Constructible Models: The Crucial Level of Development for Projects


Engineers and architects value constructibility, but too often they don’t prepare their design models at a construction-ready level of development.

Find out how using a BIM application like Tekla Structures gives stakeholders the information they need early in the project lifecycle ensures successful structures.

More than ever, today’s construction projects call for constructibility. The most important consideration for any contemporary structural design is how profitably teams can install or built it in the real world.

Construction documentation is vital to ensuring a design’s constructibility. Designs based on constructible models offer far more than the opportunity to visualize the completed building more clearly.

With constructible data, designers can build stakeholder confidence in their projects by clarifying solutions to perceived uncertainties. When a building information model (BIM) includes the detailed component specifications builders need, they can plan their work more accurately and avoid confusion and delays during fabrication or onsite installation.

With all the details worked out, project teams can take on more off-site work, like prefabrication, precasting, steel framing or custom fixture manufacturing. Constructible design also helps contractors manage today’s challenging supply chains and plan for job site automation.

The conventional project management approach was to start construction before structural designs were fully developed. Onsite crews improvised how to perform many hands-on tasks, often under deadline pressures.

Today’s methods are more proactive, but design teams still don’t develop building plans in complete, functional detail. That mindset is changing because BIM technology enables all stakeholders to work from constructible models throughout the project lifecycle.

Building project stakeholders understand the potential of 3D BIM models to streamline  construction phases, including planning, fabrication, construction and operation. The question for many teams is, “How can we make this constructible design process happen?” 

Constructible design focuses on information. When teams work with comprehensive, practical data earlier in the process, they can improve project delivery.

The best way to raise BIM to the level of genuine constructibility is to apply the principles of “Level of Development” (LOD). The American Institute of Architects released LOD back in 2009, and the Associated General Contractors of America have expanded on it over the years.

When a stakeholder knows a design model’s LOD, they can assess its reliability for their needs. They understand how much thought has gone into developing a component’s geometry and detailed specifications within the model.

There are six standard levels of development.

• • • LOD 100 – Conceptual Design presents elements generically using symbols rather than geometrically. City planners and architects often work at LOD 100.

• • • LOD 200 – Design Development presents elements using generic placeholders, showing the size and shape of design elements and systems. Architects, highway designers and structural designers often work at LOD 200.

• • • LOD 300 – Documentation includes size, shape, position, orientation and quantity data for the elements. Viewers can determine measurements from the model’s geometry. Architects, engineers, quantity surveyors, cost estimators and construction managers often work at LOD 300.

• • • LOD 350 – Model coordination is the usual level of development for modeling and coordination. Models developed at this level present the parts needed for collaboration with other structural systems. These models show building system interfaces graphically, including all supports and connections. Facade estimators, structural estimators, cost accountants, quantity surveyors, building inspectors, fenestration vendors, finishing contractors and crane operators often work at LOD 350.

• • • LOD – 400 Ready for construction is a fully constructible model. Models rated at this level of development provide the data needed to fabricate all components and build the structure. These models include both graphic and non-graphic data to communicate fabrication, assembly and installation needs. Stakeholders can derive prefabrication sheets and cutting lists directly from these models and order required materials. Facade detailers, quantity surveyors, purchasing, cost accountants, project managers, crane operators, site safety officers, steel detailers, roofers, concrete contractors, glazers, electricians, plumbers, HVAC technicians, and lighting installers often work at LOD 400.

• • • LOD 500 – As-built is a field-verified model of a structure’s actual, built condition. This is the highest possible level of development, presenting a digital twin of the real-life structure at the site. Owners, facilities managers, suppliers, manufacturers, architects, plumbing and electrical designers, building inspectors, planners and highway designers often work with as-built models.

Since risk management is essential to construction project management, reducing uncertainty is vital to success. Vague, schematic models can instil fear, uncertainty and doubt in project team members.

Contractors are risk-averse and conscientious by nature, so ambiguity inevitably leads to requests for information to clarify expectations. Fielding these requests takes time, effort and resources.

The result for the project can be delays, rework, cost overruns and quality concerns. Or worse, onsite crews may make incorrect assumptions based on vague model details, causing critical errors. All these outcomes adversely affect the construction project’s profitability.

Constructible models help building project teams avoid these issues. Designing at the appropriate level of development makes your BIM dependable for all stakeholders. Modeling your design components at the optimal level of development has the following benefits:

• Engineers and detailers save time on RFIs and rework.
• Fabricators seamlessly enter data into their fabrication robots.
• Contractors install components accurately and on time.
• General contractors and project managers deliver timely, cost-effective, top-quality projects.
• Owners, the stakeholders who matter most, get to occupy and use quality structures on schedule and at a fair price.

The more information your 3D BIM includes, the more prompt, efficient, accurate and profitable your building project can become. The fundamental advantage of data-rich models is the content-enabled project workflows they enable.

The constructible design process integrates all project phases, benefiting all stakeholders and trades.  The time has come to create constructible 3D models from the beginning of the structural design process. It’s more than feasible. In today’s industry, it’s becoming crucial.

Find out more about developing constructible models using Tekla Structures by contacting BuildingPoint today.