Duravent Stove Pipe DuraTech Roof Flashing Adj 7/12-12/12, 5

Select the DuraTech roof flashing by measuring the pitch of the roof at the chimney penetration location. Roof pitch is expressed as a ratio of vertical rise to horizontal run — for example, a 9/12 pitch rises 9 inches for every 12 horizontal inches. Measure the pitch using a level or pitch gauge placed against the roof surface at the penetration point. If the pitch falls between 7/12 and 12/12 inclusive, the 5DT-F12 is the correct flashing. If the pitch is 6/12 or shallower — including a flat roof — use the 5DT-F6. If the pitch is 13/12 or steeper, use the 5DT-F18. Measuring the pitch at the actual chimney penetration point is important because roof pitch can vary in complex roof geometries with multiple slopes or dormers. Selecting a flashing outside the correct pitch range results in a poor fit that cannot form a properly sealed weathertight installation.

DuraVent specifies aluminum for the DuraTech 5-inch through 8-inch roof flashings and galvalume or other materials for the larger diameter and some other configurations. Aluminum offers excellent weather corrosion resistance, long service life when exposed to outdoor precipitation and UV exposure, and good formability for the complex cone and base shapes required in roof flashings. For the steeper pitch range of the 5DT-F12 — 7/12 through 12/12 — the flashing base must be formed at a more pronounced angle to sit flush against the steeply sloped roof surface, and aluminum's formability supports this geometry. Both aluminum and galvalume are well-proven roofing flashing materials in residential construction, and either material provides the weather resistance required for long-term service when correctly installed and integrated with the surrounding roofing materials.

The 5DT-F12 covers the pitch range up to and including 12/12 — a 45-degree slope where the roof rises an equal distance vertically as it runs horizontally. Roofs steeper than 12/12 are relatively uncommon in standard residential construction but do appear in steep architectural styles, some historic buildings, and certain regional construction traditions. For pitches from 13/12 through 18/12, the 5DT-F18 is the appropriate DuraTech 5-inch flashing. Using the 5DT-F12 on a roof steeper than 12/12 would result in the flashing base not sitting flush against the roof surface, preventing a proper seal and creating a high risk of water infiltration at the roof penetration. Always confirm the roof pitch at the penetration point against the selected flashing's rated pitch range before ordering.

Steeper roof pitches affect two aspects of the DuraTech chimney installation above the roofline. First, a steeper pitch reduces the horizontal footprint of the roof relative to the chimney height, which generally means the chimney extends further above the roof surface for a given vertical height above the penetration — the building code minimum of 3 feet above the roof penetration and 2 feet above any portion of the building within 10 feet of the chimney still applies regardless of pitch. Second, the DuraTech installation instructions specify that when the chimney extends more than approximately 4 to 5 feet above the roof penetration, the 5DT-XRS extended roof bracket is required to brace the exposed chimney section against wind loads. On a steep pitch roof, the relatively larger exposed chimney section above the roofline may reach the bracket requirement threshold more quickly than on a low-pitch roof for the same absolute chimney height.

The 5DT-F12 flashing base is installed on the roof deck around the chimney penetration opening, with the flat base portion overlapping the surrounding roofing material. On shingled roofs, the base is integrated with the shingles following standard step-flashing and counter-flashing techniques — shingles course over the top portion of the flashing base and under the bottom portion, directing water away from the penetration. The flashing base is secured to the roof deck and sealed at its edges with appropriate roofing sealant or caulk per local roofing practice and the DuraTech installation instructions. Above the base, the cone portion of the flashing rises around the chimney pipe, and the storm collar — the 5DT-SC — installs on the chimney pipe above the top of the cone and is sealed to complete the weather-tight barrier between the flashing and the pipe.

Above the 5DT-F12 roof flashing, the complete DuraTech 5-inch exterior roof termination requires the 5DT-SC storm collar on the chimney pipe immediately above the flashing cone, sealed with high-temperature sealant, followed by the required pipe sections extending the chimney at least 3 feet above the roof penetration and at least 2 feet above any portion of the building within 10 feet, and a chimney cap at the top to prevent weather and debris from entering the flue while allowing flue gases to exit freely. When the chimney extends more than 4 to 5 feet above the roof penetration, the 5DT-XRS extended roof bracket provides structural bracing for the exposed section against wind loads. The locking band 5DT-LB may optionally be applied to joints in the above-roof section for additional joint security.