Understanding LOD (Level of Detail) for Design and Construction

LOD (Level of Detail) is the term used to describe how much information a drawing or model contains. Simply put, it is how you choose to show the construction details and materials of a project.


When we were designing and drawing with pen and paper only, there was never really an issue with LOD. However, now that technology allows us to model in 3D, the concept of LOD has blurred. There is a reason why Plans, Elevations and Sections are kept as simple as possible (Low-mid LOD). If we need to show a higher LOD, we create 2D construction details. This keeps the design fluid, and saves time.


However, now that we can design and draft in 3D, and a large part of what we draw is automated, why not just model everything, right? Imagine if your entire project had every material, product, connector/fastener!? Hell, it would be one giant detail. Surely, this is something that we should all be doing?


Wrong. Until our computers become way more powerful, too much detail can hurt you more than it can ever benefit you. First and foremost, it will slow down your computer to a crawl  – even for a small, custom home. But beyond the constraints of technology, it would impact your ability to quickly design and draft, and then make quick changes to your design. This would ultimately consume your time and profits.

High LOD should be saved for 2D/3D details or Actual Construction Assemblies.

But there is a balance. Obviously, if you can see (and are aware of) all of the different products and materials in your project, you can better mitigate design error and oversight. In fact, many of the available 3D BIM/CAD software only add to possible error and oversight. For example, are your walls showing structure only, or are they including surface finishes? We have seen many examples where a plan has been dimensioned from the finish surface, instead of the structure (or vice versa), without even being aware of it.


Moreover, these types of software don’t allow you to to see and manipulate the structure and materials, so that you can design and detail better.

Virtual Design and Construction software (VDC)

The good news is that there are emerging technologies that have determined the right balance of LOD. PlusSpec for SketchUp is a design and estimating BIM software that is also Virtual Design and Construction. The difference with VDC compared to BIM is that it provides a higher LOD, whilst still enabling very quick and flexible design changes.

In the above example, the circled elements in the 3D detail are elements that are simplified within PlusSpec. In a 2D/3D detail, you may show each individual brick and block. However, PlusSpec simplifies the required geometry by showing the bricks and blocks with a scaled image of the brick or block product. Why model 10,000 bricks or blocks, when you can show it with a simple surface (and still understand scale, and calculate the quantities)? In the 3D detail, the joist insulation is also shown with a thickness, and has been exactly fitted between each joist. PlusSpec simplifies this by showing the joist insulation with a surface. As the final example from this image, the 3D detail has included each masonry wall tie, and has also included the DPC. Again, PlusSpec simplifies this by showing these elements with a surface. The simplification of LOD in these examples ensures that you will be able to quickly design and make changes, while keeping your model size nice and light. Finally, it will still accurately capture the required quantities for Feasibility studies or a Quote/Estimate. As you can see though, the LOD is still quite high, which means that there is typically only minor work required for the actual 2D or 3D detail, which saves you even more time.

The problem with high LOD, is that you can get addicted to it. Before you know it, you can be yelling ‘MORE, MORE MORE!’ A good example of this is a masonry wall with stucco/render on the exterior, and plaster on the interior (or equivalent). You should not show all three layers (yet you would be surprised how often we are asked how to do this). To keep your model light and efficient, PlusSpec simplifies the wall by showing the structure thickness only. The finish material thicknesses are ignored, and they are represented with a surface material/product or colour.

The trick with LOD is that you want it to be as high as possible, without any negative ramifications (time to model, time to make changes, computer speed, etc). Simplicity is key!

If you use the correct LOD, you will be able to make design changes on the fly – and not get bogged down by unnecessary detail. However, if you use a VDC software, such as PlusSpec, you will be able to design and communicate more efficiently, and with less error. And don’t get us started on 3D details, which you will be able to take directly from your model, or model separately as a vignette. Check out our blog post on 3D details if you’d like to know more.

As always, we’d love to hear your thoughts on LOD!

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