Cast iron
The term 'cast iron' refers to a range of iron-carbon alloys, with a carbon content that is typically between 2 and 4%. During the Industrial Revolution, before the widespread development of the steel industry, cast iron was commonly used in a wide range of architectural applications because of to its relative affordability.
Cast iron is manufactured by re-melting pig iron along with quantities of limestone, silicon and carbon (and sometimes scrap steel). Traditionally, cast iron is melted in a blast furnace known as a cupola, but it can also melted in electric induction furnaces or arc furnaces. The molten cast iron is then poured into a holding furnace or ladle ready for casting (that is, being poured into a mould, and allowed to cool).
The advantages of using cast iron derive from its relatively low melting temperature, which increases its usability, and its good compression strength. However, it is weak in tension and bending, and will fracture before it bends or distorts. It also loses strength and stiffness when subjected to high heat.
In comparison with wrought iron or steel, cast iron is non-malleable, hard and brittle.
[edit] Related articles on Designing Buildings
- Aluminium.
- Conservation of Architectural Ironwork.
- Copper.
- Difference between cast iron and wrought iron.
- Failure of cast iron beams.
- Ferrous.
- Galvanised steel.
- Investment casting.
- Iron.
- Ironwork.
- Metal.
- Metal fabrication.
- Stainless steel.
- Stove.
- Structural steelwork.
- The Iron Bridge.
- Types of metal.
- Weathering steel.
- Wrought iron.
- Zinc
Featured articles and news
Future Homes Standard Essentials launched
Future Homes Hub launches new campaign to help the homebuilding sector prepare for the implementation of new building standards.
Building Safety recap February, 2026
Our regular run-down of key building safety related events of the month.
Planning reform: draft NPPF and industry responses.
Last chance to comment on proposed changes to the NPPF.
A Regency palace of colour and sensation. Book review.
Delayed, derailed and devalued
How the UK’s planning crisis is undermining British manufacturing.
How much does it cost to build a house?
A brief run down of key considerations from a London based practice.
The need for a National construction careers campaign
Highlighted by CIOB to cut unemployment, reduce skills gap and deliver on housing and infrastructure ambitions.
AI-Driven automation; reducing time, enhancing compliance
Sustainability; not just compliance but rethinking design, material selection, and the supply chains to support them.
Climate Resilience and Adaptation In the Built Environment
New CIOB Technical Information Sheet by Colin Booth, Professor of Smart and Sustainable Infrastructure.
Turning Enquiries into Profitable Construction Projects
Founder of Develop Coaching and author of Building Your Future; Greg Wilkes shares his insights.
IHBC Signpost: Poetry from concrete
Scotland’s fascinating historic concrete and brutalist architecture with the Engine Shed.
Demonstrating that apprenticeships work for business, people and Scotland’s economy.
Scottish parents prioritise construction and apprenticeships
CIOB data released for Scottish Apprenticeship Week shows construction as top potential career path.
From a Green to a White Paper and the proposal of a General Safety Requirement for construction products.
Creativity, conservation and craft at Barley Studio. Book review.
The challenge as PFI agreements come to an end
How construction deals with inherited assets built under long-term contracts.
Skills plan for engineering and building services
Comprehensive industry report highlights persistent skills challenges across the sector.
Choosing the right design team for a D&B Contract
An architect explains the nature and needs of working within this common procurement route.
Statement from the Interim Chief Construction Advisor
Thouria Istephan; Architect and inquiry panel member outlines ongoing work, priorities and next steps.