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  • User AvatarEric Bobrow { Rob - One more general, I would recommend the Best Practice of defining the dimensions of the actual element precisely; for example, drawing the... } – Mar 08, 10:42 PM
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ArchiCAD Basic Training – Module 4
4-1. Intro to Roof Construction for ArchiCAD 10 through 14

ArchiCAD Training –  (Quick Start Course – 4-1)

This 42 minute lesson teaches the methods used for constructing roofs in ArchiCAD 10 through 14. If you are working with ArchiCAD 15, it is still a good idea to watch this video since there are many similarities, and I share some valuable tips in the video as well as on this page that will be helpful to you.

A box of 4 walls is created off to the side of the ground floor (20’x30′ or 7 m x 10 m), then the walls are selected and multiplied 6 times using the Multiply command (right-click, select Move > Multiply). The Multiply dialog box is briefly examined, and the Drag / Increment option is chosen. These groups are spaced 30′ or 10 m apart; each will be used to demonstrate a different method for drawing roofs.

1. Shed Roof: the roof tool is activated, and the Rectangle geometry method is selected. The first two clicks are placed at the outside edge of the left hand wall, and define the “pivot line” for the roof, a virtual line in space where the roof is horizontal  at the height set in the roof dialog box or Info box. The third click with the “eyeball” cursor is made within the building outline, and indicates the upward slope direction. Then (in the case of the Rectangle creation mode) two clicks place the opposing corners of the shed roof.

A marquee is placed with a heavy border (to be able to see all stories within that area) and then these walls and roof are viewed using the right-click > Show Selection/Marquee in 3D (or keyboard shortcut F4 on Mac, F5 on PC) command. The roof is selected and its slope is adjusted in the Info box.

The four walls are selected using the Select All shortcut (TIP: activate the Wall tool in the Toolbox, then use the Edit menu > Select All Walls command or Command-A or CTRL-A), then their height is increased in the Info box. With the walls still selected, the Trim to Roof command is chosen from the Design menu. (Note: in AC15 the corresponding command is called Crop to Single-plane Roof). The walls are now trimmed to match the current slope of the roof.

The roof slope is adjusted downwards, but the walls stick up above it; they are then trimmed again with the same command. The roof is tilted higher, but the trim to roof command doesn’t make the walls grow, so in the wall settings dialog the Undo Roof Trim (in AC15 — Undo All Crops) button is used to restore the walls to full height so they can be trimmed properly.

After undoing the last trim, a superior method of cutting the walls under the roof is demonstrated using the Design menu > Solid Element Operations (SEO) command. (Note: in ArchiCAD 15, the SEO command is now located in the Design menu > Connect submenu; however the preferred command for this process is the one called Trim to Roof/Shell, also in the Connect submenu.) The walls are chosen as Targets, the roof is the Operator, and the operation is Subtraction with Upwards Extrusion. This method keeps an ongoing connection between the elements, so if the roof slope is adjusted the walls continue to be trimmed underneath them.

Finally, the roof overhang is created by selecting the roof on the floor plan and using the pet palette option to Offset all edges. (TIP: this option is available when any polygon element is selected and you press down on a corner node point; it’s located in the upper right of the pet palette). A gesture confirms the direction (to expand or contract the polygon) and the tracker is used to set an offset of 1′-0″ or 300 mm for the roof eaves.

2. In the second set of walls, a rectangle roof is created that extends exactly half-way across (the position is determined using the special snap “half” option). A second roof is drawn from the other direction. After drawing a new marquee, the walls and these two roofs are viewed in 3D; the roofs create a gable end, but the end wall needs to be extended and trimmed. The wall is selected, then its height is changed to rise above these gable roofs, then it is trimmed using the SEO method.

Eave overhangs are created by selecting each roof and using the Offset Edge option in the pet palette. (TIP: this option is available when a polygon element is selected and you press down on an edge rather than a corner; it is found in the upper row in the middle of the pet palette.) This needs to be done for each roof separately and one edge at a time.

3. Next, a rectangle roof is created only part way across, and another one is drawn from the other side only part way. In 3D, the first roof is selected and a keyboard shortcut is used to extend the opposing edge to meet this roof plane. To use this technique, select one roof as the controlling roof, then hold down the Command or CTRL key and position the mouse cursor over the edge of the other roof (NOT the corner) and click (make sure you are still holding down the Command or CTRL key).

To complete joining the roofs, the first roof is deselected (click in “empty space” or hit the Escape key), then the second roof is selected to control the action. Command or CTRL-click the edge of the first roof to adjust it to meet the second. The roofs have met at the mid-point of the wall to create a gable, as they did before.

