COR-TEN® weathering steel · Suitability · Detailing
Before you specify COR-TEN®.
COR-TEN® performs best in the right environment, detailed correctly. This guide covers the key considerations before ordering or specifying weathering steel.
Exposure conditions
It works when it can weather.
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 dry between rain events.
- 01
Wet / dry cycles
The surface should get wet and then dry out. Constant dampness can stop the patina stabilising.
- 02
Drainage
Avoid trapped water, ponding, enclosed cavities and areas where moisture sits against the steel.
- 03
Airflow
Ventilation helps the surface dry between wet periods, supporting a more stable weathered layer.
- 04
Run-off
Early weathering releases rust-coloured run-off. This is normal, but plan for it around surrounding finishes.
Run-off staining
Plan for rust-coloured run-off.
Run-off is strongest during early weathering, before the patina matures. Water running off COR-TEN® can mark paving, concrete, render, stone, glass and light-coloured finishes below.
Good practice
- Use drip edges to control where water leaves the panel or feature
- Allow for drainage so water doesn't sit behind or under the steel
- Consider darker finishes below, or areas where marking won't matter
Avoid
- Uncontrolled run-off over white render, pale concrete, stone or finished paving
- Details where water is trapped against the steel for long periods
- Assuming COR-TEN® will behave like a painted or sealed metal
Suitability guide
Where COR-TEN® performs best.
COR-TEN® suits exposed architectural and landscape applications where the steel can weather, drain and dry correctly. The environment, detailing and surfaces below all need considering.
Best suited to
- External claddingFacades, wall panels and architectural cladding exposed to natural weathering.
- Open-air detailsScreens, feature panels and folded elements with airflow around the material.
- Landscape featuresPlanters, edging and retaining features where drainage and staining are considered.
Use caution around
- Constant moistureAreas where the steel stays damp, traps water or can't dry properly.
- Coastal exposureHigh-salt environments can affect weathering and may need project-specific assessment.
- Light surfaces belowEarly run-off may stain concrete, stone, paving, render or other light finishes.
Service life & conditions
Longevity is project-specific.
COR-TEN® can provide a long service life when detailed and used correctly, but it doesn't have one fixed lifespan. Performance depends on environment, exposure, drainage, fixing method, corrosion allowance and surrounding conditions. Coastal, salt-heavy, industrial, constantly damp or poorly ventilated sites may need project-specific assessment.
Material supply only
Corten Australia supplies raw COR-TEN® sheets and coils. We don't provide project design, certification, fixing design or installation advice.
Project suitability, detailing, fixing, drainage, engineering and installation should be confirmed by the buyer, fabricator, builder, architect or project team before ordering.
Specified and ready to order?
Request a quote.
Send through your product, thickness, quantity and delivery location, and we'll confirm stock, pricing, freight and lead time.