Some of our most exciting projects in recent years have been airspace developments: that is, adding additional storeys onto an existing building.
We love them because they give us a chance to challenge ourselves. They’re usually highly constrained and require a careful design to mitigate potential impacts on overlooking and residential amenity.
The process of obtaining consent for airspace development, however, keeps changing.
In July 2020, the government introduced a raft of new permitted development (PD) rights including allowing for the erection of two additional storeys to on detached buildings that are either commercial or mixed use with flats.
Now, through Class AA, your two-storey rooftop extension could fall within the remit of PD, but only if it meets certain criteria.
Do I need to let the local planning authority know?
Yes, you do. You need to submit a prior approval application, so that the local planning authority (LPA) can assess your proposal against a few conditions such as the transport and highway impact of the proposal and design. The nature of the process means that the relevant grounds on which a decision can be made by the LPA is more limited than a full planning application, so it’s usually a smoother and quicker process.
What are the permitted development rules?
We’ve set out below the main limitations to your PD rights. For the full details, consult the regulations directly, or get in touch with us for bespoke advice to make sure you are accurately interpreting the regs.
- Additional storey(s) must be built on the main part of the building
- The extension can’t increase the total height of the extended building beyond 30m
- The floor to ceiling height of any additional storey can’t exceed 3m (or the floor to ceiling height of the existing building)
- The extended height can’t increase the height of the existing building by more than 7m
- The extension works can’t require additional supporting structures in order to make it structurally sound
- Engineering operations are limited to works to strengthen existing walls or foundations, or to install or replace services
- New access points, storage or waste facilities can’t extend beyond the curtilage of the existing building
- New storage, waste or other ancillary facilities can’t be situated forward of the principal elevation or an elevation fronting the highway
Don’t forget, this list summarises the regulations, and shouldn’t be relied upon in place of the full regulations. Get in touch with us if you need bespoke advice about how the regulations might impact on your property.
The planning strategy is key
Often, a staged approach is the best way to achieve your ultimate goals, using a combination of PD rights and planning applications.
The Stag, in Brighton is the perfect example of this.
We secured consent for Godfrey Investments in 2012 for a mixed-use new-build development. After being in use for six years, our client wanted to maximise the building’s potential. So, in 2021, we took advantage of the new PD rights to obtain prior approval for an extra storey of four apartments. Seven months later we went back to the planners with a planning application for four roof terraces, which didn’t meet the PD criteria.
By taking a staged approach we were able to establish common ground with the planners that the height of the eventual works was acceptable in principle, so narrowing down the areas for debate in the planning application. Nine weeks later, the roof terraces were approved.