Can modular construction help tackle prison overcrowding?

With 87,111 people held across 126 prisons in England and Wales¹, the UK’s prison estate is already operating at around 97% of its operational capacity². And with the prison population projected to reach 100,000 by March 2030, pressure on an already overcrowded system is only set to grow³.

The government has introduced measures to ease this pressure, including changes to early release for eligible lower-risk prisoners, typically held in Category C and Category D prisons. But these measures form only part of the response. Prisons also need flexible, practical ways to increase capacity as demand changes.

Modular construction is already making a difference – such as Premier Modular’s work with the Ministry of Justice – especially across Category C and D sites. Additional accommodation and facilities can be built quickly and efficiently, helping prisons respond to immediate capacity pressures while avoiding the longer timescales associated with traditional construction.

In this guide, we look at how modular construction is helping tackle the UK’s prison capacity challenge. Keep reading or jump to a section to find out more:

• What are the benefits of modular construction for prisons?
• How is Premier Modular supporting the Ministry of Justice?
• How can modular construction assist with rehabilitation?
• Are modular prisons safe?
• Can modular prisons be both secure and sustainable?
• How can modular construction help in other areas of public infrastructure?

What are the benefits of modular construction for prisons?

Modular construction can provide flexible solutions that respond to changing needs. Key benefits include:

• Greater site security – far fewer tradespeople and contractors are required on the prison site because most construction takes place offsite. This is particularly important when working within a live prison, as limiting the number of external personnel on site helps to protect both prisoners and staff, reduce disruption and ensure the smooth running of the prison throughout the project.
• Less disruption from the weather – module production takes place inside a controlled factory environment, which can minimise the impact of adverse weather on construction timelines. This can reduce weather-related delays and overall programme times by up to 50% compared with traditional, on-site construction methods.
• Faster overall delivery – site preparations and module construction can take place simultaneously, rather than sequentially. This approach can significantly reduce the time required to get the building ready for use.
• Increased flexibility – modular buildings offer flexibility both in how they are used and how they can evolve. Modular designs can be adapted during construction and, in many cases, after completion, with additional modules added later as requirements change. This makes them well suited to the evolving needs of the prison estate, from permanent modular prison cells and rapid deployment cells (RDCs) for lower-level security prisoners to education, training, healthcare, wellbeing, workshops and purposeful activities.
• Long-term solution – modular prison buildings are designed to meet the robust security and structural requirements of a custodial environment, providing a permanent, durable solution for long-term use.

How is Premier Modular supporting the Ministry of Justice?

Premier Modular has decades of experience in supporting the Ministry of Justice and His Majesty’s Prison Service (HMPS) alongside Tier 1 contractors. We deliver NOMS-compliant facilities across the justice estate – from offices to gatehouses to holding cells, education buildings, multi-faith centres, sports halls and more.

We offer:

• Streamlined procurement – we’re accredited across several procurement frameworks, helping customers simplify procurement and reduce time and costs.
• Minimal disruption – offsite construction means fewer deliveries and less activity on a prison site, minimising operational disruption and day-to-day security concerns.
• Flexible, secure solutions – RDCs can expand capacity when needed, with options for enhanced security features including reinforced steel frames and toughened glass.
• Sustainable by design – Our modules are manufactured with zero waste to landfill and can incorporate low- and zero-carbon technologies, including solar, heat pumps, green roofs and rainwater harvesting. Designed to target BREEAM Excellent, our solutions deliver measurable savings – at HMP Full Sutton, a temporary greywater system saved over 3 million litres of potable water in two years.
• Cost-effective solutions – early engagement with our expert team helps identify the most cost-effective solution to meet your budget and requirements.
• Designed around the end user – our specialist design expertise creates bright, open-span spaces designed around the needs of occupants and staff, with flexible layouts and standard 2.7m ceiling heights.
• Dedicated aftercare – from handover to ongoing maintenance, our facilities management and maintenance teams provide tailored support across the UK, ensuring you have continued support throughout the life of your building.

Successful Ministry of Justice projects include:

Category C prison, East of England

A Category C men’s prison needed additional non-custodial facilities to support increased capacity. Premier Modular designed and installed three two-storey buildings: a 1,307m² healthcare facility with dentistry, a 1,900m² visitor and staff office building, and a 750m² commercial kitchen. Using offsite manufacturing, the project was completed in just 28 weeks. All buildings met Cat C security requirements, with secure fencing helping minimise security risks during installation.

