Creating a Dormer in a Roof with Multiple Pitches

QUESTION

I am designing a Dutch Colonial gambrel roof with dormers. I can't use the Dormer Tools because the roof has more than one pitch, so what do I need to do? 

ANSWER

One of the components of an automatic dormer is a Roof Hole, which by definition must always be placed in a single roof plane. When a dormer needs to span more than one roof plane, as it does in a gambrel roof, it must be drawn manually. 

To draw the dormer walls

1. Access the plan in which you would like to add a dormer to a roof with multiple pitches.  
   
   In this example, a 30' x 40' single story structure with a roof with three different pitches is used.  
   
   
   
   
   
   
2. Select Build> Floor> Build New Floor  from the menu, select Derive new 2nd floor plan from the 1st floor plan, and click OK 
   
   
   
3. In the 2nd Floor Defaults make any desired changes to your structure and finishes, and click OK to create a 2nd floor based on the first floor plan.  
   
   
   
4. It's likely that you're using manual roofs, which means that your roof planes will not automatically display on Floor 2. We can make them display on Floor 2 by using the Display on Floor Above  edit tool.
   
   
   
   
   • Go Down One Floor  to Floor 1.
     
     
   • While holding the Ctrl/Command key and using the Select Objects  tool, click on each roof plane until they're all selected.
     
     
   • Use the Display on Floor Above  edit tool to move the display of these roof planes onto Floor 2. This will not affect the 3D position of the roof planes. 
     
     
   • Go Up One Floor  to Floor 2.
   
   

   On the new Floor 2, notice the dashed lines that run parallel to the roof ridge. These are ceiling break lines, which represent the division between the flat, full-height ceiling and the angled, lower ceiling under the roof.  

   
   
5. Select Build> Wall> Straight Interior Wall  from the menu, then click and drag to draw an interior wall parallel to the ceiling break lines.
   
   Do not try to position it accurately as you draw - it can be moved into position precisely in a moment.
   
   

   Knee walls typically have unused attic space on one side. If you would like, you can create a custom wall type with only one sheetrock layer. For more information on creating exposed studs please see the Related Articles section.

   
   
   
   
   
6. Click on the newly drawn wall to select it, then use the Open Object  edit tool to display the Wall Specification dialog.
   
   
   
7. On the Roof panel, check the Knee Wall box, then click OK.
   
   
   
8. With the wall still selected, select the Temporary Dimension  and input how far you'd like this wall to be from the exterior wall.
   
   In this example 78" is used so that the wall is inline with the ceiling beak line.
   
   

   If you do not see Temporary Dimensions, enable them by going to View> Temporary Dimensions.

   
   
   
   
   
9. Select Build> Wall> Straight Exterior Wall  from the menu, then click and drag to draw the front and two side walls of the dormer.  
   
   
   • Draw the walls sequentially in a clockwise direction to make sure that the siding material displays on the outside of the structure.  
     
     
   • If the siding material is facing inwards, Select  the wall and use the Reverse Layers  edit tool to flip the wall.
   
   
   
10. Use dimensions to accurately position the dormer walls relative to the larger structure.   
    
    In this example, the side walls are three feet away from the exterior side walls and the front wall is one foot from the front exterior wall.  
    
    
    
    
    
    
11. Using the Select Objects  tool, click in the room formed by the knee wall, dormer walls, and exterior walls to select it and use the Open Object  edit tool to display the Room Specification dialog.
    
    
    
12. On the General panel, select "Attic" from the Room Type drop-down list, then click OK.
    
    
    
13. Select  the interior knee wall, then use the Add Break  edit tool to add a break to the left and right wall intersections.
    
    
    
14. Using the Select Objects  tool, click on the middle section of knee wall and Delete  it.
    
     
    
    
    
15. If you want dormers on both sides of the structure, repeat this process on the other side of the design.
    
    

The dormer walls are now in place, but the roof above them prevents them from extending upward. You can now edit the roof planes so that they accommodate the dormer.

To notch the lower roof around the dormer

1. Zoom  in on one of the front corners of the dormer so that you can clearly see the dormer walls and roof planes.
   
   
   
2. Using the Select Objects  tool, click on the roof eave closest to the dormer walls to select it.
   
   
   
3. Use the Add Break edit tool, then click over the back edge of the roof plane, near the outside edge of the dormer side wall.
   
   

   When your pointer is over the intersection of the two, a red, square Endpoint Snap Indicator will display at the intersection.  
   
   If you do not see this Snap Indicator, go to Edit> Snap Settings, and make sure that Object Snaps and Endpoint Snaps are enabled.  

   
   
   
   
   
4. Repeat Step 3 on the other side of the dormer.
   
   
   
5. With the eave roof plane still selected, Zoom Out  as needed, select the new edge created between the two breaks that you added and drag it towards the outside of the dormer front wall.  
   
   In the image below, the eave roof plane is shown with a green fill to better illustrate its final shape.
   
   
   
   

To divide the middle roof plane in two

1. Click on the middle roof plane to select it, then use its edit handles to pull one side back until it snaps to just one side of the dormer.
   
   When the roof plane edge reaches the outside of the dormer side wall, the On Object  snap indicator will display. Release the mouse button to snap the roof plane edge to the outside of the dormer wall.  
   
   In the image below, the resulting roof plan is shown with a green fill to better illustrate its size and shape.
   
   
   
   
   
2. With the roof plane still selected, select the Copy/Paste  edit tool, then click on the Reflect About Object  edit tool.
   
   
   
3. Hover your cursor vertically in the middle of the room and click to create a copy of the roof plane on the other side of the dormer. 
   
   
   
   

To extend the upper roof plane over the dormer

1. Select the upper roof plane, use the Add Break edit tool, then select the Sticky Mode edit tool.
   
   
   
2. Position your cursor over the front edge of the roof plane, outside one of the dormer side walls, and click once at that location, and once on the other side of the dormer.  
   
   
   
3. Use the Select Objects  tool to select the new edge created between the two breaks that you added, and drag it past the outside of the dormer front wall.  
   
   
   
   
   
4. Select and drag each of the roof plane edges that run parallel to the dormer side walls as needed to produce the desired overhangs.  
   
   In the image below, the roof plane is shown with a green fill to better illustrate its final shape.
   
   
   
   
   
5. Create a Full Overview  to see the results.  
   
   
   
   

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