Abstract: The present invention concerns a computer-implemented method, a computer system and a computer program product for direct room modeling in a CAD model. The CAD model comprises a rectangular coordinate system comprising mutually orthogonal height, first horizontal and second horizontal directions. A first position and subsequently a second position within the model are obtained via a user input device. The first and second positions define a rectangle perpendicular to the height direction and aligned with the horizontal directions. The rectangle comprises edges and corners. The rectangle comprises the first and second positions at diagonally opposite corners. A room drawing operation is automatically performed based on the rectangle. One or more walls and/or wall portions, each extending in the height direction and along an edge of the rectangle over in essence the full length of the edge, are thereby inserted or removed.