Two different planning routes
With an ordinary planning application, the council decides whether to grant permission for the proposal. With permitted development, the national grant is already available only for work which satisfies the relevant class, its limits and its conditions. Prior approval is one of those conditions where the legislation requires it. [3][1]
This means the council cannot simply replace the specified prior-approval tests with every matter it might consider on a full planning application. Equally, an applicant cannot use prior approval to obtain an exception to a dimensional limit or other eligibility requirement. The proposal must qualify for the right in the first place. [1]
What the council checks depends on the class
For the larger home-extension route, objections from adjoining owners or occupiers trigger consideration of the effect on the amenity of adjoining premises. The extension must also comply with the other relevant householder limitations. [4]
For adding storeys to an existing house under Part 1 Class AA, the prior-approval matters include neighbouring amenity, external appearance, air-traffic and defence impacts, and specified protected views. These are different tests from the larger rear-extension process. [5]
Do not assume that a guide headed “prior approval” describes a single procedure covering all projects. Record the full part and class, not merely the words on the application form.
Prepare the application before the work
The information required varies with the class. A larger rear-extension submission includes its description and dimensions, a plan and details of adjoining properties. The upward-extension procedure asks for scaled plans and elevations and information sufficient to assess its conditions. The relevant application fee also needs to be dealt with. [4][5]
A useful preparation sequence is to establish eligibility first, produce drawings which demonstrate it, identify the specified assessment matters, and then submit through the correct application route. Keep the submitted revision and receipt together so that the eventual decision can be matched to the actual design. [2][4]
Do not transfer a deadline from another route
The larger home-extension procedure has a 42-day period and a provision allowing development in defined circumstances where no decision is notified within that period. That is conditional on complying with the legislation; it is not a general cure for an ineligible scheme. [4]
For upward extensions, government guidance states an 8-week determination period and expressly says development cannot begin without prior approval. The missed-deadline remedy is an appeal, not permission created by silence. [1][5]
A certificate is not a replacement
A Lawful Development Certificate establishes whether described work or use is lawful. It is not an alternative means of bypassing a prior-approval condition which has not been satisfied. Where certainty is needed after a disputed procedural outcome, the legal question and supporting evidence must be identified precisely. [6][3]
Finally, prior approval is a planning matter. Building regulations and any Party Wall Act requirements remain separate parts of preparing the project for construction. [7][8]