An ambitious project in Gosport demonstrates how utilising modern methods of construction is possible for all kinds of developments, as VerdeGO Living’s David Craddock explains to Roseanne Field

Portsmouth is a city known for its naval history. Since the 15th century it’s been a key hub for Navy activity, with various bases around the city’s waterfront. One such base is Priddy’s Hard, located near Gosport, overlooking the Historic Dockyard and Gunwharf Quays across the harbour. 

Priddy’s Hard was an ordnance depot, established in the mid-1700s. It was a naval fortress and produced munitions for the Navy until being decommissioned in the 1980s, at which point it was passed to Gosport Borough Council, before being passed on again to the Portsmouth Naval Base Property Trust, who also own the Portsmouth Historic Dockyard. 

The brownfield site is within a Conservation Area, and contains a number of listed buildings and structures, as well as being a listed Scheduled Ancient Monument, meaning it has been identified as a nationally important archeological site and is protected from “unauthorised change.” It also borders a Site of Specific Scientific Interest (SSSI) and a Ramsar Site – a designated wetland of international importance under Ramsar Convention. 

Despite the dilapidated state of the historically significant site and buildings – several of which were on the Buildings at Risk Register – getting to the stage of being able to make use of the site and save the decaying buildings was anything but easy, as David Craddock, founder of low energy housebuilder VerdeGO Living discovered. 

He first bought part of the site in 2016, and has since bought more of it in phases. The first phase consisted of the construction of nine modern units in collaboration with John Pardey, and received recognition from the RTPI for its architecture. 

Craddock has an extensive background in the construction of low energy buildings, having worked with closed timber panel systems for many years, as well as being a founding member of the Passivhaus Trust. “I’ve been very much involved in sustainable low energy buildings for a long time, looking at all forms of MMC and different types of renewable energy sources and ways in which we can heat and ventilate and cool our buildings,” he explains. “Not only from the end use for the customer, but how we can improve our construction processes.” 

A complex case

It was following the construction of the initial nine units that things started to get a little more complicated. The Trust had the opportunity to obtain grant funding from the Heritage Lottery Fund, and so discussions about developing sections of the site began between them and VerdeGO. In order to receive the funding, the Trust needed to match the amount, from their own funds or by raising funds by selling parts of the site. 

VerdeGO put forward a proposal to build within the confines of the site, as well as convert one of the Grade II listed buildings, and have one delisted in order to demolish it to facilitate new houses. “It was hugely complex,” says Craddock. “There was a huge amount of stakeholders, the vagaries of our planning process, and the amount of consultees we had to engage with.” 

The Environment Agency were involved due to the site’s location on the shoreline meaning there were issues with flooding and water ingress. Ecologists and Natural England were also involved as the site is home to overwintering birds, great crested newts, badgers and slow worms. There were also complications to navigate due to the SSSI and Ramsar site. 

One of the more complicated matters was the Scheduled Ancient Monument listing. “It’s probably more complex than dealing with a Grade I listed building, because it’s purely the shape of the landscape so if you even put a shovel in, it changes the shape and integrity of the monument,” Craddock explains. The site’s history meant there were Unexploded Ordnance (UXO) surveys to do, plus issues with nitrates, and the usual planning obstacles relating to architecture, style, and mass. “It was layer upon layer of challenges – everything you don’t want on a site you had on that one,” says Craddock. 

Historic England were initially concerned about the harm that would be caused to the site as a whole. “It had to be balanced with the benefit of taking a lot of buildings off the At Risk Register,” Craddock explains. “We had to take people down a journey and engage them, to demonstrate the value of what we were doing.” 

Some of the reluctance stemmed from the nature of VerdeGO’s proposal – housing, and more specifically the size, number, types and style. There was also initial apprehension from locals, although Craddock believes the understanding that the derelict, dilapidating site would be rejuvenated won people over. “To see impactful change was really good for the area,” he says. 

