Skip to main content

CROSS Safety Report

Collapsed section of dwelling built of cob construction

Report ID: 609 Published: 1 April 2017 Region: CROSS-UK

This report is over 2 years old

Please be aware that it might contain information that is no longer up to date. We keep all reports available for historic reference and as learning aids.


A reporter says that a traditional cottage built of cob construction collapsed without warning in 2016.

Key Learning Outcomes

For construction professionals and designers:

  • Careful consideration is needed for the selection of construction materials and their corrosion protection to ensure they are suitable for the given environment

  • Consider introducing a quality management procedure to ensure construction elements have the correct protection to prevent deterioration

Full Report

Find out more about the Full Report

The Full Report below has been submitted to CROSS and describes the reporter’s experience. The text has been edited for clarity and to ensure anonymity and confidentiality by removing any identifiable details. If you would like to know more about our secure reporting process or submit a report yourself, please visit the reporting to CROSS-UK page.


A reporter says that a traditional cottage built of cob construction collapsed without warning in 2016. From their experience, collapses of cob construction are usually caused by water ingress, but the cause for this collapse is currently unknown as there was dry weather and no recent rainfall.

The reporter speculates that there was a possible loss of lateral support to gable end due to rot in the first floor joists.

Expert Panel Comments

Find out more about the Expert Panels

Expert Panels comment on the reports we receive. They use their experience to help you understand what can be learned from the reports. If you would like to know more, please visit the CROSS-UK Expert Panels page.

Cob, also known as cobb, is a building material that comprises subsoil, straw (or another fibrous organic material), water, and occasionally lime. There is evidence of cob being used for building construction purposes in prehistoric times in various parts of the world and it was used for centuries in the south-west of England. Cob building has experienced something of a revival in recent years as a form of sustainable construction. For more information, see the Designing Buildings Wiki page on cob building.

Submit a report

Your report will make a difference. It will help to create positive change and improve safety.

Our secure and confidential safety reporting system gives professionals the opportunity to share their experiences to help others.