• LinkedIn
  • Twitter
  • Youtube

The design

Living the high life – a unique design challenge


As part of WSP’s Big Housing Debate, in WSP’s report Building Our Way Out of a Crisis we were excited to explore the design challenges of improving London’s public buildings and building much needed new homes on top.

For maturing cities with burgeoning populations and diminishing space, using existing land parcels more effectively or building above existing properties to provide quality, high level homes is a natural progression.

While construction could be costly – especially in the case of building directly on top of an existing building where foundations need to be strengthened and the majority of work is done at height – this extra cost should be more than offset by eliminating the need to develop new land.

There are three options for building on an existing public facility site:

1. Build apartments on top of the existing facility in the form of an extension

2. Build an independent apartment building on top of an existing building

3. Redevelop from scratch the existing facility with the residential apartments on top

All options for this type of project will include all the normal residential development issues associated with urban development – planning policy, poor air quality, high levels of ambient noise, stretched utility capacities, climate change impacts – as well as its own unique engineering challenges. However, these are unlikely to restrict the project if addressed at the start and in our experience it is best to call on design expertise from the earliest stages to avoid prohibitive expense or delays.

Design considerations include:

  • Utility services – most urban sites have restricted utilities so it’s likely that larger overbuild schemes will require off-site reinforcement and space on site at ground level for supporting utility equipment.
  • Combined Heat and Powerplant, (CHP) and boiler flues – it’s very likely that new residential schemes will require either CHP/boilers on site or a connection into an existing heat network.
  • Foundation space – where applicable, all sites will need adequate space beyond the existing building to safely install new foundations for the overbuild facility.  
  • Over cladding – to look good, and for planning purposes, for options one and two the new development will need to appear as a whole integrated building.
  • Layout considerations – provision will need to be found for car parking, reception and alternative means of escape, bike storage, an energy centre, electrical substation, water storage and booster sets, waste handling and storage.
  • Roof space – the new roof will need to accommodate relocated roof mounted plant and equipment from the existing building.

Take a look at the housing report here and read the rest of our housing debate research using the headings below:

What Londoners think

The reality- case studies

The industry view

The research

The report

The Maths

The environment

The Politics