North Northamptonshire Council is the local planning authority. It is a unitary council, so planning, building control and the roads all sit with the same authority.
Ten conservation areas, and one on the Heritage at Risk register
Wellingborough has ten conservation areas, running from the historic town centre out to the surrounding ironstone villages. The town centre conservation area is on the Heritage at Risk register, which is worth understanding rather than glossing over. It means the character of the area is considered to be under threat, and the practical consequence is that the council is likely to look harder at applications there, not less hard. An at risk designation is not a relaxation.
In the villages the designations protect some genuinely important things. The Earls Barton conservation area exists in large part to protect the setting of the Anglo-Saxon tower at All Saints Church, which dates from around 970 and is Grade I. Setting matters as much as fabric in a case like that, so work on nearby properties can be assessed on how it affects a view rather than on its own merits alone.
Everything else
On the interwar, post-war and modern housing across the town the ordinary rules apply and a single storey rear extension often falls within permitted development. There is also the larger home extension route, allowing up to eight metres on a detached house or six on any other by prior approval, with neighbours notified and an answer in about six weeks.
Permitted development is not an exemption from Building Regulations, and a full plans application is still required. We do not make that application, but we arrange and meet the inspections that follow it and we see the work through to sign off.