A CRUCIAL part of our net zero future will be creating a built environment that is more flexible and adaptable than it is currently.

If we cannot do that, then we’ll be unable to balance the increasing demand for new construction against finite resources and the essential need to reduce greenhouse gas emissions.

Without flexibility and adaptability, transitioning from a linear economy to a circular economy will be more difficult. We must work to prolong the usefulness of buildings, minimise demolition and extend the life of products and components across multiple projects.

When thinking about how to achieve that, traditional ground floor constructions represent a significant challenge.

However, specifying floor constructions that are capable of serving a range of building uses could help buildings to have a longer useful life, without having to disrupt the floor structure itself.
Why are buildings difficult to adapt?

Traditional design and construction processes mean that most buildings are essentially prototypes. Materials and installation techniques might be similar across different projects, but repetition and total consistency is virtually impossible.

As a result, even two ‘identical’ buildings will be put together in a slightly different way, and will perform differently once in use.

Buildings also tend to be designed and specified with a specific use in mind. Most of us have been in a building that is being used for something it wasn’t originally designed for. It’s usually easy to tell that a conversion has been attempted, and it often leaves you feeling uncomfortable. That can be owing to the jarring mix of design intent and current use or, more fundamentally, because unsuitable heating and ventilation is creating physical discomfort.

For a conversion or adaptation to be successful usually requires a significant investment of time and money to substantially alter the building fabric and services. That investment can end up being wasted if the building is turned back to its original use, or even adapted to yet another use, at a later time. The need to make such a large investment just goes to show how most of our existing buildings were not designed with adaptation in mind.

By contrast, extending a building is relatively simple. In that sense, buildings are adaptable if they need to be made bigger to suit growth or expansion. But what if a building ever needs to be made smaller?

A key issue with ‘familiar’ construction materials and techniques is that they can be put together on site, but taking them apart again is almost impossible – or, at least, undesirable. You could take apart a masonry wall, for example, but to reuse the materials would require knocking the mortar off every masonry unit. It is technically, but not economically, feasible.

How can we design more adaptable buildings?
Everything described above leads to the common situation of it being easier to demolish a building and start again than to try and work with the existing fabric. Such an approach, however, is not compatible with climate and biodiversity emergencies.

Existing buildings have a lot of embodied carbon tied up in them. Demolition sees the carbon already emitted effectively wasted, while more emissions are incurred through the extraction of new raw materials, manufacture of new products and undertaking of operations onsite.

Demand for new buildings also puts pressure on finite reserves of raw materials, rather than looking at how the resources we’ve already extracted can be used more efficiently.

Modern methods of construction (MMC) are often seen as the future of construction. Prefabrication and modular construction techniques can certainly use materials more efficiently, often generating more consistent quality at the same time as reducing waste. However, caution must be exercised when looking to MMC as the solution for everything.

There are different types of MMC, each with pros and cons. Some solutions described as MMC simply involve the same traditional materials and construction techniques taking place in a factory rather than onsite. There’s no guarantee the solution offered is any more capable of being adapted and reused.

Where MMC solutions offer more innovative ways of constructing buildings, there are also risks. For true adaptability to be realised, panellised or modular solutions need to be as capable of disassembly as they are of assembly. Just as knocking mortar off bricks and block is rarely done, so buildings assembled using MMC won’t be disassembled if it’s too expensive and time-consuming.

Compatibility between solutions offered by different manufacturers is also critical. If individual buildings are tied into unique systems, then the adaptability of the building and the disassembly and reuse of components is heavily tied to the popularity of any given system. Demolition remains a possibility if there’s no value in disassembling the components.

Ground floor build-ups in adaptable buildings
There are exciting developments being trialled across the construction industry that aim to overcome some of the challenges and risks described above. Design for manufacture and assembly (DfMA), and construction platforms, represent solutions that are likely to form the future of our built environment.

As part of such solutions, floors are likely to be constructed from panels or ‘cassettes’ that are compatible with, and easily fixed to, the primary structural frame. This will remove the need for wet processes onsite, like mixing and pouring concrete slabs and screeds. The amount of onsite plant and equipment will be reduced, and drying time will be virtually eliminated.

Until such time as those solutions become the norm, however, how can traditional ground floor constructions be specified with greater adaptability in mind?

One way to look at it is to consider how a ground floor could be specified to ensure that it can be used as much as possible. It could be thought of as ‘reuse’ if the occupation of the building substantially changes.

A traditional floor cannot be ‘assembled’ or ‘disassembled’ so that its area changes to match a larger or smaller building. However, it’s possible to ensure it’s capable of bearing a wider range of loads, and so be capable of serving different building uses. This can be done through the specification of the floor slab.

Floor insulation for ‘adaptable’ ground floors
It can also be through the choice of ground floor insulation. Extruded polystyrene (XPS) offers an ideal balance of thermal performance, compressive strength, robustness and moisture protection. Its loadbearing capabilities mean it’s commonly specified in residential, commercial and industrial buildings alike.

XPS requires only a minimal increase in thickness to achieve the same U-value as other lightweight foam boards, which offer slightly better thermal conductivities but less loadbearing capability – and therefore less flexibility in the types of floors they can be specified in.

Another advantage of XPS is its moisture resistance, meaning it can be installed directly on the ground with the DPM over it. The floor slab and floor finish can then be specified to suit a range of potential future uses.

Conveniently, the insulation will never need to be disturbed. It will therefore continue to deliver the intended U-value and the required loadbearing capability, protected by the floor slab and seamlessly adapting to the needs of the construction work carried out above.
www.polyfoamxps.co.uk
Rob Firman is technical and specification manager at Polyfoam