roof that slopes away from the ridge in two successive planes).

The mansard is a curb hip roof, with slopes on all sides of the building, and the gambrel is a curb gable roof, with slopes on only two sides. The curb is a horizontal, heavy timber directly under the intersection of the two roof surfaces. A significant difference between the two, for snow loading and water drainage, is that, when seen from above, gambrel roofs culminate in a long crease at the main ridge