Galvanised vs Stainless Steel SHS Cleats: Which Is Right for Your Project?
Galvanised vs Stainless Steel SHS Cleats: Which Is Right for Your Project?
Choosing the right material for SHS cleats is an important consideration in Australian construction. Steel connection components must suit the structural requirements of a project while providing appropriate protection against corrosion and environmental exposure.
Two materials often considered for steel connections are galvanised steel and stainless steel. Both offer corrosion resistance, but they achieve it differently and may be suitable for different applications.
For builders, fabricators, engineers and construction professionals, understanding these differences can help with material selection, maintenance planning and long-term project costs.
In this guide, we compare galvanised and stainless steel SHS cleats, explain their key differences and outline the factors to consider when choosing a connection solution.
What Are SHS Cleats?
SHS stands for Square Hollow Section, a type of hollow steel section commonly used for posts and columns in structural frameworks.
SHS cleats are connection components designed to join these posts to other structural members, including timber beams, steel beams, floor bearers and bracing members.
Depending on their purpose, cleats may be used in applications such as:
Timber verandah and roof beam connections.
Timber floor bearer support.
PFC steel beam connections.
Steel angle bracing systems.
Column baseplate connections.
Residential and commercial structural frameworks.
SHS Cleats offers several connection categories, including SHS Timber Beam Cleats, Timber Beam Top Plate Cleats and SHS-PFC Beam Cleats.
The choice of material and protective finish should match the intended application, exposure conditions and engineering specifications.
What Are Galvanised Steel SHS Cleats?
Galvanised steel cleats are generally manufactured from steel protected by a zinc coating. This coating helps protect the underlying steel from corrosion.
Zinc provides a protective barrier and can also offer sacrificial protection at small exposed areas, such as scratches, under suitable conditions.
Galvanised steel is widely used for construction components because it combines the properties of steel with an added layer of corrosion protection.
Advantages of Galvanised Steel Cleats
1. Practical corrosion protection
The zinc coating helps protect the steel from moisture and oxygen. Its performance depends on coating type and thickness, surface condition and environmental exposure.
2. Suitable for many building applications
Galvanised steel may be suitable for numerous residential and commercial construction applications, including appropriately specified external connections.
3. Practical material choice
For many projects, galvanised steel can provide an appropriate balance between corrosion protection, material cost and expected service life.
4. Compatibility with common steel construction
Galvanised steel components are commonly used with structural steel posts, beams and other building components, provided the complete connection is correctly specified.
Limitations of Galvanised Steel
Galvanising does not make steel completely immune to corrosion. The zinc coating gradually wears or corrodes over time, and its service life depends on the environment.
Coastal areas, salt exposure, industrial pollution, persistent moisture and damage to the coating can increase corrosion risk.
Cutting, drilling or welding galvanised components can also affect the protective coating and may require appropriate repair or additional protection. Welding galvanised steel requires suitable controls because heating zinc coatings can generate hazardous fumes.
What Are Stainless Steel SHS Cleats?
Stainless steel contains chromium, which enables the formation of a thin passive surface layer that helps resist corrosion.
Different stainless steel grades offer different levels of corrosion resistance. Grade 304 and grade 316 are common examples, but the appropriate grade depends on the application and environment.
Grade 316 generally provides improved resistance to chloride-related corrosion compared with grade 304, making it a common consideration for demanding marine and coastal environments.
However, stainless steel is not completely corrosion-proof. It can still experience staining, pitting or crevice corrosion under unsuitable conditions.
Advantages of Stainless Steel Cleats
1. Corrosion resistance
Stainless steel can provide excellent corrosion resistance when the grade, finish, design and maintenance arrangements suit the exposure conditions.
2. Reduced reliance on a zinc coating
Unlike galvanised carbon steel, stainless steel relies on its own passive surface layer rather than a separate zinc coating.
3. Potential for long service life
In appropriately selected environments, stainless steel may provide long service life with suitable cleaning and maintenance.
4. Suitability for demanding environments
Selected stainless steel grades can be appropriate for coastal, marine or industrial applications where ordinary galvanised steel may require more frequent maintenance or a different protection strategy.
Limitations of Stainless Steel
Stainless steel may have a higher initial material cost than galvanised steel, although the difference depends on the grade, product design, fabrication and market conditions.
Its performance also depends on proper detailing. Trapped moisture, salt deposits, surface contamination and unsuitable contact with other metals can cause problems.
Stainless steel components must still be designed for the required structural loads. Corrosion resistance alone does not establish whether a cleat is structurally suitable.
Galvanised vs Stainless Steel SHS Cleats: Key Differences
These are general comparisons. Actual performance depends on the specific material, manufacturing process, connection design and installation environment.
The Australian Stainless Steel Development Association provides further information in its comparison of stainless steel and galvanised steel.
