Welcome to the secret world of permitted development. We all know that extending your home needs planning permission, right? Well, not necessarily. There are plenty of things you can do without needing planning permission (although it is often wise to obtain a Certificate of Lawfulness from your Local Planning Authority to confirm that they agree that what you want to do is permitted development – very useful when you come to sell the property). I will summarise the possibilities here, but it is best to speak to a suitably experienced Architect or Planning Consultant as the devil is often in the detail.
Up until recently, provided your house is not a listed building, in a conservation area, area of outstanding natural beauty or national park, you could build as permitted development a rear two storey extension 3m deep, a single storey rear extension 4m deep, a small front porch, a single side extension up to half the width of the original house and a loft conversion with dormer windows on the rear roof slope. You could also cover up to 50% of your garden with outbuildings that are incidental to the enjoyment of the dwelling house (i.e. not bedrooms or living accommodation).
You could also extend to the rear of the house up to 8m, but this would require an application for Prior Approval to be made to the Local Planning Authority.
In 2020, the government introduced some additional rights for houses built between 1st July 1948 and 5th March 2018 (subject to certain restrictions). The biggest of these new rights was the ability to add up to two additional storeys to a house (one storey to a bungalow) subject to certain limitations. However, an application would need to be made to the Local Planning Authority beforehand – and they can consider the impact on neighbouring properties when making a decision.
If you own commercial property, then offices can be converted to flats or houses (again subject to certain restrictions). Storage buildings can be converted to residential use, as can agricultural barns.
Perhaps you own the freehold to a purpose-built block of flats – well, now you can add up to two storeys of additional flats.
If you are looking to extend your house, but maybe it has been extended significantly before, permitted development could be a way of getting a little more floor space.
If you own an office building, but tenants are terminating their leases and working from home – maybe a change of use to residential could be a way of increasing the value.
There isn’t enough space here to detail every aspect of permitted development, particularly those relating to conversions, which could fill a book. At first glance there is much you can do under permitted development, but there are plenty of pitfalls and subtleties of wording which mean it is easy to be tripped up and fail to obtain prior approval from the Local Planning Authority, so I would recommend speaking to a suitably qualified Architect or Planning Consultant who will be able to guide you through the process.