Insulbrick. Insulbrick or Inselbrick (the product tradename) is an exterior siding product that mimics brick. The owners of the church building in this picture, located in the 900 block of Shelby Street, probably applied their insulbrick siding in the 1930s or 1940s, not long after the asphalt and fiber siding came on the market. Mass produced and inexpensive, insulbrick came in a variety of brick-like colors and was touted as an insulating material—the product name was a no-brainer.