doing some work on a chimney. There is evidence of streaks on walls in basement coming from the chimney. There isn't a cap on the chimney but someone has said no need. Is there a specific size need to cover the opening to stop water/ birds from entering???The flashing at the base of the chimney will be retared along with the bricks will be repointed. ???is a cap really necessary???
Chimney caps aren't required but they do offer a lot of advantages. They protect the masonry and cement parging from water freeze damage as well as keep out rain and varmints. I designed mine the same size as the outside chimney masonry and 12" higher than the flue. It is open on all four sides but has 1/4" x 1/4" hot dip galvanized hardware cloth in the openings to keep out racoons and birds. The cap itself is made of 22 ga. galvanized sheet metal.