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Modern Methods of Construction

Off-site, on-track

How off-site construction can help cut time on site by 50 per cent

 Off-site construction is not a new concept. The practice of constructing homes away from the building site can be traced back as far as the Romans!  In the 1900s, we saw the development of kit homes in the US and, here in the UK, the post-war period took advantage of pre-fabrication to help address housing shortages.

Of course, construction technologies have moved on at pace since then, but there remains a degree of caution in the industry as to the benefits of off-site manufacture versus traditional methods of construction.

However, with the Government’s new 2025 industrial strategy encouraging the industry to ‘build, build, build’ and in particular the Construction Sector Deal; a £420 million commitment to build new homes, faster – off-site and pre-fabricated manufacturing techniques are gaining momentum as a means to reduce wastage, inefficiencies and delays on site.

Broadly speaking, off-site construction is one of a number of modern methods of construction (MMC), in which there is a common desire to improve predictability in the cost, time and quality of the final build. A desire to construct at speed without impacting on the finished product.

It’s not just speed of construction that is impacted positively either. Health and safety concerns are significantly reduced by constructing away from the hazards of a building site.

Indeed, the latest Health and Safety Executive’s (HSE) latest figures highlight that fatal injuries in the construction sector are four times greater than the all-industry average. While this is not as high as some sectors such as agriculture and fishing, it is still of great concern, especially as 2019/2020 saw an increase in fatal accidents to construction workers of 22 per cent above the previous low in 2018/2019.

With off-site construction therefore offering the promise of significant efficiency, safety and productivity improvements, let’s start by taking a look at some of the different methods of off-site construction.

Off-site construction methods

Today’s off-site fabrication techniques can involve anything from assembling a few component parts to an entire building structure, which is subsequently delivered to site. Key benefits include repeatability and dependability, in other words; the ability to manufacture and commission components to a defined quality standard, helping to reduce the risk of defects on-site.

They typically comprise the following areas.

First are sub-assemblies, often more complex components that require a degree of precision which is easier to guarantee off-site and which form part of a larger system, such as prefabricated doors or pre-assembled roof trusses.

Panel systems, such as floors, ceilings and walls may be constructed with the mechanical and electrical services already in place, ready for connection into the building on site and complete with high efficiency.

Volumetric, manufactured units are typically larger building components that link together to form a complete building and can be timer or steel based. Like panel systems, essential building services such as plumbing and electrics are pre-installed, sometimes even extending to internal paint finishes.

Finally, modular systems incorporate ‘pods’ that make up an entire building structure, such as a school or residential home. These are gaining in popularity, due to the ability to mass produce units at the factory for transportation to site.

Not just for housing

With this multitude of different off-site construction techniques and modern methods of construction comes a host of well-proven benefits that can help speed time on-site – and for a variety of sectors.  According to the 2019 Modular Construction: From projects to products report by McKinsey and Company (McKinsey), modular construction can speed construction by as much as 50 per cent and ‘in the right environment and trade-offs, it can cut costs by 20 per cent.’

While housing shortages, coupled with a strong labour market are likely to continue to make new housing one of the key areas of focus for off-site construction, other sectors are also predicted to benefit, delivering annual savings of up to 22 billion US dollars according to McKinsey. These include commercial properties, such as office buildings, hotels and retail stores, warehousing and public sector new builds in schools and hospitals.

The benefits of off-site construction

These methods of providing standardised components, off-site deliver a variety of benefits. A repeatable manufacturing process that delivers the same component, at the same output rate to an agreed quality standard has clear advantages in terms of predictability and efficiency. Reducing the margin for error, can all result in a faster turnaround on site, with less rework.

Speed of construction is another key area, with project start to completion times reduced significantly and the positive knock-on impact of less time required on-site.

Safety, as we have already discussed, is of prime concern to the construction industry. By removing many of the hazardous construction methods away from the busy building site to a predictable factory environment, safety concerns can be reduced.

Sustainability is another area where construction professionals are looking to make improvements. Because manufacturing in the factory can be scheduled to start as the site is being prepared, processes can run in parallel, helping to reduce waste and the movement of vehicles.  This can also create less disruption to local residents or businesses close to the construction site.

The Roofspace method

Here at Roofspace, our modern methods of construction help meet this increasing demand for improved quality and speed of delivery, from high quality roofing to whole house solutions through our i-HouseTM  and i-RoofTM products.

Our i-House OSM technology was implemented by Lovell Homes at a site in Norwich, resulting in a 35 per cent time saving compared to traditional building methods.

The i-House uses a bigger and lighter variant of the aircrete block, which are lifted by crane and assembled in a similar sequence to a timber frame build. This results in a much faster construction process than a traditional build.

Intended for domestic property construction of up to three storeys, i-House consists of inner leaves of external cavity walls, separating walls, floors, lintels, cavity closures, insulation and roof trusses, with the inclusion of soffit and fascia for the internal skin of the property.

The fact that the solution is manufactured off-site, and larger elements are constructed prior to being delivered to the site in Norwich, means less waste and dust is created for workers. This results in a safer and cleaner working environment. Furthermore, workers on site are not exposed to chemicals.

Crucially, as the homes are watertight in under a week, it has increased Lovell Homes’ construction programme, allowing internal trades to begin their work sooner than with a traditional build.

If you would like to find out more about how off-site construction solutions from Roofspace could help you cut your time on site, please in touch here.