Exterior Chimney Chase Construction

Keep minimum clearance from pipe to combustibles.

Exterior chimney chase construction.

Typically uses 2x4 structural members sheathed with osb or plywood exterior building sheathing. 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. Above the chase height as per manufacturer. Crickets are more reliable particularly in climates where snow can accumulate and lead to ice dams.

If your home has a wood chimney chase with wood lap siding you need to pay special attention to it. Frame the chase so the bottom of the vent is. Fire stop at attic and roof deck. Build chase of fireplace just like any other wall structure by placing its uprights between plates and top plates to create a large box.

Wood siding on chimneys wood shingles are often used as siding material for chimneys continuing from the roof area. Framing the chimney chase. There are a disproportionate number of wood chimneys with rotted siding and wall sheathing when compared to other types of siding and other locations. 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.

Right since the chimney chase carries an insulated metal flue rated for zero clearance possibly actually requiring an inch or more of airspace and because the chase is outside the building it s not normally insulated. 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.