absorbing and storing heat, then slowly releasing that heat keeping heating, ventilating, and air conditioning systems from working too hard.

Wind-driven rain caused a lot of problems for early solid masonry walls.




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Early English Cavity Wall

In England in the late 1800s, solid masonry walls were still the norm. However, the problems typically associated with this type of structure were mildew and cold surfaces on the interior walls. In an effort to stop moisture and thermal migration, a cavity was created between the two wythes. Remember a wythe is a single unit of masonry. Special elongated bricks were created to bond the two wythes together creating a cavity. Its intent was to minimize the potential for a thermal break between the two wythes and minimize the surface area where water might push through to the interior wall.

This special bonding brick created a “masonry bond,” but this type of bonding still created a moisture path and thermal bridge between the two wythes. In an effort to address this problem, smaller wire ties were created to tie the two wythes together. These metal ties had a much smaller surface area reducing the thermal transfer. A bend, or “drip,” was added to the wire tie so that if water tried to migrate across the wire tie from the outside wall to the inner wythe, then it would drip down and be “weeped” away through small holes at the base of the wall back outside. This type of system was known as a “wire bond.”

Special bonding brick used to bond two wythes is called a masonry bond.

Interior plaster finish

This masonry bond created a moisture path and a thermal bridge. This masonry bond soon became a wire bond as metal ties were developed.




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Wall Ties in the 1800s

Old wall ties from the 1800s had drips or bends built into their design. These drips were there to help stop potential water from “walking” across the cavity to the interior wythe. The drip allowed water to drop down into the cavity and then be weeped away with periodic holes, or “weeps”, built into the bottom exterior wythe. It has been found that these bends can reduce the strength of the tie by as much as 50%. You will not find them in wire ties today.




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Brick Alternative

In the late 1800s, a stronger alternative was created to replace the interior brick wythe. In many instances, the exterior brick is considered a curtain wall or brick veneer. The interior wythe is normally there to carry the loads from above (wall, floor, roof, etc.). A single wythe of brick was limited in its structural ability.

The first concrete masonry unit (CMU) was molded in 1882. Concrete blocks create structures that are economical, energy efficient, fire-resistant, and involve minimal maintenance.

The first size was 7⅝″ wide x 7⅝″ high x 15⅝″ long; the same CMU dimensions are used today. The standard mortar joints for a typical CMU is ⅜″ thick. This brought the overall size of the CMU to 8″ x 8″ x 16″. A typical brick dimension is 3⅝″ wide x 2¼″ high x 7⅝″ long. Therefore, three bricks high plus three mortar joints equal 8″, allowing the brick to course out with the CMU.




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Concrete Exterior

Concrete blocks can be used as a finished exterior surface or as a structural backup wall for brick or stone veneers.

CMU can also have a ceramic coating applied to the outside face. This is a good choice for some very dramatic effects and it is easy to clean should graffiti become a problem.




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Today’s Block Backup Cavity Wall

All of this development has now led up to today’s block backup cavity wall as you see in the image. Managing potential water intrusion and loads, both vertical from material weight and horizontal from wind loads, is now addressed in this modern cavity wall.

After the slab or footing is poured, it is time to lay the CMU. The structural engineer may have called for reinforcing steel bars or “rebar” to be grouted into some of the CMU cells. Typically, this will be one or two pieces of rebar grouted solidly into the cell to help with wind loading in the area. The rebar will normally be centered in the cell so it can work equally with either positive or negative wind loads. Rebar positioners are used about every 4′ vertically. As you will see later in the course, some rebar positioners are better than others.




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As the CMU is laid, masonry joint reinforcing is also laid every other course or 16″ on center vertically. Since 99% of the projects specified call for ⅜″ mortar joints, it is important to remember that code dictates the masonry joint reinforcing not exceed half the thickness of the joint. Therefore, a ⅜″ mortar joint would require a 3/16″ maximum height for the masonry joint reinforcing. This allows for better coverage of mortar around the masonry joint reinforcing. The masonry joint reinforcing can be either 9 gauge (0.1483″) or 3/16″ diameter if more stringent loads are to be met.

