Masonry Chimneys 

Chimney Cap  --spark arrestor /rain guard

This device keeps weather and pests out of your chimney and for solid fuel appliances it  prevents large embers from exiting the chimney during operation.

This is most commonly referred to as a chimney cap.

There are also caps that are made to cover multiple flues in a chimney system these are called multiflue caps

Mortar Cap    --splay wash / crown wash 

Splay Wash is a topping of a cementitious product that slopes away from the center of the chimney to the edges of the chimney 

Crown Wash is a concrete top that overhangs the chimney construction and sheds water away from the structure.

Flashing  

Chimney flashing is the barrier between the home structure and the chimney whose intended function is to prevent water  entering from that area found at ropy lines.

Flashing consists of 2 levels. The first being step flashing which is integrated into the roofing material and counter flashing which should be all metallic with very little sealant. 

Crickets are small dormers that are required in certain circumstances to shed water, snow and ice, and debris away from chimneys.

Chimney Height   --  3-2-10 rule 

Chimneys are required to be a minimum of 3 feet above the roof and 2 feet higher than any portion of the building within 10 feet 

Chimney Construction 

Masonry chimneys can be constructed out of brick, cement block, stone poured concrete or other masonry materials. Chimneys are required to have 4 walls and are required to be at least 4 inches thick ( except stone construction which is required to be thicker) .