Building A Wood Chimney Chase

Chimney chase a fireplace chase is essentially a knock out area of structure that hides a metal fireplace or cement blocks in a fireplace.

Building a wood chimney chase.

Make the chase enclosure airtight chimneys built on an outside wall whether exposed or boxed with a chase are prone to backdrafting. Called kickouts these keep water from running behind the cladding below and into the wall assembly see images 1 2. Typically uses 2x4 structural members sheathed with osb or plywood exterior. Nfpa 211 reduces fire hazards by ensuring the safe removal of flue gases the proper installation of solid fuel burning appliances and the correct construction and installation of chimneys fireplaces and venting systems.

Kickout flashings we always install diverter flashings wherever a roof intersects a wall. Framing the chimney chase. For chimney chases built into gable walls we install a partial diverter see image 2 again extending the sloped surface several inches beyond the corner see image 3. Codes allow a maximum of 90 degf temperature rise above ambient inside the the chimney chase well below the combustion or pyrolysis point for plywood.

Now that the frame has been completed guess who gets to clean up all that mess. To build a fire retardant chimney chase one might use fire retardant plywood and sure one could try spraying a fire retardant coating but those are not common practices.