Most CMU is 17⅝″ long with a center web. With a single ⅜″ mortared head joint, this brings the total length to 16″. If a brick or stone veneer is to be used, then the “tie” will occur at 16″ on center at the center line or web of the CMU. This brings the typical spacing for the ties to the exterior brick veneer to 16″ vertical and 16″ horizontal.

Code also states that any metal passing through the cavity of the wall shall be a minimum of 3/16″ in diameter. The “cavity” is the distance from the back of the CMU to the back of the brick. Insulation and air space can take up some of this space, but the cavity is still wythe to wythe.




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Masonry walls need movement joints to allow for either expansion or contraction in the wall. As a rule, brick tends to expand while CMU tends to contract. Since brick is exposed to the elements, ⅜″ expansion joints made of closed cell neoprene and allowing for a compression of 50% is normally used. Sealant or caulking is used to cover and protect the expansion joint from water and ultraviolet deterioration.

For CMU, a control joint is installed allowing for the CMU to contract. The block manufacturers will form blocks with a groove already set in the end of the block to receive the control joint.

Typically, this product is made from PVC (polyvinyl chloride) or rubber. Rubber control joints tend to perform better than PVC. Notice the black control joint depicted on the end of the wall.




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Ties come in many forms, “hook and eye” being the most common. Eyes are welded to the masonry joint reinforcing and protrude out just far enough for the eye to clear the insulation. Remember, since this eye has entered the cavity, it must be a minimum 3/16″ in diameter by code.

To complete the reinforcing of the brick veneer wall or wythe, a double hook is inserted into the eyes and lays over onto the brick. This “hook” should lay a minimum of 1½″ onto the brick. The hook should be held back from the outside surface of the brick wall about 1″.

Code states that the outside mortar coverage of the tie should be a minimum of ⅝″. So, if you hold the tie back about 1″ and compress or “tool” the mortar joint, you should then be code compliant. Remember the spacing is typically 16″ o.c. vertical and 16″ o.c. horizontal. These ties are now able to transfer the positive and negative wind loads to the stronger CMU.




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Today’s Block Backup Cavity Wall: Moisture Management

Up to this point, we’ve dealt with structural items. Now let’s take a look at moisture management.

You will notice that the image on the previous slides shows a stainless steel drip edge flashing on the outside wall just below the level of the interior finished floor. Weeps are installed down to the surface of the drip edge a minimum 24″ o.c. allowing any water to drain from the cavity. Additional weeps are sometimes installed to increase drainage and increase air flow in the cavity. Air flow can be improved by adding weeps at the upper portion of the wall, allowing the air to actually circulate. There are many types of weeps as you will see later. The design of the weep should allow good air movement and a screening capability to stop insect intrusion into the cavity.

Although not shown clearly on this image, weather barriers are usually applied to the face of the CMU. These can be sprayed, brushed, or rolled onto the wall prior to installing the flashing (seen in gray on image). If a sheet good is used then it would lap over the gray flashing creating a shingled effect. Shedding and directing water to the cavity and out of the masonry wall system is as important as the wall’s structural capability.




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The use of a “mortar droppings collection device” is now the preferred method. Notice the blue material in the cavity. This material is made of polypropylene. The strands are randomly woven together creating a product that is 90–95% air. This product comes in various thicknesses to accommodate varying cavity dimensions. The product can be rectangular in shape or a “dovetail” shape as indicated. The product catches the mortar droppings allowing water to still pass through to the weeps. The dovetail shape works well by keeping mortar away from the under portion of the dovetail.

Flashing is often made in a “peel and stick” configuration. The flashing itself is a composite of a release paper, some type of glue base such as butyl adhesive, rubberized asphalt, etc. and an outer layer of stainless steel, copper, polyester scrim, and others. Since it is important for the flashing to remain in place on the side of the wall, a small, flat bar is mechanically installed at the top edge of the flashing. A bead of chalk is applied to the top edge of this “termination bar.”

