Duravent Stove Pipe DuraTech Ceiling Support Box, 5" x 24"

The 5DT-CS24 ceiling support box performs two essential functions simultaneously. First, it provides the structural support that carries the full weight of all chimney pipe sections above it in the installation — the support box is anchored to the ceiling framing and transfers the chimney load into the building structure, allowing the chimney run above to be self-supporting from this point. Second, it provides the code-required fire separation at the ceiling or floor penetration point, replacing the need for the separate 5DT-FRS Firestop Radiation Shield at that penetration location. Because the support box serves both functions at a single penetration, it is generally used at the primary ceiling penetration where structural support is required, while the 5DT-FRS is used at intermediate penetrations where structural support is not needed.

The 24-inch height of the 5DT-CS24 refers to the total height of the support box assembly, which determines how deep a ceiling or floor assembly the box can accommodate. The appropriate support box height is selected based on the depth of the ceiling or floor framing assembly at the penetration point — the support box must be deep enough to span the full depth of the framing from the bottom of the ceiling to the top of the floor above, plus any additional height required for a cathedral or A-Frame ceiling application. DuraTech ceiling support boxes are available in different heights for standard depth and deeper ceiling assemblies, and the correct height must be selected to match the specific ceiling construction at the installation site.

The bottom of the DuraTech support box is designed for connection to the DuraTech chimney system's twist-lock interface. DVL and DuraBlack are different stovepipe connector systems — DVL is a double-wall close-clearance connector stovepipe and DuraBlack is a single-wall black connector stovepipe — both of which use different connection geometries than the DuraTech twist-lock system. A dedicated adapter is required at the bottom of the support box to provide the mechanical transition between the DVL or DuraBlack stovepipe from the appliance and the DuraTech chimney system's connection interface at the support box. The appropriate adapter must be selected to match the specific stovepipe system being used to connect the appliance to the chimney.

Yes. The 5DT-CS24 is specifically confirmed as suitable for both flat and cathedral — A-Frame — ceiling applications. In a cathedral ceiling application, the ceiling framing members are angled rather than horizontal, and the support box must be installed at an angle through the angled ceiling framing to allow the chimney pipe to pass through vertically. The DuraTech installation instructions provide specific guidance on how to correctly install the ceiling support box in a cathedral ceiling configuration to maintain the required chimney pipe alignment and clearances in this more complex framing geometry.

The DuraTech installation instructions specify that the Attic Insulation Shield must be used in all installations that pass through an attic regardless of whether a support box or firestop radiation shield is used at the penetration. When the 5DT-CS24 is used in a short attic space as noted in the installation instructions, the 5DT-IS Attic Insulation Shield fits over the support box and provides the required insulation exclusion zone above the support box in the attic space, preventing attic insulation and debris from accumulating against the chimney pipe. The 5DT-IS requirement applies whether the support box or the 5DT-FRS is used at the attic floor level.

The 2-inch wide trim collar is a decorative finishing ring that installs at the interior ceiling surface around the support box opening, providing a clean finished appearance at the point where the chimney exits through the ceiling into the room below. The trim collar covers the gap between the edge of the support box and the surrounding ceiling surface, concealing the rough framing opening edges and providing a neat, professional finish at the ceiling penetration point. It is painted black to match the support box and the other visible DuraTech components in the installation. The trim collar is included with the support box and does not need to be ordered separately.