I'd advise talking to your neighbor about it. On a daily basis, we argue with planning authorities about this predicament. It is common practice to build an expansion all the way up to the boundary line between you and your neighbor. This extension might be used as a garage, another house, a play area for children, you name it. In most countries, building regulations require you to get permission from your neighbor if you want to extend your house. The reason for this is that buildings can cause damage to their surrounding environment. For example, they can attract birds which may attack other animals or carry diseases. Attracting birds is also dangerous for people because they may come into contact with infectious agents such as bacteria or viruses. Countries have adopted different policies regarding extensions; some allow them everywhere while others allow them only in certain areas. Extensions can be a good thing for you if you need more space or if your house is too small for today's living standards. If you do want to build an extension, make sure you talk to your neighbors first and get their approval. In some cases, they may even help you out by giving you access to their parking space when you need it. Extensions can also be a bad thing if they affect the environment negatively.