Offsite Construction - Frequently Asked Questions

What is Offsite Construction (OSC)?


Offsite Construction includes a multitude of subsets each of which has in common a degree of manufacture and assembly of building components, elements and/or modules in a factory setting for transportation to the construction site. The complete process can include planning, design, manufacturing, prefabrication, transportation, and assembly. By integrating the offsite process in the planning and design stages, the supply chain can be optimised for significantly increased efficencies, and through the effects of quality control procedures in factory settings, a higher standard of finished building is achieved. Terms used to describe the factory processes involved include Offsite Manufacturing, Offsite Production and Offsite Fabrication.




What is Offsite Construction otherwise known as? Are there other terms used to describe it?


Terminology varies. Other terms used to descibe Offsite Construction include:

  • Offsite Manufacturing (OSM)
  • Precision Engineered Building Systems (PEBS)
  • Modern Methods of Construction (MMC)
  • Rapid Build
  • Prefabrication
All derive from the same principle - buildings which include a proportion of factory manufactured elements for asembly on site.




Are there different categories of Offsite Construction?


Offsite Construction types can most easily be categorised as either 2-Dimensional (2D) Panellised Systems or 3-Dimensional (3D) Modular Systems. These systems are sometimes combined when a hybrid approach to building design and construction is used. Elements of buildings such as staircases and window and door systems can also be considered as Offsite Construction components. PANELISED SYSTEMS (“2 DIMENSIONAL”) These systems are generally further classified as ‘open’ or ‘closed’ systems. Open panel systems are normally not insulated, and would include systems such as the more traditional timber frame systems used in Ireland. Closed panels systems generally have the insulation installed in the factory setting, and these systems can be further developed in the factory by including doors and windows, services, and finishes such as internal linings and/or external cladding. MODULAR OR VOLUMETRIC SYSTEM (“3 DIMENSIONAL”) These systems usually comprise factory-completed units which are typically fully finished internally. By employing this offsite manufacturing system, the offsite construction process can deliver kitchen, bathroom, bedroom and living room pods which can be positioned on site to provide complete turn-key units. The final structure can then be easily provided with an appropriate cladding system to complete the building structure.




What type of buildings can it be used for?


All types of buildings. For example, Evolusion have been involved to varying degrees in the following types of buildings: - low-rise housing developments; - high-rise apartment developments; - multiple use buildings; - hotels; - health-care buildings; - educational buildings, and more. There are no limiting factors when it comes to the uses of Offsite Construction.




I’ve heard that OSC is as good as, if not better than, traditional building methods. Is that true?


Yes, OSC delivers in terms of better performance, quality, compliance with regulations, efficiency and durability.




Is there a range of Offsite Construction building systems available to contractors?


The range of high quality Offsite system types is already extensive, and is growing quickly as new, progressively more innovative sytems are becoming available, and these system types vary in terms of base materials used (e.g. light gauge steel, timber, precast concrete, insulants etc.) and in the degree of offsite input. 2-DIMENSIONAL PANELLISED SYSTEMS Light Gauge Steel (open and closed panels) Image below courtesy of Vision Built Timber Frame (open) Timber Frame (closed) Image below courtesy of Cygnum SIPS (closed) Image below courtesy of Kingspan Precast concrete Insulating concrete formwork Image below courtesy of Integraspec 3-DIMENSIONAL MODULAR SYSTEMS Image below courtesy of Vision Modular Prefabricated Prefinished Volumetric Construction (PPVC)




What are the advantages of Offsite Construction?


1. SPEED OF CONSTRUCTION Offsite Construction provides significant reductions in construction time due to a combination of factors, including reduced levels of activities on site, the fact that it enables scheduling of certain activities to occur concurrently rather than sequentially, and the use of lean processes such as "just-in-time" manufacturing, whereby components/elements/modules etc. are fabricated and delivered to site exactly when needed in the construction sequence. 2. BETTER PERFORMANCE Offsite Construction delivers much enhanced overall building performance, particularly in the areas of elemental thermal performance, thermal bridging performance, and airtightness levels. 3. HIGH QUALITY Factory Production Control (FPC) processes are generally employed throughout the Offsite manufacturing industry. These control plans drive repetitive, simplified procedures to ensure more predictable product delivery, and result in consistently high quality output. 4. COMPLIANCE WITH BUILDING REGULATIONS Tightening of regulations, particularly in the areas of thermal performance and airtightness, has led to much greater difficulty in complying with requirements when employing traditional building methods. The scope and precision afforded by Offsite Construction methods enables full compliance with the most onerous regulations effectively and efficiently. 5. VALUE FOR MONEY Both due to the significant time saved on site, and the efficiencies in material usage through offsite design and manufacturing processes, costs can be significantly lower than traditional building methods. Indeed a study by KPMG in 2016 found that Offsite Construction delivered 7% net financial project savings. 6. CUSTOMER SATISFACTION Customers from developers to end-users will be satisfied with the value for money experienced, and the quality of the final delivered product, with minimal defects and a consequent major reduction in snagging. 7. WASTE LIMITATION Whereas waste is a major aggravating factor on traditional building sites, the factory environment in which Offsite Construction components are manufactured is controlled and waste is minimised. Material usage is optimised through the design and subsequent fabrication processes, resulting in lower material input and reduced waste, which can correspond to a 20% - 40% overall reduction in waste.




Could it be said that there are misconceptions about Offsite Construction?


Yes. There appears to be a number of misconceptions currently circulating about Offsite Construction. Some believe that it only delivers short-term or temporary buildings, harking back to earlier decades when "prefabs" were used to provide temporay accommodation. Nothing could be further from the truth. Modern Offsite Construction methods deliver buildings which are typically of higher quality than those built using traditional methods of construction. Greater levels of performance can be attained, particularly in the areas relating to thermal performance, buildings are more durable, and compliance with all current building regulations can be more easily achieved.





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