How long does it take to get approval?
If your conversion is minor and carries no detailed plans, it means there will be nothing to inspect and approve. All you need is to give notice, typically 48 hours before commencement of the project. Once your notice is accepted, you can start work.
But in the event that you have elaborate plans that have to be thoroughly examined before approval is given, it may take some time. By law, the council must give approval within 5 weeks of receiving your application unless you demand for an extension. Note the 5 weeks is usually an extreme as if it is to be approved, it will be approved in less than 5 weeks.
Note that approval for building plans or modifications typically last for three years. This means that you have within this period to commence and finish your project. If you don’t start work within this time, the council has the right to serve you a notice demanding that you submit a fresh application for the same purpose.
Understand that approval for building regulation can be rejected. There are several reasons why this can happen but the most common is that your planned modification does not meet with the technical requirements for building regulations. For example, building regulations require that the minimum head height for loft conversion should be at least 2 metres; your application could be rejected if your loft does not meet this minimum head height requirement.