Designing with modern methods of construction in mind

  Joe Martin
  May 23, 2023
 
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Prefabricated, Volumetric, Kit house, Pod, Modular construction are all terms associated with what is essentially offsite or factory-made construction.

Generally in the UK there is probably a stigma associated with “prefab” construction. It is often loosely connected to poorly performing post-war attempts so that it is not often considered a reliable form of construction.

However the approach offers many benefits for various projects such as housing, flats, healthcare and education. It is also a “Modern Method of Construction” (MMC) which is a construction route that may offer various advantages.

Why offsite construction?

The range of benefits to designing and building in this manner can be summarised as follows:

  • Improved quality – primarily due to a factory-controlled construction conditions,
  • Material efficiency – significant reduction in wastage,
  • Building faster and reduced labour costs – reduces onsite construction work; essentially the site construction phase is assembling a kit of modular elements, lifted into position, and finalised by a condensed number of trades,
  • Customisable – a base chassis or volume can be configured into many combinations, offering clients options and choices,
  • Steel and timber fabrication techniques are available; cross-laminated timber (CLT) construction is rapidly becoming as a favourable route.

How does an architect fit into this approach?

Commonly the architect works with the specialist design and fabrication team during the technical design stage. However, in some instances, if it is known that the scheme will be predominantly built offsite / factory-made, the architect should be working with the specialist during the initial design stages. The manufacturing techniques will influence the design and this will be conveyed in the drawings and documents prepared for Planning submission.

Collaboration and coordination

Close collaboration will ensure that the overall volumes, components and module sizes are an integral part of the developing design and not an afterthought. Coordinating such matters, prior to gaining a planning approval, should reduce the risk of having to return to the planning authority for amendments during the technical design or construction phases. Such amendments at a late stage can be costly and carry a higher risk of affecting the development programme.

A key consideration for any scheme that is to exploit this type of construction is a full understanding of how the site will be accessed, onsite storage and working space: routes for HGV delivery of large volume elements, room for setting these down, manoeuvring and crane lifting /swing requirements must be determined early on. Also, understanding the synergy of unifying the factory-prepared components and the site-constructed works; tolerances between the two must be evaluated and agreed between the various parties involved.

Cost

Although overall construction expenses may be reduced, owing to a comparatively rapid construction programme, it is worth bearing in mind that higher up-front costs are to be borne. Design team fees are ‘front-loaded’ as the scheme must be fully coordinated across all disciplines: architecture, structural & civil engineering and mechanical, electrical and plumbing engineering, at an early stage. For this reason, Building Information Modelling (BIM) is now widely adopted by the team; output from such a model is rich in information that can be utilised by the manufacturer’s designers and workshop.

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