Structural and base materials · Masonry & Blocks
Wall Ties for Cavity and Masonry Walls
Treats wall ties as an assembly component: what they do in a cavity wall, why their type and arrangement are engineering decisions, and how corroding ties in older walls make themselves known.
Educational reference entry. Suitability depends on the complete assembly, substrate, exposure, installation method, manufacturer documentation, local requirements and qualified professional review.
Overview
What wall ties is
Wall ties are metal components built into the bed joints of masonry to connect one leaf of a wall to another, or to tie masonry back to a structural frame. In a cavity wall they hold the outer and inner leaves together so the two act with each other rather than independently, while still allowing the cavity to do its job.
They are made in several forms: drawn wire ties of various shapes, flat sheet ties, and helical ties driven or resin-fixed into existing walls as a remedial measure. Material choice matters because a tie sits in a damp, alkaline bed joint and is expected to stay there indefinitely; stainless steel is common in current work, while much older walls used protected mild steel.
Type, length and arrangement are engineering decisions, not something to be resolved on site with whatever is in the van. A tie also has to avoid becoming a bridge for moisture across the cavity, which is why its orientation in the joint matters, why the cavity is kept clear of mortar droppings, and why many ties carry a formed drip. Ties are built in as the masonry rises; pushing them into finished work is a different operation entirely.
Terminology
Common names and aliases
These names describe the same thing. The library keeps one entry per material so that an acronym, a trade name or a regional spelling never becomes a second, thinner page.
- Cavity wall ties
- Masonry ties
- Brick ties
Applications
Common applications
Where this material is typically encountered. A typical application is not a statement that it suits your project.
- Connecting the outer and inner leaves of a cavity wall as the masonry is built up.
- Restraining a masonry outer leaf back to a timber, steel or concrete frame.
- Tying new masonry into existing walls where the two are built at different times.
- Remedial work, where original ties have corroded and replacements are installed into finished walls.
- Holding cavity insulation in position, where the tie carries a retaining clip as it is built in.
Consideration
Where it is commonly considered
- Wherever a cavity wall is built, since the two leaves have to be connected in a designed way.
- Where masonry is supported by or restrained back to a frame rather than standing on its own.
- Where an existing wall shows signs that its original ties may be failing.
- Where new masonry is being bonded or tied into an existing wall as part of an alteration.
- Where cavity insulation needs retaining against the inner leaf as the work proceeds.
Professional review
Where additional professional review is especially important
These are the situations where the answer depends on the specific building, and where a qualified professional should be involved before anything is decided.
- Substituting a different tie type or material for the one specified, since that changes the design.
- Using ties recovered from another job, or ties of unknown material, in a damp bed joint.
- Relying on remedial ties without an assessment of why the original ties failed.
- Installing ties into an existing wall without knowing what the leaves are actually made of.
- Assuming that a tie designed for one cavity arrangement will suit a different one.
Properties
Key properties to discuss
Qualitative topics worth raising. Measured values, classes and grades come from the manufacturer's technical documentation for the specific product, not from a reference page.
- Installation dependency
- Ties are built in as the wall rises, bedded properly in mortar at both ends and set in the orientation the design requires. A tie sitting in a void, or sloping the wrong way, is worse than no tie at all.
- Moisture behaviour
- A tie crosses the cavity, so it can carry water across if it is fouled with mortar or wrongly orientated. Formed drips and a clean cavity are what stop a tie becoming a path for moisture.
- Substrate dependency
- What the tie is fixed into governs the choice: masonry bed joints, a timber frame, a steel frame and a concrete structure each call for a different component.
- Weathering and exposure
- Ties live in a damp, alkaline joint. Corrosion of older protected steel ties expands the metal, which can lift the bed joints of the outer leaf and show as regular horizontal cracking.
- Maintenance
- Ties are hidden, so problems are found indirectly, through cracking patterns, bulging of an outer leaf, or a survey using instruments that locate the ties within the wall.
- Repairability
- Failed ties are usually addressed by installing remedial ties into the finished wall rather than by taking the wall down, which is specialist work carried out after an assessment.
- Documentation
- The specification should record the tie type, material and arrangement, and for remedial work the survey findings and the installer's own records are what future owners will need.
Exposure
Exposure and environmental conditions
- How exposed is this wall, and does that affect the tie material that should be chosen?
- Is the building coastal or in an aggressive atmosphere where corrosion is more of an issue?
- Is the cavity likely to be wet, and can water that reaches it get out at the base?
- In an older building, is there a history of damp or cracking that might relate to the ties?
- Has the cavity been filled with insulation, and does that change the environment the ties sit in?
