Before You
Specify
COR-TEN®.
COR-TEN® performs best when it is used in the right environment and detailed correctly. This guide covers the key design considerations around wet and dry cycles, drainage, run-off staining, coastal exposure and unsuitable conditions before ordering or specifying weathering steel.
It Works When
It Can Weather.
COR-TEN® is designed to form a protective patina, but that patina depends on the right exposure conditions. Unlike painted or coated steel, COR-TEN® relies on natural weathering. The surface needs alternating wet and dry cycles, with enough airflow and drainage to allow the material to dry between rain events.
Wet / Dry Cycles
The surface should be able to get wet and then dry out. Constant dampness can stop the patina from stabilising properly.
Drainage
Details should avoid trapped water, ponding, enclosed cavities and areas where moisture sits against the steel.
Airflow
Ventilation helps the surface dry between wet periods, supporting the development of a more stable weathered layer.
Run-Off
Early weathering can release rust-coloured run-off. This is normal but should be planned for around surrounding finishes.
Plan For
Rust-Coloured Run-Off.
During early weathering, run-off risk is strongest before the patina has matured. Water running off COR-TEN® may mark paving, concrete, render, stone, glass and light-coloured finishes underneath.
Good Practice
- Use drip edges to control where water leaves the panel or feature.
- Allow for drainage so water does not sit behind or under the steel.
- Consider darker finishes below, or areas where natural marking will not be an issue.
Avoid Issues
- Avoid uncontrolled run-off over white render, pale concrete, stone or finished paving.
- Avoid details where water is trapped against the steel for long periods.
- Avoid assuming COR-TEN® will behave like a painted or sealed metal surface.
Where COR-TEN®
Performs Best.
COR-TEN® is well suited to exposed architectural and landscape applications, but it should be used where the steel can weather, drain and dry correctly. The surrounding environment, detailing and surface below all need to be considered.
Best Suited To
External Cladding
Facades, wall panels and architectural cladding where the surface is exposed to natural weathering.
Open Air Details
Screens, feature panels, folded elements and exposed details with airflow around the material.
Landscape Features
Planters, edging, retaining features and outdoor elements where drainage and staining are considered.
Use Caution Around
Constant Moisture
Areas where the steel stays damp, traps water, sits against wet surfaces or cannot dry properly.
Coastal Exposure
High-salt environments can affect weathering performance and may require project-specific assessment.
Light Surfaces Below
Run-off during early weathering may stain concrete, stone, paving, render or other light-coloured finishes.
Longevity Is
Project-Specific.
COR-TEN® can provide long service life when detailed and used correctly, but performance depends on the project environment, exposure, drainage, fixing method, corrosion allowance and surrounding conditions.
Long Service Life,
When Used Correctly.
COR-TEN® should not be treated as having one fixed lifespan for every project. Coastal, salt-heavy, industrial, constantly damp or poorly ventilated environments may require project-specific assessment before the material is selected or installed.
Project-Specific Performance
Service life depends on site conditions, exposure, drainage, detailing and installation. These factors should be reviewed for each project before use.
Supply Only
Corten Australia supplies raw COR-TEN® sheets and coils only. We do not provide project design, certification, fixing design or installation advice.
Confirm Suitability With
Your Project Team.
Corten Australia supplies genuine SSAB COR-TEN® sheets and coils in bulk. Project suitability, detailing, fixing, drainage, engineering and installation should be confirmed by the buyer, fabricator, builder, architect or project team before ordering.