Best Chimney Flashing for a Flat Roof (2026): 4 Picks Compared

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Specifications are manufacturer rated, collected 22 October 2026. Two of the four state a warranty term.

How we scored them

Each flashing is scored out of 10 on performance, build, value, safety and warranty, using only what the listing publishes. The weights are on our How We Pick page. For flashing, safety means a stated safety certification or chimney rating; only the DuraVent states a 2100°F H Class A rating, so the others score zero there. Two listings state a warranty term: Sobalai at 2 years and DuraVent with a limited lifetime warranty.

Scores run from 9.2 to 9.8: each product’s point total is placed on that range, so more points always means a higher score.

Buying guide: the best chimney flashing for a flat roof

Start with the pipe diameter

Measure the outside diameter of the pipe before anything else. The VIVIDA #7 fits 6 to 11 inch pipe, the Sobalai #9 fits 10 to 18 inch pipe, and the DuraVent 9049V is a 6-inch flashing. Both silicone boots have marked cut lines so you trim the boot to the pipe, but the listing warns not to over-tighten the screws. The Therwen sheets are 5 x 7 inch flashing plates, not a pipe boot, so they suit patching around a chimney or skylight rather than sealing a round pipe.

Pitch decides the pick

A flat roof is 0/12 pitch, and only one listing here names it: the DuraVent 9049V adjusts from 0/12 to 6/12, which covers flat and low-slope roofs. The VIVIDA states it suits 10/12 to 12/12 pitch metal roofs with a square base, and the Sobalai describes a square base for corrugated metal roofs. On a truly flat roof, a boot shaped for a steep ribbed roof will not sit flat, so match the pitch range on the listing to your roof. Our best chimney flashing for a metal roof roundup covers the pitched-roof side.

To check your own roof, note the rise over a 12-inch run: a flat roof reads 0/12, which is exactly what the DuraVent adjustment starts at. If the roof has even a slight slope for drainage, the 0/12 to 6/12 range still covers it. For the square-base boots, confirm the base can sit flat on your roofing material; the Sobalai base is 24.8 inches square, so it needs a clear flat area that big around the pipe.

Temperature ratings, stated plainly

The VIVIDA states a range of minus 165.2°F to 446°F, the Sobalai states a maximum of plus 500°F and a minimum of minus 100°F, and the DuraVent states a 2100°F H Class A chimney rating. The Therwen sheets state no temperature rating. Match the rating to the flue: a wood stove pipe runs hotter than a furnace vent, and the DuraVent rating is the only one stated as a chimney class. This site does not give chimney installation steps; a certified pro and the local code decide the final call. As a rule of thumb for comparing listings, a wider stated range costs nothing extra here: the Sobalai covers minus 100 to plus 500 degrees F, which spans both furnace vents and wood stove pipes on paper, while the VIVIDA range tops out at 446 degrees F.

Silicone boot vs flashing sheets

Three picks are pipe boots and one is not. The VIVIDA and Sobalai are silicone boots that slide over the pipe and seal to the roof with a square base, while the DuraVent is a metal flashing that adjusts to the pitch. The Therwen sheets are flat aluminum plates for step flashing and patching around chimneys and skylights. If the job is a round pipe through the roof, pick a boot or the adjustable flashing; if the job is sealing the sides of a masonry chimney where it meets the roof, sheets are the right form.

Base size and what comes in the box

The Sobalai square base measures 24.8 by 24.8 inches and 7.8 inches high, and the box includes 50 roofing screws and 2 hex bit sockets. The VIVIDA ships its #7 boot with 25 roofing screws and an 8mm hex bit socket. The DuraVent lists no fasteners in its included components, and the Therwen box holds 40 aluminum sheets at 1.72 lb total. Count the fasteners against the perimeter you need to seal; a big square base needs more screws than a small one. Pair the flashing with a bead of sealant made for the job . see our best stove pipe sealant picks.

Around the Woodpile

• Measure the pipe outside diameter first: 6 to 11 inches for the VIVIDA, 10 to 18 inches for the Sobalai, 6 inches for the DuraVent.
• Keep the fasteners with the boot: 25 screws and one hex socket with the VIVIDA, 50 screws and two hex sockets with the Sobalai.
• The Therwen sheets cut with tin snips per the listing; note the listing says the aluminum surface blackens after long rain exposure and needs timely replacement.
• Chimney work is not a DIY walkthrough here: have a certified pro confirm the flashing against the local code before the first fire.
• Check the box on arrival: one boot, 25 screws and a hex socket for the VIVIDA; one boot, 50 screws and two hex sockets for the Sobalai; 40 sheets for the Therwen.

Frequently Asked Questions

What size flashing do I need for my chimney pipe?

Measure the pipe outside diameter. The VIVIDA #7 fits 6 to 11 inches, the Sobalai #9 fits 10 to 18 inches, and the DuraVent 9049V is made for 6-inch pipe. Trim the silicone boots on the marked cut lines to the measured size.

Can I use a metal-roof boot on a flat roof?

The VIVIDA and Sobalai listings describe corrugated and metal roofs, with the VIVIDA naming 10/12 to 12/12 pitches. The DuraVent 9049V adjusts from 0/12 to 6/12, which covers a flat roof. When in doubt, have a certified pro confirm the fit.

What temperature ratings do these listings state?

VIVIDA states minus 165.2°F to 446°F, Sobalai states plus 500°F maximum and minus 100°F minimum, and DuraVent states a 2100°F H Class A chimney rating. The Therwen sheets state no temperature rating.

Will a silicone boot last on a flat roof?

The listings do not state service life. The Sobalai listing claims UV resistance, anti-oxidation and anti-corrosion without cracking, and the VIVIDA describes its silicone as weather-resistant, but neither gives a year figure. The only stated warranties are the Sobalai 2 year term and the DuraVent limited lifetime term.

Do any of these state a warranty?

The Sobalai listing states a 2 year warranty and the DuraVent listing states a limited lifetime warranty. The VIVIDA and Therwen listings state no warranty term.

How many pieces come in the box?

The VIVIDA ships one boot with 25 screws and one hex socket, the Sobalai ships one boot with 50 screws and two hex sockets, and the Therwen ships 40 aluminum sheets. The DuraVent lists no fasteners.

Related guides

See the stove accessories hub and best chimney flashing for a metal roof, then compare with the best chimney flashing for a slate roof or the best flashing for brick chimney.

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