If so, you may need to submit a planning application for a change of use. If you are unsure, you can apply to the local council for a Certificate of Proposed Lawful Use or Development for your proposed activity to ensure that it is legal. There are several useful links on the Planning Portal. This includes a form that you can download and fill in, which will make the application process easier. You will need to plan your house changing project carefully and make sure that it is allowed before you start work. If you want some advice on what changes could be legally accepted in an existing home, contact an architect or engineer. They will be able to tell you if there are any problems with your plan and help suggest alternatives if necessary. Your new use should be compatible with the character of your area. For example, if you live in a quiet residential street, a nightclub might not be the best use for your house. You would need to get permission from your local council to convert your house into a nightclub. House parties are very common and usually not illegal if they are not being used for commercial purposes. However, this would be an illegal use of your house if it was hosted on more than one occasion per year without the owner's consent. Also, if you charge people to come into your house party, this would be illegal ticket selling.