Young Offenders Institution, South East England

Facing capacity pressures, a male Young Offenders Institution required a rapid expansion. Premier Modular, working with a key contractor partner, delivered a Cat C-certified 240-place extension comprising three cell houseblocks, alongside education, visitor, healthcare, sports changing and gatehouse facilities. The site programme took just 12 weeks. Secure fencing supported safe installation, while environmentally focused design helped the project achieve a BREEAM score of 76.23% and win a Prisons Category award.

Read more about these projects on our website.

How can modular construction assist with rehabilitation?

The condition of prison buildings can have a significant impact on prisoners’ rehabilitation. Overcrowding, ageing infrastructure, staff shortages and inadequate facilities can create environments that are not conducive to rehabilitation⁴, highlighting the importance of well-designed, fit-for-purpose prison facilities.

Modular facilities can support wellbeing and rehabilitation through:

• Spacious, open-plan interiors – creating bright, comfortable environments, especially for visitors
• Dedicated spaces for rehabilitation – providing purpose-built areas for education, training, work and other activities
• Flexible layouts – allowing spaces to be adapted as requirements change
• Comfortable, functional environments – supporting positive routines, skills development and preparation for life after release.

Are modular prisons safe?

All modular prison units are designed from the beginning around stringent prison security requirements, just as you would in a brick-and-mortar construction.

As most construction is carried out off-site at a factory, there are fewer tradespeople entering and exiting prison grounds, reducing potential security risks. Once it’s time to construct the module on-site, secure fencing is erected to segment the installation areas from the main prison.

Can modular prisons be both secure and sustainable?

Modular prison buildings can help address capacity pressures while supporting the Government’s net zero 2050 ambition. Offsite construction reduces site traffic and material waste, with our modules manufactured with zero waste to landfill. Sustainable design can be integrated without compromising the security, durability or performance required of prison facilities.

Premier Modular was appointed by Kier to deliver temporary modular buildings across four HMP sites. The project incorporated environmentally conscious features, including smart sockets designed to reduce energy waste, operational costs and carbon emissions – demonstrating how modular buildings can support both security and sustainability.

The following results demonstrate sustainability in action across the four sites:

• HMP Northumberland – 27% reduction in energy use and 24% reduction in CO₂ emissions
• HMP Channings Wood – 35% reduction in energy use and 27% reduction in CO₂ emissions
• HMP Glasgow – 38% reduction in energy use and 32% reduction in CO₂ emissions
• HMP Lancaster – 44% reduction in energy use and 36% reduction in CO₂ emissions

How can modular construction help in other areas of public infrastructure?

Modular construction can play a vital role in all public infrastructure. Beyond modular jail cells and other prison facilities, both permanent and temporary modular buildings can provide flexible, efficient solutions for a wide range of applications, including schools, hospitals and other essential public infrastructure.

Former Chancellor Rachel Reeves’ visit to Premier Modular in 2025 highlighted the value of exploring innovative approaches to all public infrastructure. We look forward to continuing that conversation as the Government considers how best to meet the changing needs of the UK’s prison and wider public sector estates.

Find out more about Premier Modular and the justice sector, or contact our team to learn more about future-proofing facilities with modular prisons.

References

1. UK Government, ‘Prisons data’ (2026): https://data.justice.gov.uk/prisons
2. BBC News, ‘About 700 prisoners to be freed on 1 October under revised early release plans’ (2026): https://www.bbc.co.uk/news/articles/cj4jnqvdny0o
3. Institute for Government: ‘How will the new prison early release scheme work?’ (2026): https://www.instituteforgovernment.org.uk/explainer/prison-early-release-scheme

4. House of Commons Justice Committee: ‘Ending the cycle of reoffending – part one: rehabilitation in prisons (2025): https://committees.parliament.uk/publications/50209/documents/271003/default/

What investment? Looks like this has been copy/pasted from somewhere else

It was paraphrased from the case study below: “As part of the Ministry of Justice’s £2.3 billion investment into new prisons, many HM Prison (HMP) sites are working on expansion projects to increase capacity. “

https://www.premiermodular.co.uk/case-study/delivering-sustainable-building-solutions-for-his-majesty-prison-service/