These two adjustments are removed by using the Undo command twice, in order to demonstrate how this works when the roof slopes are not the same. One roof slope is changed to a smaller value in the Info box, then the other roof edge is Command or CTRL-clicked. It adusts to a different position. When the process is completed and viewed in 3D, it is clear that the connection is good, and that the ridge line is in the proper position given their differing slopes.

4. Two rectangle roofs meeting at the half-way point are quickly created to start out this example, in which a third roof will be added to create a hip roof configuration in place of the gable. The bottom gable corner of each of the two roofs is adjusted using the pet palette option to move just one node at a time. (TIP: These nodes or corners are repositioned along the ridge line back a bit further than the expected position of the hip – this makes it a bit easier for the next steps since they won’t overlap the newly added roof.)

A third roof is added that has a pivot line along the wall edge that goes horizontally across the “bottom” of the four walls. This roof is drawn using the polygon option rather than the rectangle one, to allow for it to be a simple triangle shape. After it is drawn, it is selected, then the Command / CTRL-click method is used to reposition each of the hip edges of the other two roofs. The result is viewed in 3D, where the final work is done: each of the other roofs is selected in turn, and the corresponding hip edge of the triangle roof is Command / CTRL-clicked to position it to meet the controlling roof.

The other end may be changed to a hip if desired, using the same approach; this is not demonstrated onscreen.

5. The polyroof construction method is used to create four roofs quickly that have the same slope. This time, it is done by clicking on all four corner points; in step 6, the magic wand is used. After the polygon outline is completed, a dialog box comes up that asks for confirmation of the pivot line height and slope and offers other options including number of levels, roof thickness, overhang distance, and eave angle (perpendicular, vertical or horizontal). After these settings are reviewed and the OK button is clicked, the roofs appear instantly; they are viewed in 3D and appear as expected.

6. The polyroof method is used again, but this time the magic wand is used to automatically trace the outline of the walls instead of clicking each point. (NOTE: you can bring up the magic wand by holding down the Space bar on the keyboard, or choosing the Design menu > Outline Polygon with Magic Wand command. To work, a suitable drawing tool should be active, and no elements may be selected.) After clicking the corner of the walls with the magic wand, the same dialog box comes up for height and slope, etc.; the roofs appear when that dialog is closed.

When the roof configuration needs to be adjusted after the automatic hip generation, this may be done easily by editing the roof polygons. In this case, one of the end hips is selected and deleted, and the two adjoining roofs are adjusted to create a gable end in its place.

7. The wall outlines are adjusted to create an “L” shape. The bottom wall is extended to 28′-0″ or 9 m using the stretch option of the pet palette. The eye-dropper is used to pick up the setting of the wall tool, and a new wall is created to go up from that corner 12′-0″ or 4 m, then one more wall returns to close the addition. The extra piece of the original right-hand wall is trimmed away using the Command or CTRL-click method. (TIP: To do this successfully, make sure nothing is selected, and that your cursor is over the edge of the wall rather than a corner point; hold down Command or CTRL and click with the scissors, which should have turned black to show you that you were over an edge that it could trim.)

The roof tool is again selected, and the polyroof geometry method chosen. The magic wand is used to create a series of roofs easily around the entire group of walls. The result is viewed in 3D.

TROUBLESHOOTING NOTES: Sometimes is may be difficult to select an element that is located in a position shared with other elements (for example, a wall may be right on top of a slab edge, and when you click, ArchiCAD selects the slab rather than the wall). However, there are a few ways to control this precisely.

If you are using the Arrow tool to select (or are holding down the Shift key to get the Arrow tool temporarily), and you pause over an element, you will see the “pre-selection highlight” telling you what ArchiCAD sees there and what it will select if you click at that moment. If this edge or corner is shared by more than one element, you will see an indication at the bottom of the highlight tag text, with the words “Multiple Elements (TAB)”. Hit the Tab key on the keyboard one or more times to cycle through each of the elements selectable under the mouse cursor position; when you see the right one highlight, click and ArchiCAD will select that one instead of the others.

An alternative method is to switch the current drawing tool in the Toolbox to match the element you want to select. For example, instead of having the Arrow tool active, you may activate the Wall tool; then when you press down Shift to get the Arrow cursor, ArchiCAD will “prefer” selecting Walls rather than other elements. If you switch to the Slab tool, it will pick out Slabs first, etc.

