LMJ editor Victoria Fitzgerald caught up with Steve Wightman, business development director of Caledonian Modular, at its Newark site to discuss why the firm’s offsite construction system is a sparkling example of waste elimination and value added.

Steve Wightman at a glance

  • Studied mechanical engineering at the University of Portsmouth
  • MD at Modular UK before merging with Caledonian

Caledonian Modular manufactures bespoke construction projects at its factories in, Newark Nottinghamshire and Driffield in East Yorkshire. The 50-year-old firm operates in seven factories in almost 60 acres across two sites and has been manufacturing modular units since 1997. The company began by providing prison cells for the Ministry of Justice but now manufactures projects ranging from single story structures to high rise buildings.

Steve Wightman is the business development director at the organisation and he is passionate about the lean nature of Caledonian Modular’s business processes: “Caledonian Modular provides design, manufacture and installation service for offsite construction projects.

“Our process contains several stages including planning, design, manufacture of modules offsite, transportation and building onsite.

“At the planning and design stage we break the building down into a series of transportable elements, parts that we can manufacture in the factory, put on a truck and transport to the site. We can then manufacture the sections on site and reassemble the building out of a series of units.

“Like a Lego block that’s roughly 40 ft long and 50ft tall and about 12/15 ft wide. We have two quite differential things to consider: to find a way of manufacturing in a factory environment an element that has been designed to be constructed onsite, for most constructions the starting point is – I have an area and a plan, I’m going to put a load of components in a field and build my building. So building components are designed to be transported to the site in small bits for the building to be assembled.

“The allegory we use is this: how would you feel if you ordered a new car and they delivered all the components to your front garden to build there?

“Instead of doing this we assess the needs and analyse the building. We examine the drawings and look at the balance between transport requirements, the rooms required, the services and information needed. Then we break the building into sections to deliver the best combination of factory content, robustness, deliverable portions, transportation, cost etc.”

Mr Wightman assured LMJ that the process has to be lean to be successful.

“We take the process from the construction site and move it to the factory. Part of the procedure is asking how are we going to do this in the most cost effect way possible? The idea is, if we are building a ten story building in our factory and every part is built here on the ground, it’s much easier to access, it’s much safer, it’s much easier to deliver the materials, it’s much easier to control the quality. It’s much easier to control the efficiency of the whole process.

“We have a series of slices that make up the building. We make a steel box, which is the structure of the building, we then put the components in that we need to fit – doors, windows, walls, insulation and electric, to name a few. We put cladding on the outside and a roof on the top.”

Mr Wightman revealed a drawing of the overall building and the sections that were being created: “These pictures are all designed so we can finish the rooms in the factory.”

“When trying to be as cost effective as possible we look at it like this: if we design and manufacture it here in the factory it costs us £1, if we reengineer it on the shop floor it costs us £10, if we have to reengineer it on site it will cost us £100.

“The firm is always aiming to do it at the design stage. What we have here is not a production line, it’s a process driven system, so every box has roughly 30 processes, and they will take about 20-25 days to occur.”

“The first process is to make the box, the structure itself, the wall the electrics, the lining, add the fixtures, paint it and test it, all before it goes to site. The box stays where it is because it’s big and we bring the materials to the units. It’s a slightly back to front manufacturing process in many people’s books, but it is a very precise process and the process is controlled.

“There is a set of documentation that accompanies each unit. It tells us who is doing what, all the checks that have been carried out, who signed it off, a regulated quality control system that you don’t get on a construction site.

“Everything is logged against the individual that carried out the work, the materials used and what batch they are a part of. Every unit is uniquely identified, what it is and where it’s going to go in the finished building, the sequence the box comes off the shopfloor so we can build them into the site in the right sequence. The paper audit trail stays with the box throughout its lifecycle, which means anyone can see where the module is in its lifecycle.

“It is a lot faster to complete the work this way, nothing impacts the building process, if it’s raining, work can still continue, you don’t build on a building site when it’s throwing it down with rain. We are carrying out work in parallel so we don’t have the regular linear process of a construction site.

“One of our buildings would take approximately half the time that a traditional building would take. If you are in the business of generating revenue from your building, like a hotel, you can open earlier with this process. You can’t sell today tomorrow, so the revenue benefit is significant.

“This process is also safer because we have very little working at height, everything that we are doing here is at ground floor level. Engineers have a flat floor to work on, so towers and scaffolding can be properly controlled.”

Steve told LMJ about how the process allows the firm to control, reduce and recycle waste:

“Caledonian Modular reduces waste as part of the design process and tries to recycling up to 97.5% of waste from the factories. Modular building projects also involve fewer traffic movements. In one project, a 2,000 bed development provided a 1,290 tonne reduction in CO2 – that’s the equivalent of planting 5,000 trees.

“We are buying in materials with minimum packaging, we control the recycling of this packaging materials, we generate probably a quarter of the waste that is generated on a normal construction site. Web buy in a lot of materials cut to size, so when we design the building we design all the sheeting and we’ll order all of those cut to size in the correct pack sizes, so we’re not cutting waste off, there’s no redundant operations, it’s all about making that process as lean as possible.”

“We save time with this process. With project start to completion times cut by up to 50%, disruption to clients and the local community is minimised, a particular benefit in the case of a school or hospital, for example. Work in the factory can be scheduled to start at the same time as preparing the site, so the two processes can take place in parallel, resulting in an accelerated build programme.

“And because a high proportion of the build and fit-out is completed in the factory, from internal and external walls and staircases to fully fitted en-suites, on-site time required for final finishing is reduced.

“The process is predictable, it doesn’t matter if it rains, if there’s an underground sewer, we can carrying on doing what we need to do in the factory. Work is not stopped by external factors or processes, more predictability in costs, delays and times.

“We also segregate waste here. We have bailing systems in the factory, separating plastic, cardboard, timber, plaster, mastic tubes, sheeting, and different bins around the factory. Waste is put into the units by the guys, and because any waste that we do generate, is produced in a controlled factory environment, it’s easy for us to control waste, clean the floor, separate the waste, we have deals set up with various providers, that manage and control our waste.

So what’s next for Caledonian Modular? Steve told LMJ the firm is setting their sights on the mass production of houses, as well as, continuing to remain lean and sustainable.