By Kim Hyde
The use of prefabrication for the Construction Industry is by no means a new idea, but the rapid changes in both legislative constraints and ecology awareness has had a massive impact on construction methods. The use of Structural Insulated Panels (SIPs) offers many advantages; strength, energy efficiency, less noise penetration, reduced CO2 footprint, speed of construction … the list goes on!
Accuracy is the key with any prefabrication. With the ever-increasing pressure on timescales, prefabricated building components arriving on-site require a perfect fit, any errors can be costly in materials, labour and possible contractual penalties.
Accuracy in design is passed directly to those responsible for the manufacture of the prefabricated components, but downstream legislative requirements for BIM also have an impact on the initial design methods employed so that metadata captured with the 3D design is available and complies with BS-1192 and ISO-19650 standards.
When considering CAD design tools, Autodesk’s unsurpassed portfolio of products has continued to lead the market in providing solutions from concept to reality. In this article I will provide an example workflow for SIP-based construction to demonstrate how some functions in CAD design (both old and new), starting from simple 2D PDF data, through to adaptive 3D design and beyond.
Step-1 - 2D PDF to 2D AutoCAD Underlay
When I surveyed several design offices, it soon became evident that when receiving data from the architect, 2D PDF was the common format. This first video demonstrates the capture using AutoCAD of the PDF to a fully vectored 2D drawing, then using this as an underlay for the 3D design using Inventor.
Step-2 – 3D Skeletal Model
The next step is to create a 3D skeletal model using the underlay captured in AutoCAD. An outline of the ground floor-plan is used to create the basic building shape in 3D, elevation information is also used for the height and roof pitch details. The material is set to glass to provide transparency and the skeletal part (including the underlay) is placed into an assembly ready for the creation of each fabricated wall.
Step-3 – 3D Wall Frame Creation
The prefabricated design for each wall begins with a 2D sketch in Inventor, this includes the extreme wall edges and extra lines to represent the timber frame locations. Inventor’s Frame Generator is used to create the timber frame using a custom timber library, then joints are added to finalise the frame.
Step-4 – Adding the SIPs Panels
In this step predefined Inventor iCopy assemblies are used which are adaptive to the size required; the user simply picks 3 corner points to define both size and placement and the SIP will adapt to the selected size. Any specific SIP type can be authored as an iCopy template, the one in the next video uses OSB clad foam insulation.
2D Drawing, Annotation and BOM
The final step is to simply create Inventor 2D drawings complete with BOM associated parts lists configured to include size and quantities of materials.
Revit, PDM, PLM and more …
So what’s next? … well don’t forget Inventor’s BIM output for Revit that can include RFA data for single SIP panels, or prefabricated wall sections … and don’t forget about managing and sharing the data by using Autodesk’s Vault with collaboration to BIM 360 and Fusion Lifecycle.