When deciding to convert your loft into a new room, you need to check if planning permission is required. Your architect or builder should be able to assist with this, however here are some of the conditions that mean planning permission is not required
The total area of the additional space won’t exceed 40m2 for terraced houses or 50m2 for detached or semi-detached houses. If your home has already been extended, make sure you do not exceed these total as they relate to the whole house, not just the loft conversion.
The extension does not go higher than the highest part of the roof
Materials are similar in appearance to the existing house
Your house is not on designated land, namely national parks, Areas of Outstanding National Beauty, the Broads, conservation areas and World Heritage sites
If you are unsure if your loft conversion requires planning permission, it is wise to speak to your local planning authority or to your builder who will be able to advise you.