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CROSS Safety Report

Defect on site deliberately covered up

Report ID: 217 Published: 1 January 2011 Region: CROSS-UK

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Overview

A reporter shares an experience they had whilst working for a contractor as an assistant site engineer and provides evidence of the risks associated with the reliance on self-certification of construction.

Key Learning Outcomes

For the construction team:

  • Be aware that durability is a safety issue if the design life of the building is compromised and covering up faults before they are repaired is a serious matter

  • Quality control and competent supervision on site can help to ensure that the structure is built in accordance with the design

Full Report

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A reporter says that supervision of construction has declined over the last 15 to 20 years and believes that the Eurocodes could provide a basis for change. They want to share an experience they had whilst working for a contractor as an assistant site engineer of evidence of the risks associated with the reliance on self-certification of construction.

The site level had to be raised which allowed reinforced concrete pile caps and ground beams to be constructed above ground level. At one end the formwork was struck within a couple of days and fill immediately placed to form the founding layer for the ground slab. During the compaction of the fill, which was done by a subcontractor, part of the ground beam was damaged by a roller. A section of foundation approximately 1.0 m long was broken off, exposing the reinforcement on the internal face of the footing.

The reporter brought this to the attention of the site engineer, agent and project manager separately and was assured that it would be repaired. The repair was never carried out and the fill was brought up to finished level to hide the problem. The damage cannot be seen on the finished structure and the area of damage was not bearing any significant load. The reporter anticipates that the only consequence is a reduction in the durability of the finished structure.

The repair was never carried out and the fill was brought up to finished level to hide the problem.

This problem was the direct responsibility of a subcontractor whose senior staff were aware of the issue. It was not rectified because of the time it would have taken to resolve which would have delayed completion and affected the contractor's profit. This commercial pressure motivated the contractor to hide the problem and has left a less durable structure. This same commercial pressure exists on all contractors and the reporter contends that independent supervision is the most effective mechanism to ensure that structures are constructed to specification.

Expert Panel Comments

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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.

This shows a dereliction of construction standards. Durability is still a safety issue if the design life of the building is compromised and covering up faults before they are repaired is a serious matter. The report reminds us that the quality of a design is only as good as the quality of execution. All building professionals will be aware that things happen on site that were often not envisaged at the design stage, and safety is assured by periodic inspection – this is especially true in conversion work.

Incidents of this type described need a multi-facetted approach: competency, fair tendering, sensible timescales, and targeted supervision on critical elements or stages. As another example one CROSS panel member recalls visiting a site and spotting that the plant room flat slab (300mm thick) had actually been cast using the drawings of the floor below (200mm thick) such that the top rebar had 125mm cover!

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