Hello, I’m hoping that someone might be able to clarify a situation for me, I share a boundary wall with my neighbours. My previous neighbours built an extension right up to the garden/ boundary wall over thirty years ago, and before I bought my house. My current neighbours have increased the height of This extension by approximately 30/50cm over the course of the last couple of years, the roof leaks, and rather than start from scratch, they do patch up jobs, but never really fix the problem. They have now installed an extractor fan, which blows into my garden, and if my back door is open, the odors come blowing in, I’ve asked them to fit a longer pipe and point it skywards, rather than horizontally as it is now, but this would contaminate their washing which they have drying on washing lines( yes lines, 4 in total)on said extension roof, which I suspect is the cause of the leaks. Do they need planning permission for this, or will they just apply for retention when works are complete?