Insulbrick is fiberboard sheathing coated with tar and added granular material, similar to asphalt shingles. The surface is stamped with a brick or stone pattern. As a rule, tarpaper and Insulbrick were applied over wood siding. Insulbrick was the preferred choice for replacement siding until aluminum and vinyl siding became available in the late 1950s. Asphalt siding was available from the 1930s to about 1960. Many people think of it as a cheap replacement siding.

Typical issues with this siding are environmental wear and mechanical damage. The material like singles is expected to last approximately 20-25 years. When the material deteriorates or is penetrated water may enter and attack the fiberboard substrate causing swelling and the loss of structural integrity.