In a recent article in the RICS Modus Magazine, “Does it make sense to build below ground”, Roxane McMeeken weighed up the pros and cons of developing below ground. The main arguments included various hazards that have to be taken into consideration when building down. One particular point she made involved an old church at the end of the street with shallow foundations, stating that “your activity underground could shake it severely”. In fact any adjacent property could be adversely affected by a basement development. With this in mind if you are considering excavating for a basement conversion then you should consider the Party Wall etc. Act 1996.
If the adjoining owner’s property is within 3m of your development, then you will more than likely have to serve a Section 6 Notice on the adjoining owner as your excavations for the basement will probably go below their existing foundations. Additionally, if the design of the basement requires reinforced concrete to be placed on the neighbour’s land then under Section 7(4) you cannot do so without written consent from the Adjoining owner. If the Adjoining owner does not consent, then this could add time and costs to the build as the design will need to be changed.
Developing a basement could also involve cutting in to the existing party wall to place bearing beams or even building a new party wall astride or up to a line of junction. All of which will require you as the Building Owner to serve Notice on the neighbours affected.
Any works involving a basement conversion could adversely affect the adjoining owner’s property. As the Party Wall Act has a unique dispute resolution mechanism it deals very well with the structural design and execution of the works. Invoking the Party Wall Act can protect both the Building Owner and the Adjoining owner by initially ensuring that best practices are followed to a high standard and then should any damage occur, by compensating the affected party.