To test the approach, a single catenary arch was generated using form-finding techniques and sequentially built from foam blocks. Moving forward we show the relationship between the joint valence (largest number of joined branches) of a multi-branched structure and the minimum number of robotic arms required for assembly using our initial technique. With only two robotic arms available, the technique was further developed to reduce the required number of arms per arch branch from two to one by attaching caterpillar tracks at the block supporting end effector. This allows a human to load the next block and the arm to move forward along the arch while maintaining equilibrium. Results show that robotic equilibrium scaffold free arch assembly is possible and can reduce scaffold waste and maintain the material efficiency of compression only structures. Future work will explore further applications of assistive robotics in construction replacing static construction aids with dynamic sensory feedback of equilibrium forces.