Which Material Is Better for Outdoor SHS Cleats?
The answer depends on where and how the connection will be used.
1. Inland Residential Projects
For many inland residential projects with ordinary atmospheric exposure, appropriately specified galvanised steel may provide suitable corrosion protection.
The decision should consider whether the cleat is exposed to rain, sheltered beneath a roof, close to the ground or subject to persistent moisture.
2. Coastal Construction
Coastal locations can expose steel components to airborne salt and chloride deposits. These conditions can accelerate corrosion and influence the required material specification.
An appropriately selected stainless steel grade, such as grade 316 in suitable applications, may be worth considering. However, galvanised steel may also be suitable in some coastal conditions when the protection system is correctly specified.
The distance from the coast alone is not enough to determine the right material. Local exposure, shelter, wetting, salt accumulation and maintenance access also matter.
3. Commercial and Industrial Buildings
Commercial and industrial projects may involve different exposure conditions, including chemical contaminants, condensation or frequent cleaning.
The material should be selected according to the actual environment and the design life required. A corrosion assessment may be appropriate where exposure conditions are aggressive or uncertain.
4. Covered Outdoor Structures
Verandahs, pergolas and covered outdoor structures may experience less direct weather exposure than fully exposed connections. However, wind-driven rain, condensation and coastal salt can still affect the components.
Consider the actual location of the cleat rather than assuming that a covered structure is automatically a low-corrosion environment.
Can Galvanised and Stainless Steel Be Used Together?
Galvanised and stainless steel components can be used together in some applications, but the connection needs careful consideration.
When dissimilar metals are electrically connected and exposed to moisture or another conductive liquid, galvanic corrosion may occur. In a galvanised-steel and stainless-steel connection, the zinc coating may corrode more rapidly under certain conditions.
The level of risk depends on factors such as moisture, salt contamination, the relative exposed surface areas of the metals and the connection details.
Where required, suitable insulating washers, barriers or other isolation measures may help reduce the risk. These measures must be compatible with the structural connection and must not compromise its performance.
Read the Australian Stainless Steel Development Association's guide to galvanic corrosion for more information.
How to Choose the Right SHS Cleat Material
Before selecting galvanised or stainless steel cleats, consider the following factors:
Environmental exposure: Identify whether the connection is indoors, outdoors, coastal or exposed to industrial contaminants.
Required service life: Consider the intended design life and the maintenance that can reasonably be provided.
Structural requirements: Confirm the connection's loads, geometry, fasteners, welds and material specifications.
Compatibility: Check contact between different metals, including bolts, washers, posts and connected members.
Fabrication requirements: Consider cutting, drilling, welding and the appropriate treatment of affected surfaces.
Whole-of-life cost: Compare initial purchase price with maintenance, inspection, replacement and expected service life.
Product availability: Confirm that the selected configuration and material are available and suitable for the intended application.
For timber floor bearer connections, explore the SHS Timber Beam Top Plate Cleats. For column support applications, review the SHS Baseplates, Top Plates and Single Cleats range.
Always confirm the final specification against the manufacturer's documentation, project engineering requirements and applicable Australian Standards.
Frequently Asked Questions
Are galvanised steel SHS cleats suitable for outdoor use?
They can be suitable for many outdoor applications when the galvanising system and connection details are appropriate for the environmental exposure. More aggressive conditions may require additional protection or another material.
Is stainless steel always better than galvanised steel?
No. Stainless steel can offer advantages in demanding corrosive environments, but the correct choice depends on exposure, grade, cost, structural requirements and maintenance. Galvanised steel may be a practical option for many applications.
Which stainless steel grade should I consider near the coast?
Grade 316 is commonly considered for chloride-rich environments, but the appropriate grade depends on the severity of exposure, surface finish, design and maintenance arrangements. Obtain project-specific advice where necessary.
Can stainless steel cleats rust?
Stainless steel can develop surface staining and localised corrosion under certain conditions. Selecting a suitable grade, preventing contamination and maintaining the surface help manage this risk.
Does the material affect the strength of an SHS cleat?
Yes, material properties can affect structural design, but neither galvanised nor stainless steel is automatically stronger in every application. The grade, dimensions, connection geometry, fasteners and welds must all be considered.
Conclusion
Both galvanised and stainless steel SHS cleats can be useful in Australian construction, but they serve different material-selection needs.
Galvanised steel offers a zinc coating that can provide practical corrosion protection for many building applications. Stainless steel may offer improved corrosion resistance in demanding environments when the correct grade and finish are selected.
The best choice depends on the project's exposure conditions, design requirements, expected service life and maintenance plan. Rather than selecting a material based on price or appearance alone, assess the complete connection and confirm its suitability with the relevant engineering documentation.
Explore the SHS Cleats product range to review available steel connection configurations for your next project.
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