Tag Archives: Roofs

Smarter Modeling & Top Link Settings

In the wake of our office presentation on Solid Element Operations, I have been getting a lot of feed back, questions, comments and suggestions on use of SEO’s and methods of modeling without them.

I want to point out three scenarios that I came across this morning. One is SEO’s done correctly, the other are wrong. These deal specifically with walls, columns and beams and their relationship to the roof elements above.

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Wall perpendicular to roof slope trimmed to roofs with upward extrusion

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Wall parallel to roof slope, extended to ridge height and trimmed with upward extrusion

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Columns extended beyond roof plane and trimmed with upward extrusion

The basic idea here is that elements are all extended beyond the roof and then cleaned up by using SEO’s. This is wrong for several reasons:

  • First, this habit will cause more unnecessary SEO’s in the project. And we have already covered why that is problematic
  • Second, these elements can interact, intersect, create voids in elements above, such as dormer walls
  • Third, these walls do not clean up correctly with their roofs in section, wall section, details
  • Fourth, it runs a risk of saving out incorrect or inaccurate IFC or SKP files

The correct method for making these walls/columns/beams flexible to design adjustments is to set them to the correct height relative to the story above. Top link the wall, even if it is grossly below the story above, as in this case where the floor to roof height is 18′ in the story settings; so the top of wall is -9′ to story above.

Screen Shot 2016-04-28 at 11.12.55 AM.png

18′ floor to floor height for floor/roof stories

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Wall Top linked to Roof and set at -9′

Gable End + Hip + Multiplane Roof

This has come up pretty frequently, in user group meetings, online forums, and here at WWA. I would try to re-explain it, but check out this link:


The graphisoft help center has done a great job of explaining a simple solution to this “complex” roof problem. One thing to note is the pitch break should be manually adjusted in the 3d window to avoid guess and check design.


If you are using Cadimage Roof Coverings in AC17 you may find it a little tough to figure out where the cover fill settings are located. Like most Cadimage tools, the Coverings tool has a lot of depth, which also means it may not be immediately obvious where the settings are. The first thing you need to do is verify the box for Use Same Pen in Plan and 3D is not checked. This is under the Display Options > 3D + Section tab.Display 3d

Next Verify that cladding is available to show on each floor option (home story, above, and below). Please note that this does not guarantee that the covering object WILL show on these stories, it just makes options for view settings available for each of the 3 view options.Display Plan View

Lastly you will need to define how the cover fill is represented on each of the three view options. In the third image you will see the options for applying fills to Plan View – Home Story, Above and Below Home Story. If the check box from the first image IS checked (Use the Same Pen…) these options will not be available.

Cladding fills

You can save the fill and pen settings set for one of the views and apply them to all three if they need to match, rather than recreating these settings for all view types.

It is also worth mentioning, for those using AC18, the fill type by story location settings are not available; or if they are I have not found where they are relocated to in the new Cadimage Coverings for 18. You can still set the cladding to show or not show in Home, Above and Below, but the fill type by location from the third image seems to be missing or relocated.


Recently a question about beam and roof matching has come up. For example, if you place a roof at a 4.75:12 slope, your beam would need to be 21.5953º (and that is missing a few digits) to get close to matching. In the beam settings this would round to 21.60º by default, since we are only able to place beams to a two digit precision.

To match a beam precisely to the roof slope you will need a working section through the roof showing the full length of the roof and beam in an orthogonal elevation view.

Screen Shot 2014-10-27 at 8.14.47 AM

Start by aligning the top node of the bottom slope end of the beam with the appropriate skin or core line of the roof (this does not need to be an end node of the roof, but does need to be snapped to the roof skin separator line). Next select the top node of the top slope end of the beam and select the “modify angle” button on the pet pallet. Last move the top node to the same line as the bottom node previously aligned. Note that you will get a checkbox or solid pencil symbol next to the cursor when you are snapped to the line.

The beam settings will still show as rounding to the nearest two decimal places, but the beam will perfectly align with the roof slope no matter how close you zoom in. From here it is a simple eye-dropper and inject command to get the other beams elevations and slopes to match.

I would also like to mention one more time, this is another reason it is critical to give similar or identical items a common element ID to differentiate them from other elements. Using the find and select tool for all beams with an ID of “Typical Rafter” and a beam width of x” will allow you to quickly isolate the beams that need to be modified to match the one that now aligns with the roof.