- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 07 Jun 2017
Weathering steel (also known by the trademark COR-TEN steel) is a form of high-strength, low alloy steel originally developed in the 1930's by United States Steel. It is a steel alloy, chemically composed to form a stable rust-like appearance that can resist corrosion and abrasion, by forming a protective surface layer, or patina.
The protective layer’s increased resistance is produced by the alloying elements and their particular distribution and concentration. When subjected to the influence of the weather, the protective surface layer continuously develops and regenerates, allowing the rust to form.
Weathering steel is often used in external sculptures, the most iconic of which is the Angel of the North in Gateshead. It can be used in bridges and other large structural applications, such as the New River Gorge Bridge, and it is becoming an increasingly popular design choice for buildings, often used alongside materials such as glass and terracotta. An example of such a building is the distinctive Broadcasting Tower in Leeds (see top image).
The advantages of weathering steel are that because it is already weathered and ‘rusted’, there are very low maintenance costs, it can be installed easily, and the need for a protective paint system is removed. Studies have found that bridges fabricated from unpainted weathering steel can achieve a design life of 120 years with only nominal maintenance, due to the low corrosion rate.
However, there are several challenges to weathering steel. It is unsuitable for use in marine or coastal environments, and in humid subtropical climates the patina may continue to corrode instead of stabilising into a protective layer. In addition, interface details require careful design as run-off water from wet rusted steel may negatively impact on other materials, such as staining glass. This is a particular problem in the first years after installation.
 Find out more
 Related articles on Designing Buildings Wiki
Featured articles and news
Brokenshire launches an implementation plan for the recommendations made by Dame Judith Hackitt.
BSRIA publication provides guidance about the capture and analysis of big data.
Gove launches a waste and resources strategy for England.
Only 9% of construction workers are 24 or younger.
Blighting local areas, preventing investment and and encouraging anti-social behaviour.
Sharing knowledge about the conservation of the built and historic environment.
CIOB launches a call to improve quality in the built environment.
Vastint gets permission for a 6.6 hectare site to support the expansion of Leeds’ city core.
One of the Isle of Man’s best 1960s buildings.
Using renewable energy in developing countries - QSAND and Loughborough University Research collaboration.
From frost damage to sulphate attack, common causes of defects in brickwork.