ARCHICAD 21 AECbytes Review (August 31, 2017)

In my article on GRAPHISOFT’s KCC event earlier this summer, I provided a brief overview of the new release of its flagship BIM application, ARCHICAD, which was launched at the event. This review captures ARCHICAD 21 in more detail. Those familiar with ARCHICAD know that each new release of the application revolves around a theme named after a breakthrough improvement (see my reviews of ARCHICAD 20 released last year as well as ARCHICAD 19 and ARCHICAD 18 from earlier years). The theme of the new ARCHICAD 21 is “Step Up Your BIM.” It’s a smart way of capturing both the two main highlights of this release: one, dramatically improved means of modeling staircases and their accompanying railings; and two, the advent of truly smart design tools in ARCHICAD, which significantly ramps “up” its ability as a BIM tool. Let’s explore this feature in more detail, along with the many additional improvements in interoperability, Grasshopper integration, and productivity enhancements that have been made in ARCHICAD 21.

Intelligent Stair and Railing Tools

The breakthrough feature in ARCHICAD 21 is a new Stair and accompanying Railing tool powered by a technology that GRAPHISOFT calls “predictive design.” Essentially, this technology uses the “rules” captured in popular design standards—such as those detailed in reference books like Neufert's Architects' Data or Architectural Graphics Standards, often referred to as the"architect's bible"—to create intelligent tools that can automate different aspects of design. In the case of ARCHICAD 21, this technology has been applied to the design of stairs and railings, which are governed by several standards for usability and safety such as the tread width, riser height, optimum riser-to-tread ratio, minimum width, landing placement and configuration, railing height, spacing of posts, and so on (Figure 1). Of course, in addition to general design guidelines for these elements, there could also be specific codes for different organizations, countries, building types, etc., that architects would need to comply with in the design.

Figure 1. Common standards for stair design culled from reference books such as Architectural Graphics Standards.

The new rule-based Stair tool is very comprehensive and can be used in many different ways to create staircases of different configurations, based on where they start and end, their shape, their bounding wall, and so on. The most basic example is shown in Figure 2, where a linear staircase is being created by simply selecting the start and end points, almost as if you were sketching it right on top of the model. The top image shows the tool in progress, with the starting point selected and the outline of the staircase interactively changing as you move the cursor to select the end point; the lower image shows the staircase once it is completed, with both the starting and ending points selected.

Figure 2. Creating a basic linear staircase with the new Stair tool.

The “rules” underlying the creation of this staircase can be seen and configured in the Settings dialog for the tool shown in Figure 3. Here, there are a whole slew of settings that can be fine-tuned such as the basic geometry (total height, width, riser height, landing configuration, etc.), codes and standards in the form of minimum and maximum values (pitch, total run, riser height, etc.), classification, structure (monolithic, beam, cantilevered, etc.), finish of both the treads and the risers, as well as its 2D representation in plan views. Rules that shouldn’t be applied can be turned off altogether. Different staircases with different settings can be saved as Favorites so that they can be quickly used to create different types of stairs without needing to access this Settings dialog.

Figure 3. The Settings dialog for the Stair tool, showing the large number of properties and rules that drive the creation of a staircase with the tool.

By configuring these settings, the Stair tool can be used to create a wide variety of staircases for different design situations, some of which are illustrated in Figure 4. The tool can be used in both 2D and 3D views. Once created, the stairs can be modified just as easily and intuitively as the process of creating them, with the ability to edit the boundary line as well as the base line, change the starting position and the ending position, reduce the footprint to the smallest possible area, reconfigure the landing, and so on. If for some reason the modification results in the staircase becoming invalid—that is, some of the rules are broken—a Warning dialog with this notification pops up and highlights that staircase so that its parameters can be readjusted to fix it. Another neat feature is the Stair Solver, which provides different options for the scenario in which a staircase cannot be created with the current settings and allows a user to select an alternative that would work (Figure 5).

Figure 4. Some of the different staircases in different design scenarios that can be quickly created with the Stair tool, both in 2D as well as 3D.

Figure 5. The Stair Solver popup that provides different alternate options for a staircase that cannot be created with the current settings.

In addition to the staircase as a whole, it is also possible to edit its individual components such as treads and risers, as shown in Figure 6. The example at the top shows some of the treads and risers towards the base of the staircase being extended, while the lower example shows the treads of a staircase being curved using the Morph tool to such an extent that they bear little resemblance to the original staircase. Despite the edits to the sub-components, they remain part of the Stair element, whose overall settings can still be modified.

Figure 6. Examples of editing the individual components of a staircase modeled with the Stair tool.

The new Stair tool is accompanied by a new Railing tool that lets you create railings for these staircases in a similarly intuitive way, as shown in Figure 7, simply by tracing their paths. As with stairs, railings can be fully customized with a wide variety of settings for each one of its components including toprails, handrails, posts, balusters, panels, posts, connections, and so on. The railings are linked to the stairs for which they are created, so that if the staircase is modified, the railing changes accordingly. Also, just as with stairs, the individual components of a railing can be modified while still maintaining its definition as a railing as a whole.

Figure 7. Creating railings for a stair, and the different settings for a railing that are used to configure it as required.

