HMP Millsike
Forterra Building Products Ltd has played a key role in delivering the UK’s first fully electric prison, HMP Millsike, through its supply of precast concrete components to Kier, the project’s main contractor. Situated on a 53-acre site near York and due to open in 2025, HMP Millsike is an excellent example of the Government Construction Playbook in action. As part of a £400 million government investment into new prison places, this facility is a flagship for the Ministry of Justice’s push towards modern and sustainable infrastructure.
The new prison will provide c.1,500 Category C resettlement places for adult male prisoners, providing a rehabilitative environment and preparing them for release. It will run solely on electricity, making it the first of its kind in the UK. Solar panels, heat pump technology and more efficient lighting systems mean it will use 68% less energy than even the most recently built prison, HMP Fosse Way.
Forterra supplied a wide range of precast concrete components, including wall panels, floor slabs, stairs and ground beams. These were manufactured offsite to tight tolerances and delivered just-in-time, in line with the project’s platform-based design and installation methodology. This standardised approach enabled rapid construction of the prison’s seven houseblocks, with over 16,500 precast elements used in total. Up to 220 tonnes of precast concrete was installed each day, illustrating the scale and efficiency of this DfMA (Design for Manufacture and Assembly)-led approach.
The project is part of the MoJ’s Net Zero by 2050 strategy and aimed to achieve lower embodied carbon and operational emissions than previous builds. Forterra’s precast concrete supported this ambition by enabling the use of efficient construction processes and reducing on-site waste. The project achieved 24% embodied carbon savings, aided by the offsite production and repeatable quality of Forterra’s precast elements.
Offsite manufacturing also brought safety benefits. Forterra’s high-quality precast components helped reduce high-risk activities on site, such as hot works and work at height, contributing to a 200,000-hour, RIDDOR-free construction record.
In addition to environmental and safety benefits, the project delivered meaningful social value. More than 765 jobs were created, along with 88 apprenticeships and training opportunities. Employment was also offered to prison leavers and individuals on temporary licence—reflecting a broader commitment to social impact across the supply chain, including from Forterra.
As the third in a series of four new prisons delivered using a standardised, MMC-first model, HMP Millsike achieved 84.2% Pre-Manufactured Value (PMV). Thanks to early and sustained collaboration with suppliers such as Forterra, the project also saw improved build efficiency and consistency compared to earlier programmes.