6 MMC (Off Site Production) REVISION 6 MMC (Off Site Production) 1

Past Exam Papers Dec 2011

Aug 2012 Dec 2012

Aug 2013

Aug 2014 Dec 2014 UK

Dec 2014 KL

6- Modern Methods of construction 1. Off-site manufactured – Volumetric 2. Off-site manufactured – Panellised 3. Off-site manufactured – Hybrid 4. Off-site manufactured – Sub-assemblies and components 5. Non off-site manufactured modern methods of construction

Modern Methods of Construction 1. Volumetric construction systems construction Shortage in housing su 1. Three-dimensional units produced in a factory. 2. Fully fitted out before being transported to site and stacked onto prepared foundations to form the dwellings. 3. Volumetric construction is also referred to as modular construction. 4. These units can be made from most materials including light gauge steel frame, timber frame, concrete and composites. 5. The units are sometimes used alongside panels (ready made walls, floors and roofs) in hybrid construction.

Modern Methods of construction 2. Panellised construction systems Flat panel units built in a factory and transported to site for assembly into a three-dimensional structure or to fit within an existing structure. Systems can include wall, floor and roof panels to create the complete structural shell. Factory-made structural floor and roof panels are known as ‘cassettes’.

Types of panellised Construction:

Open Panels

Unitised curtain walling 2. Panellised construction systems (Considerations) Unitised curtain walling

Modern Methods of construction Hybrid construction Volumetric units integrated with panellised systems. Hybrid construction is also referred to as semi-volumetric construction. Highly serviced areas such as kitchens or bathrooms can be constructed as volumetric units, with the rest of the dwelling.  constructed with panels.

What are the general issues associated with the use of offsite production? Offsite production has its complexities as the unit produced off-site has to be well-integrated within the building. Details of interface with mains supply for electricity, water, sewage are crucial. Attention to detail is key here! Otherwise the project may be prone to problems and delays. Effective communication will be essential between the offsite manufacturing team and the construction team! Interface management and the additional on site works required in relation to any design alterations thus becomes important. The method involved include: manufacturing, delivery to site, final positioning, Installation, protection and installation Offsite production has its complexities as the unit produced off-site has to be well-integrated within the building. Details of interface with mains supply for electricity, water, sewage are crucial. Attention to detail is key here! Otherwise the project may be prone to problems and delays. Effective communication will be essential between the offsite manufacturing team and the construction team! Interface management and the additional on site works required in relation to any design alterations thus becomes important. The method involved include: manufacturing, delivery to site, final positioning, Installation, protection and installation

Labour and training 1. Do we have enough labour? 2. Are they are appropriately skilled and qualified? Positioning and installation of pods, tiling to floors, mechanical and electrical work. Cleaning of pods due to tiling, repair works and unauthorized usage. There is a need for an in-depth understanding of the skills requirements to support the wider uptake of offsite production. Positioning and installation of pods, tiling to floors, mechanical and electrical work. Cleaning of pods due to tiling, repair works and unauthorized usage. There is a need for an in-depth understanding of the skills requirements to support the wider uptake of offsite production.

Transport Specially designed trucks are used to transport cell to reduce the total height of the laden trucks. Out-to-out dimension of the cell modules is critical since wider load requires escort and may limit transportation time to daytime only. Total load height also limits transportation route because low pedestrian bridges, flyovers and tunnels are to be avoided when transporting high modules. Issues: Police called away from escorted loads, can lead to stranded loads, delays, increased crane hire costs. Road closures and out-of-hours delivery ‘windows’ create restrictions, and can lead to large delays if missed. Solutions: Better reconnaissance and planning, use of specialist handling contractors, better liaison with the Police (Police escorts are no longer mandatory), avoidance of road closures, good organisation and selection of lifting equipment. Specially designed trucks are used to transport cell modules as shown in Figure 12 to reduce the total height of the laden trucks. Out-to-out dimension of the cell modules is critical since wider load requires escort and may limit transportation time to daytime only. Total load height also limits transportation route because low pedestrian bridges, flyovers and tunnels are to be avoided when transporting high modules. Issues: Police called away from escorted loads, can lead to stranded loads, delays, increased crane hire costs. Road closures and out-of-hours delivery ‘windows’ create restrictions, and can lead to large delays if missed. Solutions: Better reconnaissance and planning, use of specialist handling contractors, better liaison with the Police (Police escorts are no longer mandatory), avoidance of road closures, good organisation and selection of lifting equipment.

Cranes Remember there are cranes installed on-site and mobile cranes! Horizontal jib crane is widely used in the construction industry. It requires assistance in erection and this is usually provided by a suitable sized mobile crane, erection times vary but on average a time of two to three days can be expected for a crane of thirty metres square. Erection of this type of crane is normally carried out by a crew and an engineer, trained in the specific erection procedures required. At the conclusion of the erection the crane will be subjected to a thorough examination and an application of a 25% overload followed by the setting of the safety devices. Jibs of 50m and longer are available for applications where greater area coverage is required, and tower heights of up to 180m can be readily found for the project that needs this sort of lift height. A range of hoist and trolley winches are offered by the crane manufacturers, providing the crane user with a wide choice of hook speeds and pull combinations. Rail-mounted bases are often available for this type of crane. Remember there are cranes installed on-site and mobile cranes!

Lifting Jib crane tends to be used where special circumstances exist that would restrict the use of a horizontal jib tower crane. The main advantage of a luffing jib is that both jib and suspended load can be kept from over areas where there intrusion is not wanted. As far as its erection is concerned it follows the same lines as the assisted erect horizontal jib tower crane discussed previously, each erection being followed by a thorough examination and test.

Site layout and access String diagram Site organisation

The string diagram is an effective way of visualising the transport and distribution on-sites. An observer count the movements of the worker, machine, materials, etc. Or even all the movements on site depending on the scope of the study. It is often the case that the positioning of materials and the layout of temporary roads, scaffolds, access points, etc often develops haphazardly as work proceeds. As a result, this leads to delays, wastage and inconvenience and could impinge on productivity levels.