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CROSS Safety Report

Incorrect steel lintel installation

Report ID: 1008 Published: 13 December 2021 Region: CROSS-UK


Overview

A reporter came across several issues, associated with the installation of steel beam lintels, while carrying out inspection works on a 1950’s domestic property.

Key Learning Outcomes

For architects and designers:

  • When there are structural alterations then engage a chartered structural engineer
  • Consider including the structural information on the drawings submitted to building control and to the contractor

For civil and structural engineers:

  • Try to ensure that you are given opportunities to visit sites and ensure that construction is in accordance with the design

For builders and contractors:

  • Do not rely on building control to make site inspections
  • It is the contractor’s duty to ensure that installation of structural steelwork is correct

Full Report

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A reporter inspected the works on a 1950’s domestic property where structural modifications included the removal of supporting walls and installation of steel lintels. A primary beam was spanning the width of the property with a secondary beam projecting perpendicular about a 1/3 of the way along the beam onto existing brickwork.

Fortunately, the visit was made when the steel lintels had just been installed and a number of observations were made: 

  1. The steel beam bearings were inconsistent and not in accordance with the structural engineer's drawings.

  2. A secondary beam had not been bolted to the designated connection. Instead, the secondary beam's bottom flange was sitting simply supported on the top flange of the primary beam.

  3. On one end, the support brickwork under the padstone had been reduced in size.

  4. The packing between the top flange of the primary steel and the existing structure was inconsistently installed.

Remedial measures had to be undertaken including the construction of additional masonry to the deficient padstone and taking measures to increase the lateral torsional stiffness of the beam and connection fixity of the primary and secondary steel beams.

Expert Panel Comments

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Unfortunately, with the boom in domestic property extensions and alterations the quality and skill of the builders appointed is not always assessed and checking of the installation is left to building control even though it is not their role. There may not be a structural engineer involved but in any event, it is the contractor's job to check that the installation is correct. The building inspector checks compliance with the building regulations but is often forced to intervene because the contractor has created a dangerous situation.

It should be clear who is responsible for the design and checking of steelwork connection details.

Indeed contractors may be relying on building control to pick these structural basics up before they are covered in finishes? These issues eat away at factors of safety that may result in dangerous structural damage, well beyond cracking, i.e. the potential for sudden collapse.

If there is an engineer, then on small domestic jobs communication of structural intent may be done through the one drawing likely to be used on site - the architect’s drawing. The engineer should ensure their information is included, not just a note saying; "refer to structural engineer’s details". This drawing should be part of the building control submission.

Quite often the quality of the installation is not discovered until cracking occurs or the next round of alterations are undertaken. It is common to see zig-zag cracking in masonry where beam(s) have been introduced to open up the ground level kitchen space without proper consideration of the deflections that can result.

Quite often the quality of the installation is not discovered until cracking occurs or the next round of alterations are undertaken

CROSS will keep stressing that engineers should be able to check, preferably in person, that the installation is in accordance with their design.

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