A prefab chimney is not a masonry chimney. prefab chimneys are used to eliminate the time it takes to build a chimney out of brick. Prefab chimneys are made in a factory and assembled on the site where it is to be installed.
DOES MY HOME HAVE A PREFAB CHIMNEY?
If your home does not have a visible masonry or brick structure, you most likely have a prefab chimney
PREFAB CHIMNEY SERVICE
If you need service or repairs on your prefab chimney