What is the Party Wall Act 3 metre rule?


The Party Wall act covers excavations within 3 metres of an Adjoining Owner, if the lowest point of the excavation will be lower than the underside of the footings to the party wall (or parts of their property which are within three metres of the proposed excavation).

Therefore, if the proposed excavation will exceed the depth of any existing footings, then a Notice will need to be served, by the legal owner of the land who is instigating the building works.

In order to be valid, a ‘Three Metre’ Notice will also need to include a section drawing, showing the depth of the new excavations proposed, and its position relative to pre – existing property.

Experienced party wall Surveyors will make a reasoned assumption about the depth of the existing foundations to a property, based on its date of construction, and other factors.

In some instances, a trial pit is dug, to ascertain the existing foundations, but this may be carried out to verify design assumptions, once the party wall process is further forward.


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At Harding Chartered Surveyors, we’re a team of independent and impartial RICS surveyors that can carry out party wall matters. If you have any questions or need advice don’t hesitate to call us on 020 3598 6730.

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