Planning Process
There are two main applications required by your Local Authority: planning and building control.
Planning
The first is Planning Permission, which mainly deals with the outward appearance of the works, including size and materials. On a basic level, if your works fall into the category of Permitted Development, you can submit a Lawful Development Certificate application. If your works do not fall into this category, you should apply for Planning Permission. The council charge around £230 for either of these applications. The council also require an OS Location Plan as part of the submission, which typically costs around £30.
Building Control
The second is Building Control, which is mainly concerned with quality and safety of the construction. For small projects, you can submit a Building Notice. This is a declaration to your Local Authority that you will comply with Building Regulations without submitting full details of how you will construct. The fee for a Building Notice varies with each Local Authority and depends on how much work you do, but is usually around £400 - £700 for a small extension.
Programme
Once a design has been agreed upon, it usually takes around three to four weeks to produce the information for the planning application and once submitted to the Local Authority, eight to ten weeks for the decision. It usually takes around two to three weeks to produce the information for the Building Notice and once submitted, two to three days before you can start work.
Information is correct at time of publishing