ArchiCAD Basic Training – Module 2
2-6. Drawing a Floor Slab, Editing the Polygon Boundary

ArchiCAD Training –  (Quick Start Course – 2-6)

This 10 minute video lesson focuses on how to draw and edit a floor slab. These methods apply to all polygon elements in ArchiCAD, including slabs, roofs, meshes (used for terrain modeling), zones (used for delineating rooms or departments or usage areas) and fills (2D elements that fill an area with a hatch, poché or pattern). They also can be used in many cases to edit groups of connected elements that are selected together, such as exterior walls or lines, arcs and polylines.

We switch to the Slab tool to draw the floor, and play briefly with the various geometry options, drawing a “free-form” polygon, a rectangle, and a rotated rectangle version. Then the polygon option is chosen to carefully snap to the corners of the exterior walls and draw the slab precisely underneath the walls. Another option is shown: drawing a rectangle slab, then selecting it and editing it’s boundary using the pet palette, adding node points and repositioning them to match the wall corners. A third option is used by drawing a rectangle slab, then using the “Boolean addition” option in the pet palette to add another rectangle shape to the polygon, which very quickly makes the polygon match the walls in this case.

Additional editing options are shown using the pet palette, including offsetting edges numerically (a specific distance) or by snapping to align to another element, offsetting all polygon edges a common distance larger or smaller (especially good for footings), curving edges, and filleting corners either individually or globally for the entire polygon.

TROUBLESHOOTING NOTES: To edit any polygon (like the floor slab) you need to select it first with the arrow tool, or shift-clicking. Sometimes it’s a little tricky to select a slab when it’s “hidden” underneath the walls. You can hover over the corner or edge with the arrow tool, then you should see the pre-selection message indicating what ArchiCAD is about to select; if there is more than one element under the cursor, you’ll see a message at the bottom of the pre-selection text that mentions that there are multiple elements; you can use the Tab key one or more times on the keyboard to ask ArchiCAD to show you each of the other elements, and when you see the desired one highlighted, you can simply click to select it.

You can often simplify this process by activating the matching tool in the Toolbox – for example, highlighting the Slab tool when you want to select a Slab on the floor plan. Then, when you hold down the Shift key and hover over the edge or corner, ArchiCAD will “prefer” matching elements, and propose selecting the Slab first rather then the Wall that may also be there. Another option for quickly selecting the Slab is to switch to the Arrow tool, and make sure the QuickSelect (magnet) icon is active; then you can hover over the floor slab in the “middle” of the room or building, and ArchiCAD will see and be able to select the Slab there, perhaps without any “competition”. Note that if you have the Roofs showing, it may also then “see” and try to select a roof that covers that area; you can always use the Tab key to cycle to another element and select the Slab that way.

Final notes: sometimes the Pet Palette will not show up the way you expect, or give you all the options you are looking for. It is sensitive to whether you are pointing at an edge or a corner node, and will give you different buttons depending on which you press down on. Also, sometimes you may need to switch or activate the matching tool in the Toolbox to see all the editing options – for example, switch to the Slab tool in the Toolbox to get all the options for editing a selected Slab. And one more thing: occasionally the Pet Palette will appear to be “broken” — although the Offset Edge icon is highlighted, ArchiCAD is showing you that you’re about to drag the entire element rather than just that edge; in this case, simply click another option in the Pet Palette, then click the desired option again, and usually it will then function as expected.

Thank you for visiting the Best Practices Course website. The video lessons are available for members only. If you are an active member and would like to watch the ArchiCAD training video on this page, please login to the website. If you are not currently a member, please visit the following pages for more information and to sign up for the Best Practices Course, the QuickStart Course or for the Best Practices ArchiCAD Coaching Program. Eric Bobrow, Creator of the Best Practices Course

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ArchiCAD Training: Drawing a Floor Slab, Editing the Polygon Boundary

Let us know how you feel... (4 comments so far)

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  1. LukaszMol
    12 years ago

    I find module 2 as very useful and well prepared material. Understanding general idea of app. allows digging deeper beyond examples shown in videos without effort and frustration. As it`s quick start course some functionalities were not mentioned but I got them on my own anyway. Huge progress within last 2 days of learning Archicad. Thanks a lot.

  2. AmmarRija
    13 years ago

    Hi Eric
    I did not know the slap had these options

  3. Avatar photo
    13 years ago

    Hi Eric,

    I like the tip about using ‘add node’ to combine rectangular slabs.



  4. JacquelineCrawford
    13 years ago

    Great lessons, thanks! I’m flying through them and am looking forward to more!