Simplified design leads to more efficient construction. Design for Manufacture and Assembly, also known as DfMA, is a design process that simplifies the manufacture and assembly of various construction elements. In general, DfMA, prefabrication and modular construction are terms which are used interchangeably. Therefore, the creation of prefabricated construction BIM modelling, modular construction drawings and DfMA modelling and drawings are required for the effective implementation of DfMA. The advantages of DfMA, especially faster build times, have been especially beneficial for the healthcare sector. Build time is a significant factor in the construction of new premises or addition of new complexes or renovation of existing healthcare facilities. Just how does DfMA accomplish that?
Well, initially, it was concrete components such as columns, beams and floor plates, that were prefabricated in the construction industry. Prefabrication evolved to include more elements, such as glazed, sealed and serviced components, modularized MEP (M&E) systems, facade treatments and even entire floors that could be stacked on top of, or placed adjacent to, each other by a crane. One methodology of prefabricating components from design to construction soon became known as Design for Manufacture and Assembly, or DfMA. Products designed using DfMA are of high quality and reliability, and while using DfMA the design stage progresses to the production stage with fluidity, ease and speed. Wet and dry services can be prefabricated in the factory and connected on site, speeding up the process. In some cases, modular construction enabled the building and the site work to be completed at the same time, and depending on the materials used, modular construction has been known to reduce the overall project time by up to 50%.
Unique to DfMA is the capability to manufacture a building’s floors, walls, ceilings, rafters and roofs all at the same time. While constructing in situ, floors are placed in position, then walls are put up, and lastly, ceilings and rafters are added on top of erected walls. Using DfMA, floors, walls, ceilings and rafters can be created simultaneously and can even be assembled at a factory to be transported to the site as a module, resulting in a faster process compared to conventional construction methods.
The use of DfMA has been known to improve safety as well as speed up the construction process, especially with steel work. Connections carried out at heights can be minimized or eliminated by using prefabricated modules. In certain cases, when panels are fixed from the interior of the building, scaffoldings can be eliminated, saving the time spent erecting them and associated costs. Standard assembly practices, such as vertical assembly and the use of self-aligning parts also saves time during prefabrication in construction.
DfMA is ably assisted with the use of BIM (Building Information Modelling) technology. Embedding this technology into projects early in the design stage can minimize the time taken for the project and, as a result, the costs incurred. Hospitals, clinics and other healthcare facilities particularly benefit from DfMA, since healthcare projects typically take a long time to construct. This is due to the fact that many healthcare facilities include a variety of services that require complex data communications, clinical components and security equipment. Manufacturing individual components and assembling them into modules off site can improve the coordination of services, the quality of components and their reliability. One of the key reasons why using DfMA can save time and reduce costs is that it enables the use of fewer parts in the construction process, and the components used are not unique. Also, harsh or sudden changes in weather need not slow the process of construction, as components are fabricated in factories, safe from adverse weather effects.
Using DfMA results in certain advantages, and some of the primary objectives of using DfMA are to:
- Minimise the number of individual components
- Standardise the components used
- Avoid the use of complex components
- Employ modular subassemblies
- Use multifunctional parts
- Avoid special test equipment
- Minimise operations and processes
The introduction of BIM technology early in the design process can be vital to the efficiency of DfMA. Utilizing BIM technology in DfMA helps to realize the full potential of modularization and standardization. The BIM process enables the visualization and testing of components and modules virtually, before creating prototypes, resulting in reduced risks. Reducing risk is especially important for heavy-use areas, such as hospitals, for which construction time is crucial. Hospitals are also sensitive locations, and it is vital to limit the build time on site. Certain building types with a significant building portion that is repeated, such as hospitals, are well suited to the use of DfMA. Using BIM technology, DfMA can also cut construction time due to the fabrication off site of most of the building’s components and possibly most of the building’s floors. BIM technology also interfaces seamlessly with other technologies that drive the production of building components, an example being the ‘printing’ of concrete panels.
For hospital design, DfMA can be introduced during the bid stages of the project. The building’s structural and non-structural elements can be fabricated off site. This may include main structural external shear walls, which may be pre-installed with insulation and concrete. Facades can also be manufactured and delivered as bay-sized panels of up to 20 tons each, with windows, cladding, insulation and internal plaster boarding. After being delivered to the site, these panels can be placed in position quickly by cranes to create weather-resistant structures. Floor slabs with reinforcement do not require concrete pours on site. MEP (M&E) services can be fabricated in a factory and assembled on site, saving time.
Bathroom pods are becoming increasingly popular for prefabrication in the healthcare sector. The use of bathroom pods in construction have been known to significantly reduce the project schedule. In a project where 440 bathrooms had to be built, the use of prefabrication delivered bathroom pods 10 weeks earlier than the estimated schedule and that was before the time savings of installing pods against a more traditional route, which could add months as well as logistical challenges. Another reason why prefabricated bathroom pods work well to reduce construction time is because they present an effective solution to tight working conditions on site and poorly located connection points. The extensive coordination required early in the design process for bathroom pods can be aided to a great degree with the use of BIM technology in DfMA. BIM models help to detail the connection points and can help visualize working spaces. While designing bathroom pods, designers try to place the maximum number of connections on the edges of the module’s footprint, to minimize work above and around the pod in tight work spaces and therefore speed up the process.
In hospitals, modular buildings can be constructed as wards, theatres, diagnostic centers and support centers, such as offices. Modules can be repeated with the same design on different floors or different locations on site. These modular buildings can either be used as extensions or to construct complete hospitals. Repeated room design and standardised components created using DfMA can improve cost-efficiency, quality and minimise the risk of errors produced by changing design, all of which ultimately result in the structure being built faster.
Some of the other components for hospitals that can be prefabricated in assembly warehouses off site and then erected in situ, thus minimizing time spent locating, buying and transporting these items, are:
- Shower units
- Management offices
- Doctor and patient rooms
- Operation rooms
- Medical offices: surgical, clinical or dental
- Emergency rooms
- Exam rooms
- Diagnostic centres
- Hospital extensions
- Imaging centers
- Research suites
By investing in modular solutions, elements of hospital redevelopment can be taken off site, clearing space and opportunity for other essential tasks and enabling the continuation of high standards of patient care. In addition, when fabricated modules are of high quality the need for extra finishes are reduced, resulting in more time for other tasks. In addition to faster build times, other advantages may ensue as a consequence of using DfMA.
For example, DfMA was recently used for an American healthcare facility. Modular elements were used for patient room bathrooms and HVAC and plumbing system parts. Although reduced material waste and labor costs as well as shorter time schedules were expected results, an unexpected benefit presented itself as material cost savings, 40% to be exact. Encouraged by the savings gained using DfMA, the facility decided to opt for modular components for patient room frameworks, headwalls, rough-ins for outlets and lines. Further use of prefabricated building construction BIM work involved MEP ductwork, plumbing, fire protection and cable trays, thus expanding the scope and range of prefabricated components.
For healthcare facilities, faster construction is vital for patient care. With the use of DfMA, labor, financing and supervision costs are reduced, and almost all design and engineering disciplines can be included in the manufacturing process. In factory surroundings, weather conditions and regional climates are rendered irrelevant to work efficiency, and the risk of damaged building materials is reduced. The use of DfMA ensures that components for healthcare facilities can be designed easily, efficiently manufactured and assembled faster and at lower cost. With the early introduction of BIM technology in the design process, DfMA embodies a collaborative and integrated approach that helps the healthcare sector build faster and therefore optimize benefits.