2.1. Quicker on site build time/shorter programmes/reduced preliminaries:
With MMC, much of the work is removed from the site and it is therefore possible to execute various activities of the project concurrently or even before the project has commenced on site. This reduces the projects construction time as the building or elements of the building can be manufactured off site while the ground and site works are taking place. MMC leads to a reduction in trades on site and a shorter construction programme which in turn leads to reduced preliminaries, overheads and a quicker return on investment for the client.
2.2. Reduced waste and better waste management:
As production is often executed in a factory controlled environment, the waste stream can be easier to manage. Exact quantities of materials can be purchased, materials can be used more efficiently and because materials are properly stored, breakages and damage are less likely to occur. Furthermore any un-used materials can be easily collected, re-used or recycled contributing to less waste. Constant monitoring also takes place within a production plant allowing new waste management strategies to be implemented without difficulty, if necessary. Waste reduction is a very significant advantage as waste from construction is one of the principle waste streams to landfills and it has been proven that a high percentage of materials delivered to site are never even used and go straight into the waste cycle.
2.3. Reduction in defects and increased quality control:
As you can imagine, a building site in Ireland, fully exposed to our rainy and windy climate is not exactly the perfect working environment for high quality workmanship.
Construction work exposed to the elements of wind and rain proves more difficult to monitor with regard to quality control. Human error is also another significant factor which deters the achievement of high quality construction as it can prove difficult to work in extreme weather conditions.
Factory based constructions forms, engage better and safer working conditions with no interference by the Irish climate and therefore a very high standard of quality control can be achieved which includes testing, trials, checks and re-checks. For more reasons than one, factory based construction provides better working conditions than a building site and in turn produces better quality too.
2.4. Increased Health & Safety:
Construction work carried out in a factory controlled environment is without doubt a safer working environment for all trades. Safety controls are implemented and monitored and safe working conditions are easier to meet and maintain. With off-site construction there is a significant reduction in the number of trades working on site and this proves more manageable from a health and safety perspective. Construction work on site can incorporate some very dangerous activities and in turn lead to a large number of causalities and/or fatal injuries. Construction is among the largest number of fatal injuries between all the main industries in Ireland. Statistics from 2002 to 2009 (as seen in Appendix A) show that the construction sector has been either the first or second largest contributor to fatal injuries in the past 8 years.
2.5. Social benefits and reduced local impacts:
MMC’s and in particular off-site construction, allow local communities to benefit from the process of manufacturing away from site. The main advantage to communities is that there is much less traffic and smaller on site work forces adding to traffic congestion in the area. Furthermore due to speedier on-site programmes, noise and pollution levels will decrease and the locality surrounding the site will be disrupted for a far shorter period of time.
Construction sites are only temporary employment locations and offer little or no amenities for the local communities whereas manufacturing facilities very often provide long term social services and economic benefits for the surrounding community. Manufacturing facilities are also more likely to invest in education and training for their workforce and develop a highly trained local workforce within their facility.
2.6. Greater efficiency in the use of resources and transport
Over the years it has been noted that the use of labour, plant and materials on building sites is extremely inefficient as is not the case with factory based activities which are kept under extreme scrutiny, monitored and controlled. Re-cycling and re-using of materials is also more difficult to enforce on a building site but is easily implemented in a factory based environment. On another note, monitoring of transport patterns and schedules can be very difficult on construction sites especially if the site is condensed and compact. With off-site MMC the number of deliveries direct to the building site is reduced and deliveries to factories can be planned and controlled so that full loads can be used and transport costs are kept to a minimum. On the other hand, transport of prefabricated or modular buildings to site must be carefully planned and heavy plant and equipment necessary for off-loading and erection requires careful site management and consideration.
DIFFERENT TYPES OF MMC
3.1. Volumetric Construction
Three dimensional units produced in a factory fully fitted out and dropped onto foundations to form a structure e.g. bathroom or kitchen PODS.
Fig 3.1 Volumetric Construction
3.2. Panelised construction
Units produced in a factory and assembled into a three-dimensional structure on site e.g. concrete wall panels, structural insulated panels (SIPS), curtain walling etc.
Fig 3.2 Panellised construction
3.3. Hybrid construction
Volumetric construction integrated with panelised construction e.g. kitchen pod as volumetric unit with the rest of the dwelling constructed using panels.
Fig 3.3 Hybrid construction