Sustainable housing provision: A case for the vertical extension of existing buildings

Charles Gillott


Charles is a Civil Engineering graduate who completed his master’s with the department of Civil and Structural Engineering in 2019. As part of this, his final year research project began to explore the potential of sustainable housing provision through the vertical extension of existing buildings; a theme which continues throughout his PhD.

Charles’ wider research interests are centered on the circularity of material flows within the built environment and ensuring sustainable development through whole-building adaptation and re-use.


Rising house prices mean that, in September 2019, the average cost of a ‘first-time’ home in the UK reached almost £200,000 (ONS, 2019). This is the result of a historic under-supply of affordable residential accommodation, something which has also contributed to the near-record levels of homelessness currently observed in the UK.

An ever-growing demand and amassed deficit of over 4.8-million homes now means that, in order to meet the 15-year target set by the current government, a total of 380,000 new homes must be built each year (Wilcox et al., 2018). Considering that just over half of this number were completed in the year proceeding June 2019 (Ministry of Housing, Communities and Local Government, 2019), this represents a formidable task for the UK construction industry. 

As well as practical issues surrounding the construction of such large quantities of residential accommodation, additional challenges arise from the UK’s commitment to the Paris accord and the resulting legal requirement for the construction industry to reach net zero emissions by 2050. This pertains both operational and embodied carbon, dictating that potential solutions to the housing crisis must provide sustainable, energy efficient and cost effective residential accommodation through the use of reduced and/or low-carbon materials.

The Role of Vertical Extension

One way in which this may be achieved is through the adaptation of existing infrastructure. This serves to curtail the ongoing cycle of demolition and reconstruction through the re-use of whole buildings; improving energy and material efficiency via a significantly less energy-intensive construction process.

Of the suite of potential adaptive strategies which may be employed, the vertical extension of existing structures has notable additional benefits. These typically result from the fact that it serves to yield new usable floor space rather than simply renovating and/or repurposing existing space; something which is of particular importance when considering its use in the provision of large quantities of residential accommodation

Research Methodology

Due to the fact vertical extension remains within its infancy, the primary factors inhibiting its widespread adoption relate to uncertainty surrounding its safety and viability, as well as the amount of residential accommodation it is able to yield. This work therefore aims to increase understanding of the potential of vertical extension as a means of future sustainable development. 

Initially this will focus upon structural considerations; with the UK building stock being analysed to identify typologies with particular suitability for future vertical extension. A simplified framework of assessment for the rapid identification of reserve structural capacity within such structures will then be developed, and its validity ensured through a suite of case-study structural analyses.

The scope of Charles’ work also extends to consider stakeholder perceptions of vertical extension as a viable construction method; uncovering potential enablers of, and challenges to, the widespread adoption of this approach. The most pertinent technical, cultural, and regulatory considerations identified as part of this research will also be used to inform subsequent work. This will be in the form of a multi-scale assessment, whereby the number of residential units which may be obtained through vertical extension will be determined at the single-building, city and regional scale.


Charles has been working with Grantham Scholar Will Mihkelson and other University of Sheffield experts to develop a tool that encourages those involved in the design and construction of buildings to engage with the circular economy and build more sustainably. Find out more about Regenerate.


Sheffield newspaper The Star featured a story on the Regenerate tool. Read: Sheffield university academics argue more buildings should be renovated to aid post Covid-19 recovery.

Social media and further information

You can find out more about Charles’ research from his Research Profile




Dr Danielle Densley Tingley

Senior Lecturer in Architectural Engineering


Prof. Buick Davison

Deputy Head of Department Professor of Structural Engineering