The Need to Serve Notice when Extending Height of Perimeter Walls to Existing Extension

by: The Party Wall Surveyor


We have a  bathroom extension built a number of years ago to our property. We are proposing to convert this space to a garden room with a large opening in the back wall and bi-fold doors. We would like to change the roof detail to a parapet with aluminium coping to give a more contemporary feel. This involves building on extending the height of the perimeter walls. Do we need party wall approval?

We think the existing wall sits entirely within our property. Our neighbours have a lean to shed which is flashed into the wall. Their shed is in a state of disrepair and falling apart. They may well want to take the shed down.


Whether the work is notifiable to your neigbour depends on the status of the flank wall to your extension. If it is built entirely on your own land then no notice is required (Section 1 of the Act only applies for new walls built on the line of junction not walls built on top of existing walls) but if it is a party wall i.e. built astride the boundary, you would have to serve notice under Section 2(2)(a). 

If there was a party wall award relating to the original building of the extension that may provide details on the status of the wall but if not it will just be a case of checking its position in relation to the boundary.


I am sure that the wall is within our site boundary. So difficult to tell as the existing fence is falling apart. My obvious preference would be to avoid the need for a party wall agreement. I have spoken to our neighbours and they are happy. Is that a reasonable approach? – The builder starts next week!


It sounds reasonable to me. There are no penalties for not complying with the Act – the only risk is that the adjoining owner will apply for an injunction to stop the work but if they are happy that is not going to happen.