Assembly
Substrate and system dependencies
What this material sits on, is fixed to or depends on. This is usually where performance is won or lost.
- The width of the cavity and the leaves being connected together determine which tie can be used.
- Where insulation sits in the cavity, the tie usually carries a retaining clip and the two have to match.
- Ties around openings, at movement joints and at the edges of panels are arranged differently from those in the field of a wall.
- Where masonry is tied back to a frame, the fixings into that frame are part of the structural design.
- Mortar droppings left on ties are a construction issue that no tie design can overcome.
Appearance
Appearance and finish considerations
- Ties are concealed within the wall, so they have no direct effect on how a completed elevation looks.
- Remedial ties installed into a finished wall leave made-good positions that can be visible on a fair face.
- Where original ties have corroded, the visible symptom is regular horizontal cracking in the joints of the outer leaf.
- Bulging or bowing of an outer leaf is a visible sign that the connection between the leaves may be in question.
Durability
Durability questions
Questions to raise rather than a service life to expect. No material has a universal lifespan — it depends on the assembly, the exposure and the upkeep.
- What material are the ties made from, and does it suit the conditions inside this cavity?
- In an existing building, does anyone know what ties were used and whether they have been surveyed?
- Is there evidence of horizontal cracking at regular intervals that would suggest tie corrosion?
- Have the ties been kept clean during construction so that mortar cannot bridge the cavity?
- Where remedial ties are proposed, has the cause of the original failure been established?
Upkeep
Maintenance and repair considerations
- How would the condition of concealed ties be assessed without opening up the wall?
- If remedial ties are installed, who specifies their type and their arrangement?
- What happens to the corroded original ties, and are they simply left in place?
- How will the made-good positions be finished so that they do not read as patches?
Installation
Installation dependencies
What the installation depends on — not how to do it. Method belongs to the manufacturer's instructions and the trades carrying out the work.
- Ties are built in as the masonry rises, which means the two leaves have to progress together.
- Both ends of a tie need proper embedment in mortar, not a token bed at one end only.
- The cavity is kept clear of droppings as the work proceeds, since cleaning it afterwards is very difficult.
- Additional ties are placed at openings, at the ends of walls and at movement joints as the design requires.
- Remedial installation into an existing wall is a different trade operation with its own equipment and method.
Documentation
Documentation to request
Ask for these in writing, for the specific product being proposed, and keep them with the project record.
- The specification stating tie type, material and arrangement for each part of the building.
- The manufacturer's data for the specific tie, including which cavity arrangements it is intended for.
- For remedial work, the survey report that established the condition of the original ties.
- A record of where additional ties were required and the reason they were needed.
Conversations
Questions for qualified professionals
Bring these to the relevant qualified professional, manufacturer or authority. Requirements vary by project and location.
- Who has specified the tie type and arrangement for this wall?
- What material are these ties made from, and why that material here?
- How will the cavity be kept clear of mortar droppings during construction?
- In this older building, have the existing ties been surveyed?
- Is the cracking we can see consistent with tie corrosion, or with something else?
- If remedial ties are needed, what caused the originals to fail?
- How are the ties arranged around openings and at the ends of walls?
Blind spots
Commonly overlooked points
- Ties are structural components hidden in a joint, and their arrangement is a design output rather than a site decision.
- A tie bedded properly at one end and poorly at the other does not do the job it was put there to do.
- Corroding ties announce themselves through cracking in the mortar joints long before anything else is obvious.
- Mortar droppings sitting on ties are a common and entirely avoidable route for moisture across a cavity.
- Insulation retaining clips have to suit both the tie and the insulation, and mismatches are surprisingly common.
What this page does not do
- The type, material and arrangement of wall ties are engineering decisions for a qualified professional and cannot be taken from a reference page.
- No statement here should be read as confirming that any wall is adequately tied or structurally sound.
- Suspected tie failure in an existing building calls for a survey by someone qualified to carry one out.
- Requirements vary by location and by building type, and must be confirmed locally before work is planned.
Related entries
Related materials
Materials from the same family, an adjacent role in the assembly, or a shared application.
Inspiration
Related Ideas Library pages
Design directions where this material commonly appears.
Preparation
Related planning checklists
Owner-side preparation before the conversation where this material comes up.
Go deeper
Related Build Design Hub guides
Planning guidance and neutral comparisons behind the decisions on this page.
Masonry & Block Materials
Reference entries for unit masonry — clay and concrete bricks, blockwork, mortars, and the ties, lintels and accessories that hold masonry construction together.
Browse all masonry & blocks entries →