Stair Tool


The all-new Stair Tool lets you create, design and efficiently document any typical or unique Stair, at any design scale. The Stair Tool focuses on an intuitive and flexible design process, with graphical input and editing.

The Stair tool supports compliance with architectural regulations and with individual (e.g. structural or documentation) requirements. Stair structure and finish options reflect construction technology logic.

Input is available on the Floor Plan and in the 3D window, using methods similar to polyline or wall input.


Like the Curtain Wall, the Stair is a hierarchical element. The main Stair element consists of multiple sub-elements, including treads, risers and support elements, such as beams, stringers, and monolithic or cantilevered structures.

The Edit Mode, familiar from Curtain Wall, has been expanded and made available for the Stair Tool, to enable easy configuration of sub-elements.

The New Stair Tool Logic

Stair sub-elements are GDL components, allowing for versatile geometry, but controlled by a common scheme. As of ARCHICAD 21, GDL components can also include Building Materials and/or Custom profiles.

A Stair consist of Segments (polyline), with Turnings between them. A Segment can be defined as Run, as Landing, or as one of two Winder segments. Choose among Turning Types: Automatic Landing and Winder types.

Stair Input and “Solver” Technology

Stair design and construction in architecture is limited by regulations that differ by country. These rules usually control the height or length ranges of a stair steps, provide limits for the stair pitch, drive minimum widths and lengths of landings, and provide detailed construction instructions for winding stairs, for example.

To help users design stairs that meet local regulations, the ARCHICAD 21 Stair tool includes three innovative approaches:

a set of customizable construction rules

an automatic stair construction algorithm

a graphical interface with automatic solutions to resolve conflicts.


During polyline path input, instant graphical feedback shows what the resulting Stair will look like. To perfectly follow the polyline path, the algorithm automatically adjusts certain geometric values of the Stair, within the user-provided ranges in the rules.

What happens if the input path cannot produce a valid Stair that also meets the construction rules?

In this case, the ‘Solver’ appears automatically: a graphical interface showing possible variations.


The user can select any solution to see instant graphical feedback on the plan of how the modified Stair would look like in context, before choosing the best option.

Like Walls, Stairs can be linked to Stories, and so can follow changes in Story height.

If Story height changes only by a small amount, the Stairs will follow automatically (the number of risers will remain fixed, and only the height of the risers will increase – within the set Rules).

If Story heights change by a significant amount, then ARCHICAD highlights the affected Stairs in the whole project until the user changes any of the given data (e.g. number of steps or Riser heights).


Stair Tool Components

The main Stair component is its structure. Four structure types are available:

Monolithic Structure

Beam Structure

Cantilevered Structure

Stringer Structure

Each structure can then be customized: size, building material, profile, 2D appearance. Separate structures can be defined for flights and landings.


Other 3D Stair components are the Finishes: Treads and Risers. Select types from a Component list, which is not limited to pre-defined content. You can define custom components and save them using one of the predefined Stair subtypes.


As of ARCHICAD 21, GDL components can use a Custom Profile attribute (selected from the Profile Manager) and/or their own Building Material attributes.

Stairs use a symbolic 2D display only, which is completely independent from the Stair’s 3D parts. The 2D GDL sub-elements are:


Break Mark

Walking Line


Up-down Text


Stair Tool Edit Mode

Any placed Stair instance is defined by Stair Settings. However, you can use Edit mode and its dedicated sub-element specific tools to access and change the individual components of a selected Stair, or to add new custom sub-elements to it (e.g. Secondary Beam).

In Edit mode, each component (Treads, Risers and Structures) has its own Settings dialog box, enabling you to change its settings individually.

Stair Display

Model View Options affect the on-screen and output display of Stairs in 2D and 3D. They set the detail level of Stairs in Sections, Elevations and 3D views, as well as the plan-specific display (Floor Plan or Reflected Ceiling) on Floor Plan views.

Two Model View Options are available for Stair Detail Level (Full and Schematic), affecting the display and output of Stairs in Sections/Elevations, and in the 3D and 3D Document windows (including Edit mode).

In Full mode, the complete Stair appears: all 3D sub-elements can be seen in full detail.

In Schematic mode, a continuous membrane surface is used to indicate the top surface of the steps.