Failure of cast iron beams
Many buildings utilising cast iron (CI) continue to give good service with adequate reliability when used in a risk assessed manner and current best practice documents. As is normal with this type of beam, there is rarely any apparent warning of imminent collapse.
Certain combinations of actions may lead to an unsafe situation that should be investigated by a competent structural engineer. These situations include:
- Additional loading on a CI beam, typically arising from further deadweight added since original completion. The unregulated increase of load on a structure should always be a matter of concern.
- Long-standing ingress of water leading to corrosion, deterioration of the concrete infill, and loss of any composite action. Extended basements or roof garden arrangements are particularly prone to this action.
- The beams working at high levels of stress as originally installed. This is more likely in a domestic structure where the beam may have been sized by rule of thumb.
Professionals working in this field, or with clients responsible for property of this type and era, should be aware of these issues and be ready to advise the relevant parties of the need for a structural risk assessment if the identified conditions exist.
[edit] Related articles on Designing Buildings Wiki
- Brittle fracture.
- Cast iron.
- Conservation of Architectural Ironwork.
- Defects in construction.
- Degradation of construction materials.
- Failure of metals.
- Flat roof defects.
- Girder.
- Graphitisation.
- Iron.
- Metal.
- Roofing defects.
- Rust.
- Structural failures.
- Structural steelwork.
- Tension.
- Weathering steel.
Featured articles and news
CIOB Apprentice of the Year 2025/26
Construction apprentice from Lincoln Mia Owen wins this years title.
Insulation solutions with less waste for a circular economy
Rob Firman, Technical and Specification Manager, Polyfoam XPS explains.
Recycled waste plastic in construction
Hierarchy, prevention to disposal, plastic types and approaches.
UK Net Zero Carbon Buildings Standard V1 published
Free-to-access technical standard to enable robust proof of a decarbonising built environment.
Prostate Cancer Awareness Month
Why talking about prostate cancer matters in construction.
The Architectural Technology podcast: Where it's AT
Catch up for free, subscribe and share with your network.
The Association of Consultant Architects recap
A reintroduction and recap of ACA President; Patrick Inglis' Autumn update.
The Home Energy Model and its wrappers
From SAP to HEM, EPC for MEES and FHS assessment wrappers.
Future Homes Standard Essentials launched
Future Homes Hub launches new campaign to help 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.