It may be easier sometimes to simply move your mouse to a place that is unambiguous, where the element you want to select is not overlapping another element. For example, instead of trying to select the wall by its outer edge that is shared with the floor slab, you may select the wall by its inside edge instead. If the Quick Select (“magnet”) option is turned on for the Arrow tool in the Info box, then you may select an element anywhere within it, rather than having to be on an edge or corner. Experiment with turning this on and off to understand how this can help you control your selection.

Finally, be aware that if you are over a node or corner point (a “checkmark” rather than a “mercedes” cursor), ArchiCAD will prefer selecting an element with a node at that location, and will ignore other elements that simply have an edge that passes through that point.

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: Intro to Roof Construction for ArchiCAD 10 through 14

Let us know how you feel... (14 comments so far)

The comments are closed.

  1. MattJoyner
    4 years ago

    Thanks Eric, when I came in the next day I noticed the faint start arrow overlay on the course and am watching them online now, matt

  2. MattJoyner
    4 years ago

    Can’t view it on my iPad either but I get the audio. My laptop is windows based…..what gives

    • Eric Bobrow
      4 years ago

      Hi Matt –

      I just checked your account, and can see that you recently purchased the Roof Modeling Course. This gives you access to lessons in Week 16 (Roof Modeling and Documentation) of the Best Practices Course. This page (here) is part of the QuickStart Course section of the website, where you do not have access.

      The actual videos on roof construction from QuickStart (this one plus the following two in this Module) are also posted in Week 16 Part 1:
      which you do have access to. Go to that page, and you will be able to watch all of these roof basics lessons, then continue on with the other ones in the Roof Course.

      Please use the website navigation menu Special Courses > Roof Modeling and Documentation to see the lessons that are included in the Roof Course.


  3. MattJoyner
    4 years ago

    Well I updated windows media player and STILL only get the audio but no video………..

    • Eric Bobrow
      4 years ago

      Matt –
      Please see my reply to your other comment (above).

  4. DouglasTeiger
    4 years ago

    Hi Eric,

    I got a couple of questions for you:
    1. When i draw a polyroof, i do not get the “polyroof settings” dialogue box. The roof just appears. How do i get to this dialogue box?
    2. I see that when you click on your polyroof, each roof face is a separate item. When i draw my polyroof, all faces are one unit or one element…but not a “group”.
    I’m on Archicad 15, is that why i’m having these issues?

    • Eric Bobrow
      4 years ago

      Hi Douglas –

      In ArchiCAD 15, the process is different. When you do a multi-plane roof, you may choose a rectangle hip, rectangle gable, or polygon outline option for the basic geometry. Then, when you draw the outline (any of these options) ArchiCAD will complete the roof based on the Roof Settings – there is no dialog box.

      The multi-plane roof system you have just created is a single entity in ArchiCAD 15 and later; you can adjust individual planes (changing the slant or making an end into a gable), but they are all part of one element.

      Please refer to the next lesson, which explains the methods applicable to ArchiCAD 15 and later.


      • DouglasTeiger
        4 years ago

        Thank you!

  5. AmmarRija
    5 years ago

    hi Eric
    When I want to connect tow roofs the White scissors appear to me instead the Mercedes sign, but I get the same action?

    • Eric Bobrow
      5 years ago

      Ammar –

      The appearance of the cursor will vary depending on a lot of factors. The scissors generally indicates that you are about to trim something; you’ll get this when you have nothing selected and you hold down the Command or CTRL key. A white scissors means you are hovering over empty space or something that cannot be trimmed; the scissors will turn black when you are on top of something ArchiCAD is ready to trim.

      You need to select one of the roofs in order to connect it to the edge of another roof. Frankly, I don’t recall what the cursor looks like, and it may vary depending on a variety of factors. In any event, you should select one roof, then hold down the Command or CTRL key and hover over the specific edge of another roof that it can connect with (this generally will create a ridge, hip or valley between the two roofs), and click. The roof that is clicked will reposition that edge to where it meets the roof that is currently selected.


      • AmmarRija
        5 years ago


  6. MariyaLilith
    6 years ago

    Thanks for explaining an easier way to make the surfaces of a hip roof meet!


  7. HagithPopper
    6 years ago

    Hi Eric,
    It is a real pleasure , learning from you. Just what I need. It is unbelievable how much knowledge and useful information you deliver in your course. I stop struggling with the program now that I begin to have an understanding of the logic and structure of ArchiCad, thanks to these excellent courses.

    • Eric
      6 years ago

      Thank you Hagith. I really appreciate that you take the time to add a comment and share your feelings about the lesson and the course.