You may have come across a recent BBC news item about a house collapse in London following basement renovation work.
The property was thought to be worth in the region of £1 million and collapsed in the early hours of 3 April 2017.
(Picture on the left courtesy of the Kingston building control team.)
A building regulations application had only been submitted a few days previously and the building control team had not been given the opportunity to offer guidance or approval to this complex area of work.
Sadly this is not the first house collapse incident and it won’t be the last.
A similar house collapse at a property in Barnes, South West London in 2015 also followed basement excavation work, and in 2012 a property in Finchley, also undergoing a basement extension, collapsed with the owners only escaping serious injury by minutes.
Whilst this is the worst case scenario, other issues like cracking and misalignment of doors and windows due to minor subsidence can be frustrating.
As popularity in basement conversions continues to increase, the importance of using a competent builder following an approved sequence of works is critical.
Undermining an existing structure requires careful consideration and planning to ensure that the loads carried continue to be fully supported and transferred back to the ground correctly.
Help is at hand: ASUC
The Association of Specialist Underpinning Contractors (ASUC) offer access, guidance and insurance backed guarantees to accredited members. It is an independent trade association originally formed by a number of leading contractors to promote professional and technical competence within the subsidence industry.
Membership has now been extended to include a comprehensive range of specialist domestic services in underpinning and subsidence repair techniques, engineered foundation solutions and retrofit basement construction.
View and download their Scheme Guarantees leaflet: http://www.asuc.org.uk/pdf_word/ASUC_guarantee_leaflet_2017.pdf
LABC in collaboration with LABC Warranty have put together a technical guide on basement design. View and download Better basements: design and construction technical guide.