How can you tell how deep your neighbours' foundations are re Party Wall Act?

[DaisymooSteiner]

We're planning an extension which will be within 3 metres of our neighbours' house and apparently we will need to serve notice under the Party Wall Act if our foundations will be deeper than theirs. How can we tell? It's not a very old house, maybe 30 years old or so.

TIA.

hi. not sure about your question, but we've just been through it all with our neighbour and found this a really informative read, includes sample letters for you to use, saving a fortune on surveyors fees!

www.planningportal.gov.uk/uploads/br/BR_partywall_explain_booklet.pdf

What's your question Hothead? How old is your neighbour's house?

DH is a surveyor and deals with Party wall issues, he has typed this out.

If their wall is on the boundary you could excavate a small trial Pitt by hand. If built from the mid 1980's onwards the local authority building control department may have details. If older probably safe to work on the presumption that their foundations will likely be shallower than yours and hence require notice.

Alternatively you may be able to use a reinforced raft or a cantilevered foundation design to avoid the need for notice.