Exterior Chimney Chase Construction

Above the chase height as per manufacturer.

Exterior chimney chase construction.

Keep minimum clearance from pipe to combustibles. If your home has a wood chimney chase with wood lap siding you need to pay special attention to it. Frame the walls on the roof assemble 2 together then stand each set and nail off corners of last two joints. 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.

Crickets are more reliable particularly in climates where snow can accumulate and lead to ice dams. For wind resistance if the chimney chase is passing through the roof structure rather than abutting the roof structure end it should be framed continuously through the roof structure not simply tacked on top of the roof sheathing. Fire stop at attic and roof deck. Framing the chimney chase.

Typically uses 2x4 structural members sheathed with osb or plywood exterior building sheathing. Frame the chase so the bottom of the vent is. But a rot problem would better be blamed on construction or flashing errors that allowed leaks into the chase. The exterior of the chimney may require tuckpointing or replacement of siding materials to provide the best protection against moisture intrusion into the roof and interior structural materials.

There are a disproportionate number of wood chimneys with rotted siding and wall sheathing when compared to other types of siding and other locations. Chimney chase a fireplace chase is essentially a knock out area of structure that hides a metal fireplace or cement blocks in a fireplace.