OPEN BIM workflow

GRAPHISOFT is already very strong on interoperability and was one of the pioneers of the IFC-based Open BIM initiative to promote open standards and workflows between AEC applications for the collaborative design, construction, and operation of buildings. ARCHICAD 21 makes additional improvements to its Open BIM workflow to bring multi-disciplinary models together for design coordination, clash detection, and data management. External IFC files, such as those created by structural or MEP engineers using their own specialized applications can now be placed as hotlinks into ARCHICAD design projects, allowing different disciplinary models to be seen in relation to the architectural model (see Figure 8). This is an improvement from earlier versions which also provided the ability to bring external IFC files into ARCHICAD but required them to be converted to ARCHICAD elements first. The new hotlinking capability avoids the need to convert the files and also makes it easier to bring updated models into ARCHICAD—you simply need to update the link in the Hotlink Manager. Of course, for the files to be correctly synchronized, they need to have a common origin as a reference, which would have to be decided on by the different disciplinary modelers in advance.

Figure 8. Visualizing an MEP model brought into ARCHICAD as a hotlink. Graphical overrides have been used to gray out the architectural model.

In addition to the visual coordination enabled by being able to inspect multi-disciplinary models together, ARCHICAD 21 also has updated its ability to run clash detection between these models with a built-in collision engine, so that you don’t have to rely on an external plug-in or tool for this functionality. Once the two groups of elements have been defined in the new Collision Detection tool for running the interference test, all the clashes that are detected can be viewed in the Mark-Up Tools palette, which opens up automatically after running the check (Figure 9). For each clash, in addition to viewing it on screen, you can also capture the graphical representation as a markup and export it as a BCF (BIM Collaboration Format) file to share with other team members and consultants. With regard to how the two groups for the collision detection are defined, there are a wide variety of options and search criteria that can help to pinpoint exactly what kind of clashes to look for.

Figure 9. Running collision detection between the structure and MEP models and viewing the clashes that are detected.

A third enhancement in ARCHICAD 21 to enhance interoperability and collaboration is a new Classification Manager that allows the different elements in the model to be properly classified. Not only does this make the model more organized and elements easier to find within ARCHICAD itself for performing required operations, it also helps to correctly identify the elements when the ARCHICAD file is exported, not just for concurrent design processes such as structural and MEP engineering but also for downstream processes such as scheduling and quantity takeoff. ARCHICAD 21 comes not only with a built-in classification system but also with the ability to import a variety of other systems such as MasterFormat, Uniformat, Omniclass, etc., which can then be used to classify elements. As shown in Figure 10, it is possible for the same element to be classified using multiple classification systems, so that when the model is exported, it can be used by many applications that may each be using a different classification system.

Figure 10. The new Classification Manager showing multiple classification systems, some built-in and some imported, and the ability to classify the same element using many of them.

Grasshopper Integration

ARCHICAD 21 continues with improvements in the bi-directional Rhino/Grasshopper integration for schematic design that had been introduced in the last release. Recall that the integration allowed native ARCHICAD/BIM elements such as walls, doors, windows, slabs, and columns to be used to create a design script in Grasshopper. The integration has now been extended to the zone element of ARCHICAD, allowing the creation of conceptual designs with zones in ARCHICAD powered by Grasshopper scripts (Figure 11). Additionally, ARCHICAD Favorites can also now be applied to the corresponding element types in Grasshopper, allowing the design elements created by the scripts to already have the desired settings and properties as captured in the Favorites.

Figure 11. The addition of Zones to the ARCHICAD elements that can be included in Grasshopper’s scripting capability and the ability to also attach settings to the script which will be applied to all the elements of that type created with it.

Productivity Enhancements

As always, the new version of ARHICAD includes several additional productivity enhancements, most of which were developed in response to customer requests. The transfer of parameters from one element to another has been made smarter with the ability to filter the parameter types that will be transferred, excluding some of them if required. A new Multiply Along Path option allows quick placement of similar elements along polygons, such as lamps alongside a road (Figure 12). There is also a Random Placement option, which allows elements such as plants and trees to be scattered within a specified area.

Figure 12. Using the new Multiply Along Path option to place multiple copies of an element along a selected path

Other productivity enhancements include improved handling of dashed polylines at corners so that they are now displayed with proper dashes, regardless of where the polyline starts or ends; new 3D Styles that allow 3D window settings to be saved and used in views, with any changes to the styles automatically applied to the views that use them (Figure 13); the ability to control Section boundaries from the Section view itself, without having to go to a Plan view to specify them; the ability to automate and customize text in labels; and the extension of the automatic dimensioning capability to the individual components of walls and slabs.

Figure 13. Saving a 3D window setting as a new 3D style which is subsequently applied to another view.


ARCHICAD 21 can be considered as a breakthrough release for GRAPHISOFT, being the first to incorporate rule-based design for BIM. The decision to start the application of this technology with stairs and railings elements is a smart one, both from a usage as well as development perspective. Stairs and railings are one of the most complex, as well as cumbersome and tedious, elements that architects have to model, and having intelligent tools that can model them quickly yet accurately is a godsend. From a development standpoint, both stairs and railings are governed by well-defined design standards (as shown in Figure 1), which makes it easier to create rule-based tools for them compared to say, the design of a window system for a room which needs to take into account a number of “soft” criteria that cannot be easily automated.

Yet, I hope that this is just the start and ARCHICAD will continue to include more rule-based tools in future releases for different design aspects that use established standards. This would help architects design more quickly and efficiently, leaving them with the time and the energy to focus more on high-level tasks. Essentially, anything in the design that can be modeled on the basis of rules should be automated. We should not have to painstakingly model every single element of our buildings—ideally, we should just be able to sketch out a schematic design and the tool should be able to create a full-fledged BIM model from it.

Of course, I don’t see this happening anytime soon, but it seems like a good goal to aspire for.

About the Author

Lachmi Khemlani is founder and editor of AECbytes. She has a Ph.D. in Architecture from UC Berkeley, specializing in intelligent building modeling, and consults and writes on AEC technology. She can be reached at

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