Party Wall Act

[haydnp]

My neighbour and I share a party wall (the side of their house which is on our land). I wish to either build a single story extension up to the party wall (so the wall is the outer skin), or either within a foot of it. Our houses are 150+ years old. Afaik, if building within 3m of a neighbouring property, the new footings cannot be deeper than the existing. Modern foundation footings for a single story are meant to be at least 200mm deep. As our house was built pre 1878 Building Act which first specified footing depths, I am wondering what the existing footings may be (I know a structural surveyor will be able to say definitively). Does anyone know what the approximate footings were for buildings pre 1878? Its a 3 story terrace. Sorry for such a specific question.

They varied on circumstances but were generally much less than modern day requirements. Are they no other houses with similar extensions that you can view on the council planning portal?

Building Control will give advice based on the soil type and height of any new build.

You will need advice definitely but start by talking to Building Control.

Some houses that age had very little foundations so there could be some risk building and digging deep. There is another thread in here where a house has cracking and a suggestion it is differential movement?

Talk a lot to your neighbour and cross your fingers they cooperate and you will potentially need a party wall,agreement, especially if connecting to their house

Our minimum foundations for an extension were set at 1 metre? As it happened they dug down 2.1M so a hell of a lot of concrete went in