Despite the extensive challenges, they gained unanimous approval when the application was finally submitted, and the Trust was able to secure the funding. The application was for both VerdeGO’s housing and the Trust’s refurbishment of the listed buildings, which the funding was used for. Refurbishments included the conversion of one into a brewery and one into a pub. “The local economy has benefited from this,” Craddock explains. “We’ve also built a flood defence that protects over 200 homes from flooding, so there’s a big community benefit.”

The development

The project was split into three phases including the construction of the initial nine houses; phase two consisted of 21 houses, and the final phase of eight which is currently being finished. This includes a mixture of new builds and conversion of existing buildings: Ordnance Yard, nine contemporary homes; Moat House, a modern house linking old and new; Cook House, a terrace of four three-storey houses; Cartridge Close, a selection of three and four bedroom homes over three floors; Canary Yard, four two bedroom houses within the converted Grade II listed former Shell Painting Room; and Cordite Way, three contemporary houses within the confines of the old Rampart. 

“Everything is very different,” Craddock says. For example, within the converted homes vaulted ceilings highlight the original iron work. Others feature undercroft parking, and some having living rooms on the top floors to maximise on the views across the site and over to the Spinnaker Tower, Gunwharf Quays and Historic Dockyard. 

Landscaping was treated delicately due to the Scheduled Ancient Monument listing, with archaeologists overlooking everything.

Maximising on MMC & sustainability

All of the houses utilise modern methods of construction (MMC). “You’ve got this real juxtaposition of the very old historical setting with very modern, forward-thinking processes and systems,” Craddock says. MMC wasn’t part of VerdeGO’s plan from the outset, although it was something very much on Craddock’s radar. It came about when he realised they could utilise one of the derelict buildings on the site to set up their own timber frame manufacturing facility, that could be used not only to construct these houses but also for
future projects.

Craddock was – and still is – determined to research and develop different types of timber frame construction designs to find the most efficient system. “This was really about creating a facility which has low costs in terms of capital setup, and the machinery required, while still being scalable and allowing the building of very high quality homes in an efficient and cost effective way,” he explains. It was important to him the capital cost remained low, in order to keep the required volume moving through the factory low and therefore viable. 

David Craddock’s background in sustainable construction meant as well as his knowledge of closed panel systems, he had a lot of experience using a range of efficient and sustainable products. He wanted to bring all these elements together to create the most efficient houses possible and streamline the whole process, looking at offsite manufactured foundation systems, offsite manufactured superstructure, offsite sub-assemblies like doorsets and prefinished skirting boards, intelligent home management systems, infrared heating panels, battery storage, inverters, PV panels, and fractional hot water cylinders. “I wanted to bring all those bits in to simplify the whole thing, reduce the amount of time spent onsite, and increase the quality of the product,” he says. “You need to demonstrate it in practice so people sit up and take notice.” 

The PV panels maximise on each house generating as much energy as possible which is distributed through batteries and infrared heating panels, while the hot water is managed by fractional hot water cylinders. Figures from the completed homes show the heating accounts for only 20% of the energy consumption and the hot water 40%, and what Craddock describes as “unregulated” elements such as TVs and washing machines the remaining 40%. These statistics are another important element, Craddock says, in demonstrating the benefits of utilising these construction methods and technologies. 

Aside from sustainability, one of the other major draws for Craddock is the speed of construction. “I look at things with a fairly forensic approach, and break it down into 30 minute segments as to how quickly we can build a building,” he explains. Part of this includes looking at how soil can be repurposed as aggregate, to minimise muck away and what needs bringing in. At Priddy’s Hard, a  NUspan foundation system manufactured offsite and craned into position was used, which enabled them to do the foundations of 17 houses in two days. 

Finding the right foundation system was crucial as they had to be careful how much digging they did into the Scheduled Ancient Monument. “We tried to keep everything as it is, put piles in and build on top of those, being as least intrusive as possible,” Craddock explains. They then put the timber frame system directly on top, which required no insulation or screed, meaning the stairs could go straight in.

Having the house weathertight so quickly meant external brickwork and internal finish works were able to take place at the same time. No tiling was used, with VerdeGO opting instead for a Fibo wall panel, which Craddock says not only helped with the sustainability calculations but also negated the need for a trade, making it more efficient all round. 

