Message: A polyline (perhaps a roof plane, countertop or slab) is supposed to be closed

Reference Number: KB-00847
Last Modified: July 23, 2021

The information in this article applies to:

Chief Architect Premier or Chief Architect InteriorsHome Designer Professional or Home Designer Architectural or Home Designer Suite


I keep seeing the following error message in one of my plans. What does it mean?

"A polyline (perhaps a roof plane, countertop or slab) is supposed to be closed but has a gap between two of its lines. A line or arc has been moved to close the gap."


This error message displays when a CAD based object, such as a roof plane, has been edited or altered in such a way that its perimeter has been broken. The program responds by closing the gap in the perimeter so that it can be generated in 3D.


In many instances, it is not strictly necessary to correct this problem as the program has already taken care of it for you.  It is recommended, however, that you take the time to locate the problem and make sure that the program's solution meets your design needs.

In some cases, the program will help you identify the object by displaying a circle at its location in floor plan view immediately after the error message displays.  If you encounter the error message when generating a 3D view, however, you will have to locate it yourself.

Objects affected by this error message

Typically, the problem object is either a roof plane or a custom countertop; so you can focus your search on these object types.

Occasionally, other CAD-based objects are affected by this problem, including:

  • Roofs

  • Skylights

  • Custom Countertops

  • Slabs

  • Terrain Features and Modifiers

    Please note that not all products have the tools for creating some of these object types.

Rarely, this error message can occur when a small gap between walls defining a room is detected. This gap may be caused by a slight misalignment between two wall segments.

There are several ways to find the affected object in your plan. Before doing anything, it is a good idea to make a copy of the plan file with a distinct name and save it on your Desktop.

To find the problem object

  1. Open the plan in which the error is occurring and select File> Save As  from the menu.  In the Save As dialog:

    • Click the Save in drop-down arrow at the top of the dialog and select Desktop as the location of the new copy.

    • In the File name field at the bottom of the dialog, erase the old name and name this copy "Trash".

    • Click the Save button to close the dialog and create a copy of the plan.

  2. Look at the program window and confirm that the plan file that is now active is called Trash

    • If you do not see this name, do not proceed to the following steps. Instead, repeat this sequence beginning with Step 1.

  3. To find the problem object, begin deleting sections of the plan until the error message stops appearing.

    • Use the Delete Objects dialog to delete objects by category.  Select Edit> Delete Objects  from the menu to access this dialog.

    • Delete portions of the plan in a logical progression, such as floor by floor, from left to right or top to bottom.

    • Try deleting by halves - first the left half and then, if the error persists, delete the top half of the remaining drawing, and so on.

    • Use the Edit Area  tool to quickly delete all objects in a particular area.

    • Sometimes it is helpful to close the "Trash" plan without saving your work and then reopen it and start your search again.

  4. When you discover where the problem object is found, make a note of its location and close the "Trash" plan.  DO NOT save the changes you made.  If you find that you need to continue searching, it will be helpful if this drawing is still intact.


To correct the problem

  1. Open original plan and locate the problem object that you found in the "Trash" copy of the drawing.

  2. Once the object is located, you can do one of two things:

    • Edit the object's shape using its edit handles to correct the problem. 

    • Select, delete, and then replace the object.  Often, this is the best approach because it removes any permanent problems that might have become associated with the object.