As the exterior masonry “veneer” wall is being installed, the mason is expected to keep the cavity clear of any mortar droppings that might block the weeps. The normal way to do this is to take the trowel and flatten the excess mortar to the back of the wall. In the past, wooden sticks with strings attached to each end were dropped into the cavity with the expectations of drawing the stick up and bringing any mortar droppings along with it. This seldom worked well and is typically not done today.




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Developing the Masonry Structures Code




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Masonry Reinforcing

What forces act upon a masonry wall? What environmental impacts should be taken into account—wind, seismic, rain, etc.?

Many things go into designing masonry walls. When dealing with wind, it’s important to remember that wind can create a compressive load on the brick as it blows against the wall. As the wind whips around and over the building, tension loads can actually act upon the wall trying to pull the brick or stone off of the wall. How these wythes in a wall work with the ties holding them together is all part of the masonry structures code.




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Seismic Concerns

Other concerns can come from seismic conditions. As the ground shakes and moves in an earthquake, the masonry ties need to transfer the loads between the two wythesaccordingly.

The ties still need to keep the wall from deforming or bending to the point that the mortar joint cracks and lets in too much water from wind-driven rain. Additional wire or rods are added in the exterior brick wythe to give added strength. You will see examples of this later in the presentation.




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Code Requirements

To understand more about the design of masonry walls and their code requirements, you might look to the information provided by a number of associations. The Brick Industry Association (BIA) is a great first search for technical information and details, www.gobrick.com.

The International Masonry Institute is developing BIM-M (Building Information Modeling for Masonry), a source for the industry to come together and offer architects, designers, and contractors good generic details for the masonry industry, www.imiweb.org.

The Masonry Society www.tms.com, American Concrete Institute www.aci.com, Structural Engineering Institute http://www.structurescongress.org/, and Mason Contractors Association of America www.mcaa.com are all excellent resources.

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Building Code Requirements and Specifications for Masonry Structures

Through the work done by the various associations, a committee was formed by three of them in 1989. This committee was made up of representatives from the Masonry Society, the American Concrete Institute, and the Structural Engineering Institute. This group was known as the Masonry Standards Joint Committee (MSJC).

The document they created was Building Code Requirements and Specification for Masonry Structures (TMS 402-13/ACI 530-13/ASCE 5-13). This document comprises code requirements, specifications, and commentaries. (Since it was written by many engineers, they broke it down into verbiage that us regular guys can understand in the commentary section.) Going forward in this presentation, you may see the codes referred to as “TMS 402” or simply “code.” Sizing, material type, spacing, etc. is typically found in this book.




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Joint Reinforcing for Single-wythe Walls




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Truss Type Joint Reinforcing

Twenty years ago, truss type reinforcing was the norm when it came to joint reinforcing. It comprises two elongated steel rods and a welded diagonal rod, either 9 gauge or 3/16″ diameter.

The diagonals tended to get in the way of grout pours and reinforcing bars that might be called for in the cells of the block.

In general, truss type reinforcing is too strong for cavity walls but is still okay for single-wythe walls.

Masonry joint reinforcing and rebar is typically called out and sized by the structural engineer.




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Ladder Type Joint Reinforcing

Ladder type reinforcing is now the preferred product for CMU walls. It comprises two elongated rods and a cross rod (either 9 gauge or 3/16″ diameter) at 16″ on center.

The 16″ on center design positions cross rods on the center web of block to allow core clearance. This simplifies rebar installation, allows unrestricted flow of grout or loose fill insulation into CMU cells, and provides a stronger bond with cross rods in the center web of block.




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Ladder Corners and Tees

Truss or ladder corners and tees are available for all joint reinforcement sizes. Typical lengths are 30″. Code dictates that you should splice or overlap ends of reinforcement a minimum of 6″ with adjacent reinforcement.

In addition, the reinforcing should be kept back from the outside face (weather side) about 1″ to allow for ⅝″ mortar coverage once tooled.




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Functions of Joint Reinforcing

Joint reinforcing strengthens the mortar joint, which helps control shrinkage cracking. It bonds masonry wythes together in composite and cavity walls. One-inch air space is required, but 2″ is recommended.

Joint reinforcing also allows loads to be transferred from the brick veneer to the stronger CMU or metal stud backup, bonds intersecting walls, and increases the wall’s flexural strength.