The doorsets were all factory finished, arriving as a whole package including architraves, intumescent strips, and all ironmongery. “It means the quality of the first is the same as the last, you get continuity,” says Craddock. “It reduces the amount of snagging you’re likely to do.” They used a timber effect board made up of reconstituted stone and plastic, which is quick and easy to install and hardwearing for the end users. “It’s looking at the impacts your choice of material has not only for the construction process but the benefits to the end user.” 

They also make use of spray plastering, which is quicker to apply, dries faster and requires less painting over. Everything used on the project are things Craddock says developers may be using already in isolation: “The difference is we’ve combined all of them with a very efficient build system and process,” he says. The speed at which builds can happen is an element the industry needs to be prepared for, he believes, so as not to get caught out with procurement. “You need to reshape your procurement and programmes to improve the process and output and maximise on the value of MMC,” he says. 

The new owners of the homes have embraced the technology installed, which Craddock says is simple to use. “People can make it out to be complex but it’s just a change of mindset.” Not expecting too much from the buyers was part of the reason they opted not to aim for Passivhaus certification. “I didn’t want to put MVHR in because for it to be efficient, filters need to be changed; the house needs to be operated and sealed in a certain fashion. This way they don’t need to live their life in a different way,” he says. 

Recognition & awareness

As well as using it for their own developments, the factory manufactures frames for other developers, contractors and housing associations. It encompasses a showroom of sorts, as well as the manufacturing element, which showcases various products VerdeGO offer and use. “We use that as an educational facility to talk people through the whole process, all the different products that we use, and the output you get once you use them,” Craddock explains. “It’s not just about buying a frame, it’s about trying to educate people about sustainable, low energy, low carbon building.” 

Building small local factories as part of large scale developments also keeps the money within the local community – another of Craddock’s drivers. “I want to build local homes for local people using local labour,” he says. “You’re also educating and training people in new skills.” 

Craddock is passionate about the industry catching up with what he calls “building in the 21st century.” He believes the construction industry is bogged down by the way things have always been done, because of familiarity and ease, and while these methods will always have their place, MMC is the future. “We’re being so much more mindful now of our whole house carbon emissions,” he says. “By having these projects, it shows it can be and is being done, and it can be scalable.” 

He believes that MMC actually derisks the whole build process. “You still have that A to Z of construction – you start with an open field and hand over a set of keys – but it’s reshuffling it,” he says. “You concertina jobs into one, reducing the number of items and therefore the element of risk.” 

The company is currently looking at a development of 49 units near Cambridge, and are working with a housing association on supplying the superstructure for a development of
80 houses. 

To really get people to consider MMC, he believes recognition and awareness is vital. The project has won several awards, including WhatHouse? Awards 2021 Best Small Housebuilder and Best Sustainable Development, and the British Homes Awards 2021 Sustainable Development of the Year. It also helped form part of the Future Homes Standard specification. “Recognition is important,” says Craddock. “It enabled us to create a demonstrator model that others can look at and reference.” 

Further validation has come from a report by Leeds Beckett University and independent assessor Build Test Solutions, which found that VerdeGo timber frame houses performed up to 22% better on in-use energy performance versus that predicted by SAP. This is compared with “traditionally built homes” which the test found performed 59% worse than SAP predictions. In addition, energy bills on the timber frame VerdeGO houses were 50% less than a house with an air source heat hump, according to the Heat Transfer Coefficient study, which was undertaken over a three week period in winter.

The overall area has benefitted from the project with the addition of the flood defences, as well as the creation of the brewery and pub. The current residents are very happy, and with the final phase’s residents set to be the first to have walked in the area since 1750, Craddock says overall it’s a “special place. It’s such a unique spot.” 

With the project nearing its end, Craddock looks back on it fondly. “It’s been a really long journey, but one that I’m eminently proud of,” he says. “We’ve been able to demonstrate that using MMC and being aware of sustainable housebuilding systems and technologies is something we can all do. This is a standard everyone can aspire to, and everyone can benefit from.”