Unlike in the world of human interactions, popularity is equated with quality in the world of technology. The AEC industry is firmly supported by the technological advances of our age, and prefabricated housing is becoming increasingly popular. The emergence of prefabricated or modular construction in the housing industry is an affordable and reliable solution to the challenge of quality housing worldwide. Prefabricated housing, sometimes known as prefab homes, prefabs or modular homes, are manufactured off site in sections, from just bathrooms to entire floors, that can be transported, placed or assembled to form housing units. Prefabricated housing can be independent dwelling units for individual families (houses) or single units which have been stacked on top of each other to form multi-storey housing or apartment blocks. How useful prefabrication is in the housing sector, why it is so and who can deliver services key to accurate prefabrication design are some of the things we will explore.
So, what are prefabricated buildings?
Prefab buildings can be built from components (such as panels), modules (in the case of entire modular homes, houses on wheels) or sections (parts of manufactured homes) constructed off site and transferred to the site when they are ready to be installed. A team of technical experts attach the different services to the building layout. These can include double-storey homes and customised homes. Modular or prefabricated homes can be created in sections and then transported on site to be put together as part of the construction process or installed. Whole rooms, such as bathroom pods or kitchens, can be created in a factory setting as prefabricated units. Steel frames can be erected on site to ‘slot’ in the prefabricated units or entire concrete foundations can be laid into the ground in readiness for the new home to arrive. Financing, construction and appraisals of these homes are carried out in the same way as for regular homes. Prefabricated houses can also be assembled on production assembly lines, which are transferred in complete sections or floors to the site, where these complete home units are connected floor by floor and then also connected to the location’s main water supply, sewage system and electrical lines.
How are they constructed?
They are usually constructed in factories that are some distance away from the actual housing site, indeed they could be in a different country. These purpose-designed factories effectively consist of assembly line environments, where different elements and trades come together at different stages of the assembly line to add the various components to the building. Starting with floors, walls and ceilings, the structure moves along for internal fixtures and MEP elements such as piping, plumbing, boilers, bathrooms and entire kitchen fittings, before being moved across to finishing areas such as glazing, doors, electrical fittings and even bathroom tiling. Once the house is assembled, it passes through final QA checks before being handed over to logistics teams for transport to its permanent site.
Plumbing and electrical lines are connected to the city’s water and electrical connections and the prefabricated sections are sealed. Prefabricated homes can have a number of rooms and be of different designs. These homes can be set on a permanent foundation, blending in seamlessly with other regularly constructed homes. Repairs on the homes are conducted by the real estate company involved in its sale.
During the settling-in time period, a prefabricated home ‘settles’ in to the location, after which some cracking of the drywall could occur. Appliances that were incorrectly installed can be repaired by changing the wiring or plumbing, and the ventilation, heating, cooling, plumbing and electrical systems can be properly installed by a set-up crew.
One of the driving forces behind a successfully assembled and reliably functioning prefabricated home is the effectiveness of its design. Increasingly, architects, engineers, contractors and trade contractors use BIM (Building Information Modelling) construction drawings at some point as part of DfMA (Design for Manufacture and Assembly). DfMA is a design process that groups the design for manufacture, or the ease with which parts will be made for a product, with the design for assembly, which refers to the ease with which parts will be assembled. DfMA helps the design team reduce manufacturing and assembly costs by identifying, analysing and removing waste and inefficiency from a product’s design. DfMA modelling and drawing is fast becoming synonymous with design for prefabrication.
Construction drawings, or shop drawings, graphically illustrate the details, data and specifications of a prefabricated design, contain information about the MEP (M&E) systems and include the details of prefabricated components. BIM technology is part of the larger virtual design and construction (VDC) process that helps find solutions to challenges faced by subcontractors and designers before building prefabricated components in the factory.
Advances in technology have made it possible and indeed preferable to outsource the delivery of BIM services such as modelling and drafting. Outsourced firms specialise in delivering drawings and models quickly, using the latest software, such as Autodesk 3ds Max, Autodesk Revit, Autodesk Navisworks and others, and by employing well-qualified experts. Modular construction drawings provided by these CAD drafting firms are typically accurate and error-free.
Prefabricated construction has reportedly been used in the world’s tallest building, the Burj Khalifa, in Dubai and in the construction of the prestigious Sydney Opera House.
Advantages of Prefabrication
- Faster completion of projects, therefore reducing costs
- Diverse uses – can be used to create high-rises, single-storey construction, villas, townships, as well as to create ceiling slabs, terrace blocks, wall panels, columns, staircases, bathrooms, light fixtures, etc.
- Customisation – unique property specifications can be accommodated easily, resulting in reduced expenses
- Durability – prefabrication in the structural aspect of construction bolsters structural strength, sometimes helping to withstand earthquakes and other natural disasters. Concrete panels are created with elements of high quality in a controlled factory environment and therefore last longer.
- Well suited for certain sectors that have repetitive design elements, such as student housing, educational institutions, healthcare facilities, prisons, police stations and senior housing.
- Increased and more efficient quality control in factory settings
- Safer and less stressful working environment for labourers in a factory than on site, especially in crowded areas, as on-site dangers are eliminated for workers
- Less on-site space is required to assembly components which have already been assembled off site
- Less waste is generated during construction, since prefabricated component waste is disposed of at the factory and not transported to the site
- Competitive edge – allows flexibility in design decisions till the nth moment
- Saves space – housing can be built in cramped spaces in tight schedules and take up less space
Modular construction in the housing industry has expanded its scope for buyers and builders. Buyers have more options to choose from and builders have more build options for construction, changing the overall construction landscape. Projects see MEP contractors use an increasing number of modular construction plans during collaboration. Prefabricated construction is more affordable and more green, since such buildings are better sealed against drafts and there is improved quality control systems in factories, thus leading to improved insulation and better energy efficiency. This will ultimately benefit neighbourhoods and residential and commercial projects.
The various advantages of using prefabricated housing can only be enjoyed when the DfMA modelling and drawings are flawless. Since this demands considerable time and resources, an increasing number of Western firms are looking overseas for their prefabrication design services.
Benefits of Outsourcing Prefab Design Services
- Cost reduction, since skilled labour and expenditure on resources overseas is significantly less expensive
- Use of advanced tools and technologies, such as AutoCAD and Revit, by experienced and well-qualified human resources
- Standardisation of drawings across projects, so that MEP installations and other services are made easier
- 3D axonometric drawings of the entire construction project are generated, showing methods and means by which individual subcontractor components or systems can be placed in the project
- Skilled draftsmen and other technical professionals work faster, maintain accuracy, provide complete audit trails with drawing references, approval records
- Faster turnaround time, since overseas firms employ ready and dedicated teams of trained personnel capable of working to constantly changing specifications, helping to complete projects on schedule
- Increased flexibility, as outsourcing allows Western firms to pick and choose services according to need. The flexibility thus generated helps expand the business.
Outsourcing prefabrication design services is thus an increasingly popular option, and this approach will save time, increase productivity, ensure higher safety levels and increase profits. Using Revit, AutoCAD and other software to create modular construction drawings and models helps provide high-quality prefabricated design support for Western firms in the industry.