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Wire Sizes and Finish Descriptions for Ladder and Truss Reinforcing

Wire Gauges Side Rods Cross RodsStandard 9 ga. 9 ga.Heavy duty 3/16″ 9 ga.Extra heavy duty 3/16″ 3/16″

Finish DescriptionMill galvanized Zinc coated (.10 oz/ft); used for interior masonry walls only.Hot dipped after fabrication 15x more zinc than mill galvanized (1.5 oz/sq ft), minimum required for exterior

walls. Stainless steel Type 304 stainless is the best product for high humidity and caustic environments.




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Reinforcing Wire Deformations

ASTM A 951—Standard Specification for Masonry Joint Reinforcement.

Longitudinal wires shall be deformed. One set of two deformations around the wire shall occur at not less than eight sets per inch. This helps with the adhesion of mortar to the wire.




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Joint Reinforcing Installation

Lay reinforcing on the wall in advance of the mortar. Apply mortar to bed joint. Since wire is round and not flat, mortar will surround the reinforcing and no lifting is required.

Position side rods allowing a minimum of ⅝″ coverage between the reinforcement and the exterior face of mortar.

When using ladder type, always keep the cross rods in the web of the CMU.

To meet requirements of TMS 402/ACI 530 code, ends of ladder must overlap creating a splice of at least 6″. To ensure bonding in bed joint, the height and thickness of the reinforcement shall not exceed half the thickness of the mortar joint. Three-eighths of an inch mortar joint equals 3/16″maximum reinforcement height.




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Joint Reinforcing for Multi-wythe Walls




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Ladder 3 Wire, 4 Wire, & Fixed Tab

Ideally, the types of reinforcement shown (Ladder 3 Wire, 4 Wire, and Fixed Tab) work best when the brick and the block course out evenly.

On jobsites it is typical for the CMU to be installed first, since it is the load-bearing portion of the wall. It is the part of the wall that carries the weight of the wall, floors, and roof above. This allows for the project to proceed quicker. Later as the brick or stone veneer is installed, the mason will typically bend the reinforcing out of the way that is hanging out of the block every 16″ on center vertically. The mason then tries to bend the reinforcing back down to the top of the brick or stone veneer. This simply doesn’t work. This is where adjustable ties came into play and are now the norm.




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Level Ladder Hook and Eye

As stated earlier, the level ladder hook and eye is probably the most common adjustable tie for CMU backup on the market. Several things are required by code for all masonry ties.

1. Any reinforcing steel used to tie the veneer brick or stone back to the stronger backup wall that crosses the cavity shall be a minimum of 3/16″ in diameter.

Double eyes welded level to ladder at 16″ o.c., maintaining 3/16″ max wire height in ⅜″ mortar joint.

Max 1/16″ tolerance where hook intersects eye as per code.

Hook design allows for 1¼″ vertical adjustment.

Legs of hook hold 16″ high insulation in place during construction.




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Level Ladder Hook and Eye

2. Since the brick or stone veneer is typically laid sometime after the CMU, the tie will have an adjustment of at least 1¼″ vertically to accommodate potential uneven coursing between the two wythes. At the end of the 1¼″, the tie should have a bend or loop to discourage disengagement.

3. Where the 3/16″ diameter tie interacts with the 3/16″ diameter loops or “pintle” coming from the stronger backup wall, no more than a 1/16″ tolerance is allowed. This minimizes excessive movement as the wind changes from a push/pull load.

4. The hook should lie at least 1½″ onto the brick from the cavity side and have at least ⅝″ mortar coverage from the weather side.

5. As per the Brick Industry Association, each tie should be able to withstand a minimum 100 lb load in either tension or compression.




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New Energy Codes = More Insulation

The new International Energy Conservation Code (IECC) went into effect across the US in January 2015. This code requires better R-values than previously required. Architects are specifying thicker insulation to meet these requirements. Where total space between the back of the brick to the face of the block might have been 3½″–4½″, it is now being extended to 6″ or better.

IECC: International Energy Conservation Code & ASHRAE 90.1-2013




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Reinforcing Size

It is important that the architect, dealer, or contractor convey these four dimensions so the manufacturer can supply the correct products for the job. The manufacturer will know which products, sizes, and material will work best and meet the codes.

The manufacturer needs four dimensions:

1. Block size (6″, 8″, etc.)

2. Insulation thickness

3. Air space

4. Brick size (4″, etc.)




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Need Something Stronger?

Tornados, hurricanes, and safe rooms might require even more strength from the adjustable ties, keeping the brick on the wall and not on your head.

Manufacturers are making various types of pintles that began their life as a hook. The leg has been extended and looped back on itself making the pintle virtually impossible to disengage.

Code requires ties to be 3/16″ wire and to be adjustable a minimum of 1¼″ should the brick not course out evenly.

They are installed at 16″ vertically and 16″ horizontally.




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Stronger Hooks

Stronger hooks are great for wider cavities, thicker insulation, and higher wind loads. As mentioned in the previous image, stronger ties might be required in very high wind loads. About one-third of the country now requires schools and some public spaces provide a “safe room” where all students and teachers can gather in an emergency.

These rooms need to be able to withstand an EF-3 tornado. If the contractor is already accustomed to using hook and eye, why not simply increase the tensile strength of the steel, thus increasing the overall performance of the tie by as much as 2½ times.

Hooks fabricated from high tensile strength spring wire are simple, yet over 2 times stronger than standard hooks.

The hook maintains a 3/16″ diameter allowing it to be used with the standard level eye products. Remember that whatever the material used to manufacture the hook, the same material should be used on the eyes.




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Cavity Walls With Steel Stud Backup

When it comes to the walls that back up masonry and stone veneers, steel stud walls are more common than CMU. Most of the components are the same as CMU backup with the exceptions of the masonry joint reinforcement and the types of ties.

Since there is no CMU, the masonry joint reinforcement will not exist. The ties, as opposed to being “hooked” to the sides of something welded to the side of the joint reinforcement, are now attached through the insulation and/or sheathing back to the metal stud.

You might also notice on this image that a butyl tape is used all the way up the wall at the tie locations. This acts as a gasket material around the screw at the tie.

• Strong• Economical• Energy efficient• Low-maintenance• Built to last




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Various Types of Adjustable Ties for Steel Stud Backup

Post Type w/ Triangle Plate w/ Hook Type lll w/ Triangle

Plate w/ Triangle Plate w/ Hook Type lll-X w/ Triangle

Since there are only two or three manufacturers of adjustable metal ties in the country, it is sometimes difficult to have a generic term that describes the tie. The images you see show six typical adjustable ties from the masonry industry for steel stud backup.




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Various Types of Adjustable Ties for Steel Stud Backup

As shown on the previous slide: the top left image is a “post type” tie that works for all types of backup walls, which we will discuss in more detail later.

The top center is a “plate with hook” that requires at least two fasteners. This plate should be installed on the face of the gypsum or plywood sheathing and weather barrier if one exists. The prongs on the plate will extend to just beyond the insulation so that the hook can be inserted. There are three holes in the plate and we would like to see one of the two anchors in the center hole. The center hole is more in line with the hook when in tension and better distributes the load.

The top right is a “type III with triangle.” This tie offers a lot of vertical movement. It is acceptable to be placed over all types of substrates, but not over insulation. Two fasteners are required.

The bottom left is a “plate with triangle tie” that would work at the ends of rigid insulation or with possibly sprayed-on insulation.

The bottom center and bottom right are similar to the ties above them on the previous slide. The difference is that they now include teeth or prongs designed to be driven through the sheathing and/or insulation. The teeth are expected to hit the stud beyond. These products require the contractor to hit the center of the stud, which crushes the sheathing or insulation in the process.




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Adjustable Anchor & Tie Requirements

Anchors that connect the veneer to the backing must provide out of plane support, resisting tension and compression, but allowing shear. Anchors must be embedded at least 1½″ into the brick veneer with a minimum mortar coverage of ⅝″ on the outside face of the wall.

Maximum clearance between connecting parts of the tie shall be 1/16″. Adjustable anchors shall be detailed to prevent disengagement. Pintles (double hooks) shall have at least two 3/16″ legs and shall have an offset not exceeding 1¼″.

Horizontal and vertical spacing shall not exceed 16″ o.c. Wall ties shall be without drips. Minimum air space shall be 1″ per code, but 2″ is recommended by all industry associations.

Maximum void between steel framing and inside face of veneer is 4½″ by code, but manufacturers are starting to move to products with wider cavities to accommodate the new energy codes.

Provide 9 gauge rod/wire horizontally in veneer for seismic zones E and F.




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Plate with Hook and Type lll Anchoring Systems

Plate w/ Hook Type lll w/ Triangle

Two holes above legs helps with installation when insulation used.

Hook allows 1¼″ up and down movement.

Rubberized tape creates a seal where screws penetrate.

Seismic wire attaches to tie at brick wythe.




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Post Type Anchoring System

As mentioned earlier, we are now going to discuss a post type anchoring system. This type of tie is really growing in popularity. It is installed in any type of substrate. In CMU and concrete, a pilot hole is drilled to 3/16″. Then a ¼″ tapconscrew with a special head is driven into the wall. It can go through insulation or sheathing. Since there is a rubber washer already attached to the specialized screw head, no butyl tape is required.

This type of post anchor creates only one hole instead of two. The screw comes in two types of finish. The tapcon finish is used for concrete, CMU, and wood. An anti-corrosion finish with a cutting tip is available for steel studs. A self-drilling tip means no pilot holes. All screws come in various lengths to accommodate varying insulation thicknesses. A special chuck is available to fit in any drill for easy installation.

Tapcon screw allows positive contact with wood and concrete.

A screw with anti-corrosion finish accommodates sheathing and various thicknesses of insulation.

A specially designed chuck allows the post type anchor’s slotted head to easily slip in with a straight and snug fit.




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Post with Triangle Anchoring System

As seen in the image, a 3/16″ diameter triangle is attached when it is time to lay the exterior masonry. Notice the design of the triangle allows for 1¼″ vertical movement and only a maximum 1/16″ back and forth movement where the triangle connects to the screw as per code.

All three of the tie manufactures produce a similar product. These ties work with all substrates and keep it simple for the architect and masonry contractor.

Note seismic clip and continuous wire.

Only one hole penetrates the wall instead of two.




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Post with Triangle Anchoring System

Note that ties in masonry walls are considered by three sources to add no appreciable thermal conductance.

1. When the new International Energy Conservation Code (IECC) was adopted 1/1/2015 it stated, “the code does not require a reduction in R-value calculation for masonry ties, fasteners, or anchors.”

2. The American Society of Heating, Refrigerating, and Air-conditioning Engineers, (ASHRAE) in their report, “Thermal Performance of Building Envelope Details for Mid-rise and High-rise Buildings” (5085243.01 MH 1365-RP July 6, 2011) states, “Brick ties are considered a clear field anomaly, and are not considered practical to take into account on an individual basis for whole building calculation.”

3. In August 2015, Architectural Testing, Inc. constructed two 8′ x 8′ brick veneer walls, one with ties and one with no ties to gauge the thermal conductance of the ties. The walls were ½″ drywall, 16 gage, 2 x 6 metal studs, 16″ on center, 5/8″ gypsum sheathing, 2″ rigid insulation board, 1″ nominal air space, masonry ties at 16″ on center both vertically and horizontal, 4″ nominal common red brick. In conclusion, “The wall assemblies, as tested, performed identically in terms of U-Factor and R-Value” and “fasteners do not create any significant thermal bridging effects on this wall system.”




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Rebar Positioners

When rebar is grouted into cells of CMU, it is important to locate the reinforcing where the structural engineer intended. Usually it is in the center of the cell since the wind loading can put the wall in either tension or compression.

Since these rebar positioners are laid in wet mortar, movement is typical from the weight of the rebar. They should be placed about every 4′ vertically.




