Brick ties are an important component in masonry construction. They serve to connect multiple wythes (layers) of masonry, often of different materials, and anchor masonry veneers to backing systems.
While hidden from view in the finished wall, brick ties play a vital role in structural integrity, moisture management, and overall building performance.
Key Functions of Brick Ties
Brick ties serve three primary functions in multi-wythe masonry walls:
- Connection – Securely join adjacent wythes allowing them to act together structurally
- Load transfer – Transmit lateral loads from one wythe to another or to backing
- Accommodate movement – Allow in-plane movement between wythes to manage differential movement
To properly fulfill these roles, an effective brick tie system should:
- Securely bond to both wythes with adequate embedment
- Provide sufficient stiffness to transfer loads without excessive deformation
- Allow minimal mechanical play for stability
- Use corrosion-resistant materials for durability
- Be easily installed to minimize errors and damage
When selecting ties, all of these criteria should be weighed carefully. While cost is a factor, it should not override performance requirements.
Design Considerations for Brick Tie Selection
Numerous factors come into play when determining the optimal brick tie selection for a given project:
- Structural system – Brick ties for multi-wythe masonry differ from veneer applications.
- Cavity width – Wider cavities to accommodate insulation may require deeper ties.
- Movement allowance – The expected differential movement affects tie flexibility needs.
- Material type – MortarJoints of dissimilar materials often require more movement capacity.
- Wall height – Taller walls require stronger, stiffer tie systems.
- Wind loads – Higher wind pressures demand greater tie capacity.
- Corrosion resistance – Environmental exposure impacts required protection.
- Constructability – Ease of proper installation must be considered.
With so many variables, it’s advisable to consult with an engineer to determine the optimal tie specification for each unique project. Manufacturers can also provide recommendations based on their product testing and recognized standards.
Multi-Wythe Masonry Tie Types
There are several categories of brick ties used in multi-wythe masonry construction:
These are individual metal ties installed at prescribed intervals in the mortar joints. Common types include:
- Rectangular ties – Simple wire box ties used in hollow or solid brick and block walls
- Z ties – Wire ties for composite walls with interlocking masonry units
- Corrugated ties – Formed sheet metal ties often used in residential veneers
These two-piece systems allow vertical adjustment between wythes. Common types include:
- Pintle and eye – Wire ties with double pintle legs and anchor eyes
- Channel slots – Ties fit into slots cast in concrete BackupBackups
- Dovetail anchors – Ties insert into dovetail reglets in concrete or masonry
Horizontal metal rods installed in mortar beds tie walls together. Types include:
- Ladder joint reinforcement – Longitudinal wires with perpendicular cross rods
- Truss joint reinforcement – Additional diagonal cross rods for stiffness
These combine joint reinforcement with adjustable pintle/eye ties for easy installation.
Veneer Tie Anchors
Brick veneer ties secure the masonry wythe to the structural backing. Common anchors include:
- Corrugated ties – Sheet metal ties nailed to wood or screwed to steel studs
- Wire pintle anchors – Wire ties insert into eyes, channels or dovetails
Selection Guidelines by Building Type
Simplified tie selection guidelines per masonry standard AS/NZS 2699.1:
- Type 1 – Heavy duty, rigid tie for high-rise buildings
- Type 2 – General purpose tie for smaller commercial/residential
- Type 3 – Basic tie for lower wind speeds
- Type 4 – Light duty tie for single-story residential
- Type 5 – Residential veneer up to 3 stories
- Type 6 – Residential/small commercial up to 4 stories
- Type 7 – Mid-rise residential up to 7 stories
Consult standards for specific limitations and engineered design needs.
Brick Tie Material Considerations
Brick tie material selection is another key factor, as it impacts both performance and durability.
Carbon Steel – Galvanized or epoxy-coated carbon steel ties offer strength, stiffness, and economy. Galvanizing provides corrosion resistance through zinc’s sacrificial protection. Epoxy coatings act as a moisture barrier.
Stainless Steel – Stainless steel ties resist corrosion without coatings required by carbon steel. However, some stainless alloys are needed to avoid galvanic corrosion when combined with carbon steel components.
Non-metallic – Materials like fiberglass and nylon provide high strength without corrosion concerns. However, these ties may have higher thermal conductance.
Composite – New engineered composites like basalt fiber ties offer an alternative to steel with excellent corrosion resistance. They also reduce thermal bridging.
Your structural engineer can recommend appropriate materials for the project conditions. Stainless steel is common in many residential and commercial applications.
Proper Brick Tie Installation
To function as designed, brick ties must be properly positioned and embedded within the masonry wythes:
- Ties should be fully mortared in place, not dry-laid in a joint
- Embed each end of the tie at least 1.5 inches (38mm) into mortar
- Embed ties at least 1 inch (25mm) into mortared shells of hollow CMUs
- Place ties close to the center of cavity walls and tilt slightly down
- Position ties staggered in vertical columns at 16 – 24 inches on center
Verify all ties are straight, aligned correctly, and spaced accurately to prevent future problems. Take extra care installing adjustable ties to allow full engagement with both wythes. Consult manufacturers for any specialty installation instructions.
Frequently Asked Questions
What is the primary purpose of brick ties?
The main role of brick ties is to securely connect adjacent wythes of masonry to improve structural performance and stability. They also help manage moisture penetration.
How many brick ties should be installed per square foot?
Common practice is to install brick ties staggered at 16 to 24 inches vertically and horizontally in a wall at a density of around 2.5 ties per square foot. More ties are concentrated around openings and boundaries.
When are deeper brick ties needed?
If the cavity width exceeds around 4 inches to allow thicker insulation, deeper adjustable ties may be required. The span length is a more critical factor than cavity width.
Can corrugated metal ties be used in all wall types?
Corrugated sheet metal ties are appropriate for residential veneers over wood framing but not other wall types like multi-wythe masonry cavity walls.
What is the advantage of two-piece adjustable brick ties?
They allow the exterior wythe to be installed after the structural BackupBackups, and accommodate minor vertical alignment differences between wythes.
Specifying the optimal brick tie system relies on a clear understanding of tie types, functions, and proper installation. With their critical yet hidden role, brick ties deserve careful consideration as part of the overall wall system design. By following the recommendations in this guide, you can select durable, compatible brick ties tailored to your specific project requirements. With the right ties properly installed, you can have confidence in your masonry wall performance.