Hi, I have planning application to extend the property at the back. We already have a common wall extension with my neighbour and I am extending that extension bit further. The plan was to build only on my side of the border in the middle of the wall. Our building regulation drawings show that. My neighbour decided that they may want to extend their side soon, so now they asked me if I could build on their side, so the extension wall is bang in the middle so they can use my wall as part of their extension in the near future. Do I need a new planning application (2 month job) or we are covered by the existing party wall act regulations and they just need to agree on the wall being built astride the border? Thank you for any answers. I am keen to start building works within 4 weeks to take advantage of the good summer weather.