Loomis was born January 28, 1859 in Westfield, Massachusetts to Dr. John Loomis and Clarissa Loomis née Robinson. Just before the American Civil War, Dr. John Loomis moved with his family to Jeffersonville, Indiana, where they stayed until about 1910, when they moved to Louisville.
Loomis designed the Carnegie Library in Warder Park, in Jeffersonville, Indiana, from which he was a native. He also designed the Conrad-Caldwell House, a contributing property in the St. James-Belgravia Historic District in Old Louisville.
A number of buildings that Loomis or the firm designed survive and are listed on the U.S. National Register of Historic Places. These include: