The Importance of LOD400 modelling for Mass Timber Structures

Dayne Davis

Associate - Timber
BG&E
The construction industry has always been at the forefront of adapting to new technological advances, ensuring that the infrastructure we live in is as sustainable, efficient, and advanced as possible.

One such innovation that has taken the construction sector by storm is Building Information Modelling (BIM) and, more specifically, the LOD400 level of development. When considering mass timber buildings, understanding, and leveraging the benefits of LOD400 modelling becomes even more crucial.

What is LOD400 Modelling?

LOD, or Level of Design, is a benchmark that denotes the level of detail and accuracy within a BIM model. The scale generally runs from LOD100 (conceptual) to LOD500 (as-built), with each increase in number indicating a higher degree of detail and precision. LOD400 modelling, specifically, provides intricate details, including precise geometry and other specificities that are essential for fabrication of the timber products from anywhere in the world geographically as well as the coordination and planning of construction and construction sequencing on site.

Advantages of LOD400 Modelling for Mass Timber Buildings

Precision and accuracy play a significant role when detailing a timber structure to LOD400 level.  As timber is a natural material, meaning it can have inherent variability, LOD400 modelling, with its detailed geometric representation, ensures that each timber component fits perfectly with its counterparts, reducing wastage and ensuring structural integrity.  It is important, and often mandatory, to build in construction tolerance when completing the modelling, especially when different structural materials are interfacing such as concrete to timber or steel to timber connections.

These models aren’t just theoretical; they are designed to be directly constructible, leading to more efficient building processes by containing all the necessary data for fabrication and construction, thereby creating predictable plans and streamlining efficiencies both in the field and factory.  As the timber elements are manufactured and sent to site in a specific order, as per the model numbering, this allows the builder the ability to fully plan their delivery sequences and allows the carpenter on site to plan the installation and erection sequence on a daily basis.  Essentially it is comparable to assembling a large-scale Ikea set of components.

Engaging a manufacturer too early in the design process might lead to a design heavily influenced by the manufacturer’s preferences or constraints. By developing an LOD400 model independent of the manufacturer, numerous advantages can be realised:

  1. Unbiased Design: An independent model ensures that the design remains true to the architect’s vision and the client’s needs, rather than being influenced by a manufacturer’s capabilities or limitations.  This will allow the team to explore different procurement options in the market and allow the building team to consider both local and international supply options based on the project’s costs, local procurement, and constructability requirements.  We also must consider that by undertaking an independent design process we are not limited to only working with specific products like CLT and GLT, but we can also explore other timber products on the market which could provide alternative advantages and disadvantages. 
  2. Open Procurement Process: By not being tied to a specific manufacturer from the onset, there’s an opportunity for a more competitive bidding process. Different manufacturers can assess the independently developed model and offer their services, leading to potentially better pricing and quality.
  3. Flexibility in Choice: An independent model allows for flexibility. If during the construction phase, a certain manufacturer is unable to deliver, having a manufacturer-independent model ensures that switching suppliers won’t derail the entire project.
  4. Ensures Quality: By not being immediately committed to a manufacturer, there’s an inherent quality check. Manufacturers are aware that their work will be compared against others, driving them to offer the best possible materials and services.

In conclusion, LOD400 modelling, with its intricate detailing, offers a robust foundation for mass timber building projects. By ensuring that this modelling is conducted independently of manufacturers, architects and builders can ensure that the design remains true to its original vision, and the procurement process remains competitive and unbiased. As the construction industry moves forward, leveraging these advanced techniques will ensure that our buildings are not only structurally sound but also efficient, sustainable, and true to the designer’s vision.

Related Resources:

Balancing Concrete, Steel and Timber: The Future of Architecture and Structural Design

Mass Timber: revolutionising the construction industry

Cost Considerations for a Mass Timber Office Building

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