The Only Way is UP!

As the Secretary of State for Housing, Communities and Local Government outlined in his speech to the Conservative conference – echoing calls already made by the London Mayor – our rooftops have the potential to contribute towards combating the housing crisis. Nowhere, is this more true than in London. However, there are several challenges to overcome if both Robert Jenrick and Sadiq Khan’s ambitions to intensify existing buildings are to be realised.

Along with London Plan ambitions and the NPPF, which provides support for upward extensions, we are still awaiting a decision on permitted development rights. If this gets the green light, the challenge will be to ensure design quality, daylight and sunlight, residential amenity and townscape issues are addressed when bringing forward rooftop development. Local authorities will have a part to play in this; the production of planning guidance could assist in maintaining standards – not to mention clarity.

Of course, viability always comes into play. Building on top of existing structures can be complex, and we are increasingly seeing significantly higher build costs as a result of the structural alterations required to modify buildings. Significantly, professional fees tend to be higher as a percentage of build costs due to the onus on considering the existing structure and services for additional loading and capacity. The site protection costs can also be significant if the building remains in use during the construction period.

There is the potential for cost savings to be made over traditional construction, with the use of modular development and off-site manufacturing. Advancements in modular housing also minimise time on site, which is critical when there are other interests at play. The challenge will be in striking a balance between incentivising the affected leaseholders and ensuring that the project remains deliverable. We have seen this work successfully on projects where residents have benefitted from improved communal areas and facilities. Existing leaseholders could benefit from improved values and a reduction in service charges. However, it is not always that straightforward. Each rooftop will require its own mitigation strategy for it to be brought forward successfully.

One of the technical challenges that we have been addressing is the Existing Use Value for planning purposes, which determines planning contributions, including affordable housing. Whilst we are clear that a rooftop must have a value, the methodology behind this is not widely understood by the sector. It is important that these viability issues are ironed out – otherwise this could impact on the deliverability of our rooftops.

Central Government and local authorities both have a part to play in turning rhetoric to reality; however, we are optimistic that our rooftops can play a constructive role in contributing to London’s housing supply. We are increasingly seeing support from local authorities for the principle of roof top developments; most recently Southwark has announced plans to introduce guidance on rooftop housing.  So it’s now over to landowners and developers: are you up for it?

(October 2019)