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Recessed Rebar Positioner

A better solution for holding the rebar in place is a recessed rebar positioner. This type of rebar positioner is rigidly held in place by the CMU and is not dependent on the wet mortar, ensuring that you keep the rebar where the structural engineer wants it. All rebar positioners are available for both single and double reinforcing bars plus the splice.

Installs 1¼″ deep instead of on top of the block.

Does not interfere with ladder wire reinforcement.

Design prevents any movement during installation.

Code requires that rebar be kept in center of block cell.




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Stone Anchors

Stone is another type of veneer that still needs to be anchored back to the substrate. Typically, when laying irregularly shaped stone, a pencil rod system might be used. This allows triangles to move vertically up the rod and randomly lay in the mortar joints as the stone shape might require.

Tabs are welded to the truss or ladder type joint reinforcing and a 3/16″, ¼″, or ⅜″ diameter “pencil rod” is slid through the tab vertically. Next a 3/16″ diameter lock bar triangle or dovetail triangle is slid onto the pencil rod. Components are either hot-dipped galvanized steel or stainless steel.




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Stone Anchors

When the stone veneer is cut even with square edges, a slot or hole is cut or drilled into the edge of the stone. The manufacturer will usually determine how many anchors they might need per stone piece. These anchors are normally ⅛″–½″ thick stainless steel. In situations where holes are drilled into the edge of the stone, anchors with a dowel might be provided.

These types of anchors, both slot or dowel, are usually rigidly attached back to the substrate. Fasteners used to attach the anchors to the substrate will vary. They can be attached with expansion bolts when tied back to masonry.




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Flashings, Mortar Dropping Collection Devices, and Weeps




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Basic Types of Flashing

As you have seen some of the developments of masonry walls, other than improving the structural capabilities, dealing with the possible water intrusion into and through the wall are just as important. Just as shingles on the roof are designed the shed water off and away, the same applies to flashing in a masonry wall.

Flashing details associated with masonry walls can be found through the Brick Industry Association and the International Masonry Institute. In this presentation we will deal with some of the basic types and where they might be used.

Flashing termination bar caulked along top edge.

Drip edge flashing made from 304 stainless steel.

Flashing comes in a wide variety of materials. Trowel applied mastics, polyethylene and rubberized asphalt composites, peel & stick, copper fabrics, etc.




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Types of Flashing

PVC: Non-reinforced polyvinyl chloride sheet:Use in milder climates because it can become rigid and brittle under severe freeze-thaw conditions.Use on concealed foundation walls, under slab, and thru-wall flashing.

Polyethylene/Rubberized Asphalt: Can be used in all climates, is peel and stick. Sticks to concrete, steel, wood, and gypsum.Use for thru-wall, foundation sill, base, parapet head and sill.

Polyester scrim/Thermoplastic:Many companies use thermoplastic product, a ketone ethylene ester (KEE). Used with a polyester scrim and butyl adhesive it works very well. For use in all climates, is peel and stick. Resists oil and most chemicals, will not drool, no UV degradation, and is considered the best non-metallic peel and stick.




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Types of Flashing

Copper Fabric: Copper sheet laminated between blended asphalt and glass fabric:3, 5, and 7 oz copper. Excellent for thru-wall and surface applications with no drool.

Copper/Rubberized Asphalt: 3 oz copper sheet with polyester film one side and rubberized asphalt on the other. It is highly adhesive. Rubberized asphalt has a greater longevity compared to standard asphalt.

Please remember the exam password FLASHING. You will be required to enter it in order to proceed with the online examination.




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Mortar Droppings Collection Device and Weeps (MDCD)

The basic idea is to allow any water that might get through the exterior veneer to be stopped by the flashing, fall or run down the cavity and be weeped out of the cavity through weeps at 24″ on center horizontally. In general, the MDCD should be in the bottom of the cavity to catch any mortar that might fall into the cavity while laying the exterior brick wall. The MDCD keeps the weeps clear. Weeps can come in many types. When selecting weeps, consider the following.

1. Weeps should allow water to exit the cavity.2. Weep should stop insects from entering the cavity from outside.3. Recently there has been a push by the design community to add more weeps in an effort to increase the air flow or

convection of air in the cavity. Twenty-four feet o.c. horizontally is the maximum spacing by code. Adding weeps under windows and at the tops of walls is also a good idea.

