Single-Storey Rear Extensions: The good news is, if you live in a terraced or semi-detached house in 2020, Local Planning Authorities have relaxed the rules and allow for extensions to go to 6 meters . If you live in a detached house, single storey rear extensions can be up to 8 meters in depth. Just be aware that if your property type is a flat, maisonette or in a conservation area, then you will need full planning permission. Side Extensions: Side extensions fall under permitted development if they do not extend more than half the width of the original house. You can extend a maximum of 3 meters as long as it is a single storey extension and does not extend pas the front elevation. Double-Storey Extension: As of October 2019, new rules are being phased in which will allow homeowners to build extensions onto detached homes without requiring planning permission, under the usual rules of permitted development. This will make adding a two-storey extension to your home no more complicated than having a loft conversion. This doesn’t mean that there is no paperwork involved in undertaking a two-storey extension, but it will make obtaining permission for the extension much simpler. Loft Extensions: Roof extensions/should be set back, as far as reasonably feasible by at least 20cm from the eaves, unless it is a hip or gable roof (measure the 20cm along the plane of the roof). The roof extension should not hang over the wall of the house. To be a Permitted Development any additional roof space created must not exceed these volume allowances: 40m3 on terraced or emi-detached houses, 50m3 on detached houses. If you believe that your property falls under permitted development, the best way to ensure a positive result is to consult the advice of an Architect to ensure that your extension follows these rules which are applicable to all extensions: Materials should match the existing house No raised platforms, balconies, or terraces Single storey extensions should not be more than 3 meters high Must not be taller than the existing building The extension should not take more than 50% of garden space