When a basement extension goes wrong...

Blog Post
Basement extension collapse Kensington

A basement extension can be a great way to add living space, a new, bedroom, games room, office or gym, for example. The attached photos sent to us by an LABC member show what can go wrong.

This started life as an expensive basement extension in Knightsbridge, London:

Basement extension collapse Kensington

The owner had followed the correct protocol in hiring a structural engineer to create a plan for the underpinning of the structure, the purpose of which was to ensure that this crucial work was done in the right sequence.

However an over-enthusiastic builder decided not to follow the sequencing and as a consequence the clay soil rotated or shifted, leading to a total collapse of the rear extension above the intended extension.

Basement extension collapse Kensington

Thankfully nobody was hurt in this instance, but it did lead to a complete rebuilding of the rear extension.

The lesson learned? On the part of the builder, the importance of following the correct sequence as laid out by a qualified structural engineer, and for the homeowner, choose the people you work with on your home improvement project as carefully as possible (following our advice below).

Further information

How to avoid cowboy builders (and how LABC can help)


Basement project

Submitted 3 mis ago

Highlights the need for a competent contractor in the team to. Choose from audited contractors www.asuc.org.uk

Steel Beam RSJ Structural Calculations

Submitted 2 mis ago

Please take extra care to avoid these accidents. I took professional advice, not just on the design side, but also help with safe construction.
Steel Beam Calculations for Building Control Approval. We design all Structural elements and advise or consult on the structural fundamentals of your extension or property development. We have over 30 years’ experience at www.onlinebeam.co.uk producing full Structural Design Packages from Surrey. We design steel beams or RSJ’s with full Structural Calculations for loft conversions, load bearing wall removal, extensions and commercial projects.

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