Long gone are the days when most buildings were constructed using simply bricks, stone, mortar and wood. Today, hundreds of materials, systems and building methods have changed the face of modern construction – seeing us build taller, faster and in more integrated ways than ever before.
As construction evolves, standards and expectations are also being raised. In this environment, with a renewed focus on regulations and more exacting building needs, prefabrication is beginning to play a far more prominent role as it offers greater control, speed and cost efficiencies at every stage of the construction process.
Offsite construction has been used since the days of the Pyramids, the Coliseum and the Crystal Palace, however modern offsite construction technology as we know it today was first introduced to the UK in 1918 in the form of steel-framed housing systems.
Today, offsite technology has taken on many different forms with systems developed to tackle a number of particular challenges. These include:
- Sustainable housing
- Achieving better environmental performance
- Buildings that are flexible enough to accommodate future changes
- Improving durability and lowering maintenance costs
- Reducing the requirement for specialist skills
- Reducing risk and increasing profitability
Sagrada Família, Barcelona
Generally speaking, many see offsite construction as the manufacturing of fully or mostly finished units that can be delivered and installed within or onto a building or structure. Used for large-scale, repetitive designs such as in hotels or residential blocks, it can be highly cost effective, faster to install and offer greater quality control but can lack variation. This is known as volumetric preassembly.
While similarly providing greater quality control and faster installation, offsite construction products focus on individual construction components and systems rather than whole sections of the structure. This gives architects and contractors on new builds or even pre-existing structures greater freedom to install complicated systems with relative ease – from structural insulated panels (SIPS), to cross-laminated timber, to heating, ventilation and air conditioning systems, to VELUX Modular Skylights.
For architects, offsite technology can present a number of opportunities and obstacles. It can be used as a tool to help construct better buildings, offering end-to-end design control, and greaterutility and visual appeal without sacrificing cost efficiency.
However, without upfront architectural involvement and proper design consideration,a project can quickly become overrun by standardised elements, bland, unsuitable design, and potential repetitive flaws.
When utilising offsite technology in a construction project, the rules are a bit different. As with cars, smartphones or even fashion, offsite manufacturing in construction needs to be built into the design process from the concept stage – taking into account every phase of the construction process, every aspect of the design, and even how materials, components and processes will be utilised.
While this is definitely challenging, it does ensure a building only needs to be designed once, rather than having to go through change after change at each stage to meet the needs of contractors, engineers, site managers and so on. But in the end, as always, the resulting building should be designed around the occupant’s needs, and the building method should be determined by their requirements.
Time is money on any project, and offsite technology can save both. It is designed to meet the needs of multiple stakeholders, providing benefits for architects, engineers, contractors, installers and project owners. It offers construction companies the ability to build huge sections of their projects or entire structures in a safe, controlled factory environment to a high standard and without the worry of planning, site or weather disruptions. It can vastly simplify construction, allowing contractors to plan more effectively, save assembly time on site and ensure a consistent quality.
Parts constructed off site can be rigorously tested before going on site, are designed for versatility and can be integrated as part of a single system from the moment they are manufactured. And as with all mass production, the greater the repetition of parts, the faster and more cost-effectively they can be produced.
3 Key Benefits of Offsite Construction
- Consistent quality through factory-controlled construction
- Reduces time, costs and disruptions on site with more reliable planning, quicker assembly and less waste
- Quicker assembly on site ensuring improved health and safety, less time working at height and less risk associated with outdoor environments
3 Key Constraints of Offsite Construction
- High initial costs
- The need to plan every stage and engage with suppliers from the concept stage
- Perceived lack of confidence in the product quality and certification
When building using offsite construction products, there can be a great deal of space and waste saved on construction sites, as well as maintenance and replacement costs over the lifetime of the building – compared to traditional building methods. However, these advantages need to be supported by proper planning to negate any issues regarding transporting huge sizes and quantities of components, navigating narrow or poor roads, ensuring quality checks and maintaining stock on site.
Once on site, many offsite systems are designed to be assembled in as little as a few minutes – with multiple ways to fit together, different configurations, easily replaceable parts and built-in rigour that very often exceeds building regulations. Designed as part of a tried and tested formula, offsite systems can take much of the guesswork out of construction on site.
Factory production ensures each part of an offsite system is individually engineered to exacting standards to ensure seamless integration with a build system, while also offering uniformity and versatility across multiple systems with identical parts, built-in redundancies and guaranteed standards.
What this means for construction on site, is that offsite systems can be installed and removed, and individual parts replaced with the minimum of effort – cutting maintenance costs, allowing for easy modification and upgrading of existing constructions and ensuring every system is greater than the sum of its parts.
Image: VELUX Modular Skylight
The pre-fabrication of flashings ensures a high-quality solution and a safe and fast installation process.
Cladding components are attached on four sides of the skylight, ensuring a water-tight connection.
Mounting Bracket and Hinge
Supplied with mounting brackets and clamps ready to be installed on any preferred sub-construction made of steel, concrete or wood finished with a steel profile at the top.
Frame and Sash
The main structural profiles consist of pultruded composite, containing approximately 80% continuous fibreglass threads and 20% two-component polyurethane resin.
Comes standard with low-energy double-glazing units.
Power Supply and Control Unit
Skylights and blind automation is powered by a ± 24 V DC power supply.
A hidden chain actuator is integrated at the bottom profile.
Integrated blinds protect against heat and glare and help to control the amount of light in the room.
Venting modular skylights and blinds controlled with the VELUX INTEGRA® system.
As one of the most iconic college structures in the United States, Sibley Hall has been a landmark of Cornell University campus since the 19th century. However, after several decades, the skylights on roof of Sibley Hall had frosted over and faded with time, the exterior steel frame of the building was in extremely poor condition and the top of the building had begun to spread apart causing exterior walls to crack.
The lead architects, Leven Betts, were challenged with modernizing the East Sibley Hall’s third floor while maintaining the integrity of the designated historic building. The renovation also needed to satisfy deferred maintenance issues, including structural repairs, window re- placements, and a new roof.
After conducting extensive research, Leven Betts chose the VELUX Modular Skylight system to replace the existing skylights. VELUX supplied a custom-designed, pre-engineered, all-in-one modular skylight system that simply clicked together, in six module sizes and configurations. Two 50-foot long skylights, each with 25 fully-automated panel modules, were installed effortlessly and at a lower cost than a traditional system.
Developed in partnership with world-renowned, London-based architectural firm, Foster + Partners, VELUX Modular Skylights are 100% prefabricated off-site, designed to meet all international standards and requirements for commercial buildings and provide an array of solutions with one modular design.
“That we could actually pop out one of the modules was really appealing to everybody. And it also made for a much easier installation” – Stella Betts, Partner at Leven Betts.
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