4. Select weeps that offer more airflow by their design.5. Selecting weeps that more closely match the mortar color is usually a good idea for aesthetic reasons.




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Mortar Droppings Collection Device (MDCD)

This MDCD is made of a polymer core composed of high density polyethylene strands woven into a thick mesh. The product is 90–95% air. Thickness varies based on the cavity width. Keeping the MDCD slightly narrower than the cavity helps prevent any possible bridging of mortar across the cavity. A better design is the dovetail shape. The dovetail creates an overhang preventing mortar from building below.




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Clear Round Weepholes

They are available with a filter and a wick. Thistype of weep circulates little air, or none with a wick.

Install a minimum 24″ on center as per code.




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Clear Rectangular Vent

They are available with a filter and a wick.

Install 24″ on center as per code.




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Cavity Net Weep

Made similar to the MDCD material shown in blue, this weep solves many issues:

1. Fits firmly in brick head joint2. Is 90–95% air (great air flow)3. Stops insects from entering cavity4. Is available in various colors from many manufacturers




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Cell Vent

The cell vent is an ultraviolet resistant polypropylene co-polymer that allows for good air flow and stops insects. It is available in many colors.




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Conclusion

If you desire AIA/CES, state licensing or CE credits for another organization, please click on the button to commence your online examination. A score of 80% or better will allow you to print your Certificate of Completion; you may also go to your AEC Daily Transcript to see your completed courses and certificates.

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©2016 Wire-Bond. The material contained in this course was researched, assembled, and produced by Wire-Bond and remains its property. Questions or concerns about the content of this course should be directed to the program instructor. This multimedia product is the copyright of AEC Daily.

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Slide 1Proper Use of Masonry Joint Reinforcement and AccessoriesSlide 3Purpose and Learning ObjectivesHow to Use This Online Learning CourseTable of ContentsA History of Masonry WallsA Brief History of Masonry WallsMesopotamiaPyramids of GizaMud BrickEarly Masonry WallsWind-driven RainEarly English Cavity Wall Wall Ties in the 1800sBrick AlternativeConcrete ExteriorToday’s Block Backup Cavity Wall Today’s Block Backup Cavity Wall Today’s Block Backup Cavity Wall Today’s Block Backup Cavity Wall Today’s Block Backup Cavity Wall: Moisture ManagementToday’s Block Backup Cavity Wall Developing the Masonry Structures CodeMasonry Reinforcing Seismic ConcernsCode RequirementsBuilding Code Requirements and Specifications for Masonry StructuresJoint Reinforcing for Single-wythe WallsTruss Type Joint ReinforcingLadder Type Joint ReinforcingLadder Corners and TeesFunctions of Joint ReinforcingWire Sizes and Finish Descriptions for Ladder and Truss Reinforcing Reinforcing Wire DeformationsJoint Reinforcing InstallationJoint Reinforcing for Multi-wythe WallsLadder 3 Wire, 4 Wire, & Fixed TabLevel Ladder Hook and EyeLevel Ladder Hook and Eye New Energy Codes = More InsulationReinforcing Size Need Something Stronger?Stronger HooksCavity Walls With Steel Stud BackupVarious Types of Adjustable Ties for Steel Stud BackupVarious Types of Adjustable Ties for Steel Stud BackupAdjustable Anchor & Tie Requirements Plate with Hook and Type lll Anchoring SystemsPost Type Anchoring SystemPost with Triangle Anchoring SystemPost with Triangle Anchoring System Rebar Positioners Recessed Rebar PositionerStone AnchorsStone AnchorsFlashings, Mortar Dropping Collection Devices, and Weeps Basic Types of FlashingTypes of FlashingTypes of FlashingMortar Droppings Collection Device and Weeps (MDCD)Mortar Droppings Collection Device (MDCD) Clear Round Weepholes Clear Rectangular VentCavity Net WeepCell VentConclusion

proper use of masonry joint reinforcement and accessories · 2016-09-09 · masonry joint...

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