Although Ietada subsequently took part in many battles, his main occupation was with the construction and maintenance of castles, such as Hamamatsu-jo Castle, Makino-jo Castle (Suwahara-jo Castle, the Province of Totomi), Shinjo-jo Castle, Yokosuka-jo Castle, the tsukejiro (outposts) of Takatenjin-jo Castle, and the like; therefore, it is assumed that he was skilled in civil engineering.
その後、家忠は各地の合戦に従軍するが、合戦そのものよりも浜松城・牧野城（諏訪原城）・新城城・横須賀城、また高天神城攻めの付城（前線基地）などの城郭の普請や補修などに従事しており、土木に技能を持っていたことがうかがえる。