The construction codes must be followed for any home additions. The integrity of the building's construction, including its base, window and door openings, lintels, beams, and roof structures, is obviously a concern. Therefore, as part of your application for building rules, your design must typically include the calculations of a structural engineer. Here you can get a complete Guide to Building an Extension, These calculations must also be presented with the drawings. You have two options for submitting your application: either through the building control department of your local government or through a private company of authorised inspectors. There are two ways to submit an application, full plans or the streamlined process known as a building notice. Before you begin construction on a significant project like an extension, it pays sense to get your design certified by the former. Otherwise, if your project doesn't adhere to the standards, you risk getting into difficulty.