Drawing a trapezoidal dormer

• This requires a shed dormer, which serves as the basis.

  Drawing a shed dormer

• In plan view, draw the outline of the trapezoidal dormer in construction-line format.
  

  

  Fig.: Outline of the trapezoidal dormer in construction line format

To draw a trapezoidal dormer

Note: The two planes at the sides of the shed dormer are two pairs of custom reference planes.

1. Click Custom Planes (How).
   

   Activate Custom Planes in one of the following ways

   • Menu bar: Create Architecture General: Roofs, Planes, Sections

   • Palette: Tools Create area in the following module(s):

   General: Roofs, Planes, Sections

2. Click Properties and enter the parameters for the custom pair of reference planes.
3. Define the following parameters for the bottom plane:
   • You can set the height of the bottom plane relative to the height value of the roof’s bottom level (e.g. Lower Parallel Datum = 0.00). The bottom plane extends parallel to the datum level at an absolute height of 0.00.
4. Define the following parameters for the top plane:
   • In the Custom Reference Planes dialog box, in the Upper plane area, click Upper Plane Free.
     The Definition points area becomes active.
     
     Now you can enter three absolute height values to define the position of the plane to be created in 3D space:
   • Click Match.
     The Custom Reference Planes dialog box closes.
   • In plan view, click a corner of the plane to be created. The following prompt is displayed in the dialog line: Click plane to adopt height at top/Height at top.
     Enter the height value (as absolute value) of this point or click this point in elevation or isometric view.
   • The procedure is the same for the two other corners.

     

     Fig.: Entering the upper custom reference plane (plan view)
     Point 1 = height value measured in elevation or copied by clicking (including the opening height added) when you created the shed dormer
     Point 2 = height value of point where the shed dormer and the main roof intersect can be measured in elevation or isometric view or copied by clicking
     Point 3 = height value measured in elevation or copied by clicking (without addition of opening height) when you created the shed dormer

   • The Custom Reference Planes dialog box appears again and the coordinates of the corners are displayed in the Definition points area. Check the values and click OK to confirm.

     

   • After you have entered the three height values, the program prompts you to place construction point (1) for planes. Click the corners of the triangular outline of the plane.
     As soon as the polyline is closed, the pair of custom reference planes is created.
5. Repeat steps 1 to 4 for the second side of the dormer.

   The result might look like this:

   

Note: To apply a roof covering over the dormer and the main roof, it is best if you use the Slab tool. The Roof Covering tool only applies to roof frames. Pairs of custom reference planes are not affected.

Note: If you want to create a dormer that projects beyond the main roof, follow the steps described in Drawing a dormer with overhang using the Slab tool. The overhang needs to be defined separately for each plane.