Chimneys, vents and flashing on a metal roof
Metal Roofs · 5 min read ·
The panels shed water fine on their own; the risk is wherever something breaks through them. A brick chimney gets metal flashing bent tight to the brick on every side, a vent pipe gets a boot, and joints between roof sections get trim.
Water finds the interruptions
A sheet of metal running from eave to ridge has no seams for rain to work into along its length. The trouble spots are the interruptions: a chimney sitting in the middle of a slope, a plumbing vent, a lower roof butting into a taller wall.
Each of those needs its own piece of metal shaped to send water around the obstacle and back onto the panels. Get those right and a metal roof is simple. Rush them and you have a leak with a nice roof around it.
The brick chimney on the black roof
On the black metal-over-shingle job from May and June 2026, the chimney got its own flashing fitted tight against the brick on the front and both sides. The hero photo shows the front piece: a bent metal apron lying against the bottom courses of brick and lapping onto the black panels below.
The side pieces run up the slope along the brick, turned up against the masonry and down onto the panels. Water coming down the roof meets the chimney, gets pushed to either side, and keeps moving.
Other chimneys, other roofs
On the gray metal job the battens were worked around the brick chimney on the first day, so the gray panels that followed had backing right up to the masonry when they were fitted around it. The red job also had its panels fitted around a chimney.
Tall chimneys add an access problem. On the downtown Kittanning building we used a boom lift to reach the top of a brick chimney three stories up. Our commercial roof write-up covers that job in full.
Vent pipes get a boot
Plumbing vents are small, but they are a hole straight through the roof. On the red metal-over-shingle roof a vent pipe comes up through the panels with its own boot, a flexible collar that seals around the pipe and sits down on the ribs of the metal.
We bring the pipe through first and fit the boot as the panels go on around it. Retrofitting one after the fact is possible, but it is harder to get right.
Joints, hips and ridges
Where two roof planes meet, you need a cover piece. On the black job, trim covers the joint where a lower roof section meets the main roof. On the red job, hip caps were set along the peaks where sections meet at an angle, and ridge caps ran along the top.
Here is the short list of what gets its own piece of metal on our metal roofs:
What we check before quoting
At the site visit we count every chimney, vent, skylight and roof-to-wall joint, because each one adds work. We also look at the condition of the chimney itself. Loose or crumbling brick at the top is worth dealing with before new flashing gets tied to it.
Shingle roofs have their own version of all this. See our post on valleys and flashing for how we handle the same spots under shingles.
Questions
How is a chimney flashed on a metal roof?
On a metal roof, a chimney is flashed with metal pieces bent to fit tight against the brick and lap down onto the roof panels. Schaub and Sons fitted flashing to the front and both sides of a brick chimney on a black metal roof in 2026, so water running down the roof is pushed around the chimney and back onto the panels.
What is a vent boot on a metal roof?
A vent boot on a metal roof is a flexible collar that seals around a plumbing vent pipe where it comes up through the panels and sits down on the ribs of the metal. Schaub and Sons installed a vent boot on a red metal roof in June 2026, fitting it as the panels went on around the pipe.
Where do metal roofs usually leak?
Metal roofs usually leak where something interrupts the panels rather than in the middle of a sheet. The common spots are chimneys, vent pipes, skylights, and joints where a lower roof meets a main roof or a wall. Schaub and Sons flashes chimneys, boots vent pipes and trims roof joints on every metal roof it installs.
Can you reach a tall chimney when putting a metal roof on a three-story building?
Yes. On a three-story brick commercial building in downtown Kittanning in September 2026, Schaub and Sons used a boom lift to reach the eaves and the top of the brick chimney, set scaffolding along the walls, and kept the crew tied off on rope lines while working the steep metal roof.
