The Dormer tool is used to add a dormer to an existing roof. A dormer is a small structure that projects out from a sloped roof and usually includes a window. It brings natural light into upper rooms, such as an attic or loft, and also adds visual detail to the outside of the house. For example, if you want more light and headroom in an upstairs bedroom, adding a dormer is a great option.

To use the Dormer tool, go to the Roof tab in the main toolbar and select it. Then click directly on the roof surface where you want the dormer to appear. The software will automatically create the dormer and cut an opening in the roof. You can adjust the width, height, and pitch (roof slope) in the Properties panel. After placing it, you can fine-tune its style and apply different materials and colors in the 3D view to match the rest of your home design.