With this advancement in Technology, this has enabled the accurate design and production of pre-fabricated materials and components of a building, including:
- Pre-cast drainage components
- Pre-cast service bridge
- Pre-cast stairs
- Pre-fabricated kitchens
- Pre-fabricated bathroom
- Pre-cast walls/external envelope (aka “flat packs)
- Modular Units (aka “pods”)
This advancement in technology has created advantages and disadvantages to having pre-fabricated building, such as:
2.1 Advantages
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Speed On-Site – Due to the main construction being in factories, in-situ assembly is rapid, saving on time and labour costs. This also reduces or even eliminate waiting times for other trades to begin their works.
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Quality – Due to the factories not being exposed to the external elements penetrating the materials and being a controlled environment, the materials strength and durability aren’t compromised. There is also the elimination of other trades coming into contact with completed works that may cause damage which can be costly.
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Less site operations – this decreases accidents and injuries that are common when working on-site. It also saves a lot of time and money.
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Welfare of staff – The welfare of staff is improved greatly due to the controlled factory environment with regards to health and safety which can be very difficult to control on-site.
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Environment – The Building Research Establishment (BRE) found that pre-fabricated homes were more energy efficient. This is due to the increased levels or insulation that are fitted in the walls and roofs whilst in the factories. Waste is an issue for sites with 25% of the UK waste coming from construction and demolition works. There is reduced by factories ordering materials to specification and the significantly less damage to materials that can be caused on-site. The reduction in transportation is significant due to factories mass ordering and producing which results in the reduction of frequent on-site deliveries. This not only cuts down on pollution but speeds up the process due to strict delivery times on-site.
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Security for workforce – the increase in permanent employment for work forces
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Single point of responsibility – from a main contractors point of view. Not having to deal with various trades and miscommunication errors.
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Accuracy – Components are built to specification so the parts can be delivered to site and slotted into place without the problems of on-site mistakes.
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Weather (inclement) – Factories do not have to worry about the external elements so there is no down time with work forces having to be “rained-off”.
2.2 Disadvantages
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Size – The size may be an issue for the requirements of tall of large buildings as a lot of factories can only accommodate a certain size. This may also cause a problem with the transportation of the components. Specialist technology for this may be required.
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Weight – The heavy weight of the components may need specialist transportation which may costly.
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Cost – Currently, the cost of flat packs/modular units are quite expensive. This reflects in the considerable reduction of time needed to construct and specialist skills required.
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Accuracy – this can also be a problem. A high degree of accuracy is required so there is no tolerance allowed for.
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Flexibility – There is extremely, if any, flexibility available. The flat packs and pods are made to client specification and once the factory begin construction, designs cannot be changed and if they are, it will be very costly.
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Labour – this can also be a disadvantage due to less labour required on-site which results in unemployment rates increasing. The need for skilled labour is required so the Government will need to play a part in achieving this.
3.0 MODERN METHODS OF CONSTRUCTION [MMC]
3.1 Flat Packs/Panels
These are more commonly used for homes. They came into production after the results of World War II due to the shortage of housing and slum clearance caused by the bombings and industrialisation. Over 1million homes were put together and were only used as a temporary measure until more homes were built but surprisingly they are still standing today.
Flat Packs are panels of ready made walls, floor and roofs mass produced in factories into sections made out or timber, concrete or steel. The panels often have wiring and plumbing inside them which saves on time and labour. They are transported and assembled in-situ with it only taking days to assemble as apposed to traditional methods that can take months or even years.
There is a lot of negativity towards flat packs due to the poor quality of previous materials and workmanship. The homes are also difficult to mortgage with lenders being apprehensive to the life expectancy of the packs.
[Picture Source: www.yorkon.com]
3.2 Pods/Modular Units
These are more commonly used for large building or mass produced buildings due to the cost and time saving features. Modular units can be pre-made rooms such as bathrooms or kitchens that are put into homes or hotels for example. Or, the units can be whole buildings such as flats or site offices.
[Picture source: www.apollo-offsite.com]
3.3 Legislation, Standards & Quality Control
The British Board of Agreement and BRE Certification are accredited systems which check the performance of housing systems. It can take over a year to gain this and cost over £100,000. If this isn’t granted, Mortgage lender and building insurers very rarely lend money or insure the property.
There are specific building regulations for the construction methods or even materials of Flat Pack and/or Modular Units. There is just the need to meet the Target Energy Performance as recently revised in Building Regulation Approved Document L – Conservation of fuel and power. This is in-line with the Standard Assessment Procedure (SAP 2005). This is in preparation for the Energy Performance Certificate that every building requires as per the Energy Performance of Building Directive (EPBD). This allows designers to have more flexibility and freedom in the design of a building whilst keeping in-line with the appropriate standards and legislation.
The British Board of Agreement also provide certification of confirmation on structural ability and durability of the manufacturers materials and components whilst ensuring they comply with Building Regulations and Standards.
Manufactures can also gain ISO 14001 for Environmental Performance. This is an internationally recognised standard for the continued reduction of impact on th environment.
4.0 EVALUATION
Currently, the demand in the UK housing sector is exceeding the supply with only 175,000 homes being built per year which is it’s lowest since 1945*. The government has estimated that there will be 3 million new households built by 2016 as per the Sustainable Communities Plan*. With the encouragement of the modern methods of construction (MMC), I believe flat packs and pods will very much be a huge part of the future in the construction of homes.
Prefabrication housing is fast whilst reducing time by 50%. This will enable the government’s estimation to be met and even succeed.
There is a lot of public apprehension and negativity towards pre-fabricated homes and buildings, this is due to the poor materials and skilled labour back when they were introduced in the 1900’s. I believe this stigma can be significantly reduced or even eliminated with the advanced technology we now have that provides flexibility in designs whilst using stronger materials that conform to building regulations as well as being more aesthetically pleasing. With the evidence from Europe that flat packs and modular pods do have high structural integrity and durability and with the increased demand in housing, commercial and public sector buildings, the many advantages listed above far outweigh the disadvantages and that of the traditional on-site methods of construction.
I believe that the demand and supply of modular pods will need to mirror each other as soon as possible, as the more demand there is, the more delays there will be with the shortage of UK based factories being able to supply.
I believe that in the future, many more UK based factories will be in production and this will provide construction companies with a ‘one-stop shop’ for their building needs especially with the ability to provide customised and authentic designs.
*Parliament Office of Science and Technology
5.0 REFERENCES
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Answers.com [2010] – Computer-Aided Design (CAD)
[on-line] Available from:
[Accessed April 2010]
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CABE [2010] – Design Process of Murray Grove, Hackney, London
[on-line] Available from:
[Accessed April 2010]
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English Partnerships [2008] - Modern Methods of Construction
[on-line] Available from:
[Accessed April 2010]
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Jablite [2010] – Your Guide to Building Regulations
[on-line] Available from:
[Accessed April 2010]
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Yorkon [2010] – Fast, Innovative and Flexible Off-Site Construction Solutions
[On-line] Available from:
[Accessed April 2010]