Generally, converting your loft falls under Permitted Development, meaning you do not require planning permission so long as you comply with the laid down guidelines. The law specific to the enlargement of a dwelling house consisting of an addition or alteration to its roof is contained in schedule 2, part 1, class b of the town and country planning (general permitted Development) (England) order 2015 (as amended).
There are certain instances where you don’t need planning permission, and these circumstances are
When these conditions are satisfied, you have no reason to apply for permission unless your loft does not meet these conditions. In that case, you can get planning permission for your loft conversion project by applying to your local building authority, and you can also apply online.
You can either apply through the government’s planning portal online or directly with your local council. You can ask your contractor or architect to help you apply for planning permission as they are familiar with the process if you are unsure of what to do or how to go about it.
Every application cost £206, and the required documents vary from one local council to another, so you need to check which applies to you. Some local council provide application support, and for a fee, can help you with your application
Your local planning authority is mandated to decide on your application as soon as possible. Generally, it takes a maximum of 8 weeks to decide on a straightforward planning application. After the waiting period, your application can either be denied or approved. Where your application is rejected, you can make the necessary adjustments and reapply or appeal the decision.