My Neighbour & I Are Both Planning to Extend

by: The Party Wall Surveyor


I have a property (call it #44). There is a detached brick built garage on the property that 100mm away from its boundary with its neighbour (#42). The nearest part of any building on #42 is 4m+ away. I intend to demolish the garage and enlarge my house with a single story extension. The extension will be further from the boundary (minimum 1.2m). I had looked into the act and felt that there was no need to serve notice on the neighbour. The new owner of the neighbouring property (#42) knowing my intensions (PP granted) has now secured PP to add a single story extension to his house. It will be 100mm from the boundary (boundary fence is mine). He has started the work clearing the way to excavate his foundations. He has not invoked the party wall act by serving notice on me.

I am trying to get my head around which part of the Act applies. His new foundations will be alongside the boundary fence (possibly damaging the concrete Fence fixings. They will also be less than 200mm from the foundations of my garage and will certainly be deeper than my garage foundations. However he does know that I intend to demolish said garage so who knows what he is thinking.  He is the most obnoxious man I have ever met and impossible to reason with. I would like to suggest that if he could wait a couple of weeks I could dig the new foundations for my extension at the same time as he does his and we won’t need surveyors etc. but that would be impossible.

My dilemma is that because any damage to my building would be of no consequence it seems useless for me to ask for the excavation to be postponed for the notice period. However I am concerned that when I excavate my foundations (unless I ensure they are no lower than his new foundations) he will hit me with the party wall act…even though he may be no further ahead of me than having laid his foundations.


From your question you appear to have a good understanding of the Act.

Your neighbour’s work would come within the scope of the act as your garage is classed as a structure and he will be excavating close to and deeper than its foundations. As you say – it would be pointless to insist on a notice if it is to be demolished. If he is excavating within 3 metres of your house that would be another matter…

Regarding your own works – the foundations of the 2 extensions are likely to be the same depth – if that is the case you would not have to serve notice. What would change that position is if the land was sloping towards you or if there were any trees closer to your foundations than your neighbour’s. If you are not going any deeper than the foundations to your neighbour’s extension then you need only concern yourself with the foundations to the original part of his property but only if you are within 3 metres. Bear in mind that it is the distance from adjoining structures, rather than boundaries, that is important.

My neighbours contractor started excavating today. Although the neighbour is very unpleasant I made the decision to get on with the builder and got him to tell me the depth of his foundations. Our land slopes downwards towards his and our land is about 100mm higher where we will dig than the level of land where he will dig.

I agree with your comments and will only inform him if there is a ground issue which causes us to have to dig deeper than normal (most unlikely). Then if he objects he can always go and get an injunction to stop the work and we will see how seriously the courts take the word of a hypocrite.