Choose homestyle uk to be your extension builder, from alterations big or small to house extensions to suit all budgets. Making your house. There are currently sixteen parts (sections) to the building regulations (E & W) and each is lettered as Part A to Part Q (however there is no Part I or N) accompanied by an approved document for that Part X. The approved documents usually take the form of firstly stating the legislation and then providing a number of methods or ways which are deemed to satisfy the regulations.