We present a practical system to map and reconstruct multi-room indoor structures using the sensors commonly available in commodity smart phones. Our approach combines and extends state-of-the-art results to automatically generate floor plans scaled to real-world metric dimensions and to reconstruct scenes not necessarily limited to the Manhattan World assumption. In contrast to previous works, our method introduces an interactive method based on statistical indicators for refining wall orientations and a specialized merging algorithm for building the final rooms shape. The low CPU cost of the method makes it possible to support full execution by commodity smart phones, without the need of connecting them to a compute server. We demonstrate the effectiveness of our technique on a variety of multi-room indoor scenes, achieving remarkably better results than previous approaches.