Drawing Manual Dormers in a Gable Roof

To create dormers in an attic, create a new floor for your plan and modify this floor with knee walls and windows to form gables. We'll start with a new 40 x 30 foot plan to learn this technique.

To create a new plan

Select File> Close All from the menu to close any open plans.

Select File> New Plan to open a new plan.

Draw a rectangular floor plan, 40 feet by 30 feet, in a clockwise direction.

Click the Fill Window Building Only

button to zoom in on the house.

Select File> Save

from the menu and give the plan a name.

Group select the right and left vertical walls, open them for specification, and on the Roof tab of the Wall Specification dialog, click the Full Gable Wall check box and click OK.

Select Build> Floor> Build New Floor

Check the Derive new 2nd floor plan from 1st floor plan option in the New Floor dialog and click OK.

Group select the right and left vertical walls on the second floor, open them for specification, and on the Roof tab of the Wall Specification dialog, click the Full Gable Wall check box and click OK.

Select Build> Roof> Build Roof

to open the Build Roof dialog. Change the roof pitch to 12 in 12 and click OK.

To create two knee walls

A knee wall is a short wall on an upper floor that is cut off by a roof plane. Select Build> Wall> Interior Wall

and draw a horizontal interior wall (from left to right). Position this knee wall so that it is 5 feet from the top exterior wall.

Draw another interior wall (from right to left) and position it 5 feet from the bottom exterior wall. You can reposition the knee walls using dimensions. For more information, see "Moving Objects Using Dimensions".

Group select both interior walls and open them for specification. Check Knee Wall on the Roof tab of the Wall Specification dialog and click OK.

Click the Dimension Tools

parent button, then the Automatic Exterior Dimensions

tool to display exterior dimension lines for your plan, which should now look like this:

To build the dormer walls

Select Build> Wall> Exterior Wall

and draw two rectangular boxes on the outside of the lower interior wall, as shown in the following image.

Position the lower walls of each dormer box 2 feet from the bottom wall. The lower dormer walls are those parallel to the bottom wall.

Edit each dormer box so that it is 6 feet from each vertical side wall and 8 feet wide.

Select Build> Wall> Break Wall

and click along the lower interior wall to place wall breaks as shown in the following image.

Delete the upper, horizontal portion of each window box.

To add a window to each dormer

Select Build> Window> Window

and click on each dormer front wall to place a window. The program will warn you that that you are adding windows to an interior wall; click OK to continue.

Select the window; click the Center Object

edit button; and click on the wall containing the window to center it on the wall.

Do the same for the other window.

To build the roof

Group select the two dormer front walls that contain a window, open them for specification, and on the Roof tab of the Wall Specification dialog, check Full Gable Wall and click OK.

Group select the dormer side walls, open them for specification, and on the Roof tab of the Wall Specification dialog, specify the Pitch for the dormer roof plane above the wall, and click OK. Earlier we specified a pitch of 12 in 12 in the Buld Roof dialog, that pitch should have prefilled here. A steep pitch of 12 in 12 will work well for these dormers.

Double-click the narrow room above the top knee wall to open the Room Specification dialog, designate its Room Type as "Attic"and click OK.

Do the same for the lower attic room.

Select Build> Roof> Build Roof

from the menu.

In the Build Roof dialog, check Build Roof Planes and click OK.

Select 3D> Create Render View> Render Full Overview

Notice there are small gaps in the dormer side walls. This gap is caused by the difference between the position of the knee walls and the point at which the ceiling intersects the roofplane. This location is marked by the dotted line in floor plan view.

Select each of the knee walls and move them back so that they are in alignment with the ceiling plane. Making sure the knee walls are coplanar can be accomplished using Object Snaps

Take a look in a 3D view.