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Chimneys, Flashing & Vents

Vent Boot & Stack Flashing Replacement in Toronto & the GTA

A water stain near a bathroom often traces straight up to the plumbing stack — that pipe poking through the roof. The rubber boot sealing it bakes in the sun and splits somewhere around year ten to fifteen, usually while the shingles around it still have plenty of life. It's one of the most common roof leaks in the GTA, and one of the cheapest to fix properly.

The proper fix is replacement, not a bead of caulking over the crack. We lift the shingles around the stack, remove the old flashing, and lap a new one into the courses so gravity does the waterproofing — sealant is a garnish, not the system. If you'd rather not repeat this in a decade, a silicone collar or all-metal two-piece flashing outlasts a standard neoprene vent boot by a wide margin.

This is small-job territory, and we quote it that way. If someone looks at one cracked pipe collar and quotes a roof replacement, get a second opinion. While we're up there we check the other stacks and penetrations too — they were all installed the same day, so when one rubber boot goes, its siblings are usually close behind.

What this covers

  • Removal of the shingles immediately around the stack — carefully, so most go back on
  • New vent boot or two-piece metal stack flashing lapped correctly into the shingle courses
  • Upgrade options: silicone collar or all-metal flashing that outlasts standard neoprene
  • Inspection of every other stack, boot and penetration while we're on the roof
  • Attic-side check for staining or rot on the framing around the pipe
  • Replacement shingles woven in where the originals were too brittle to reuse
  • Sealant only where sealant belongs — the laps do the waterproofing

Just need one small job done?

Replace a cracked vent boot

What affects the price

  • How many stacks need doing — the second one adds little once the setup is in place
  • Roof pitch and height, since a steep two-storey changes the safety setup
  • Shingle condition: aged, brittle shingles crack on lifting and need more replacements woven in
  • Flashing choice — standard neoprene boot, silicone collar or all-metal
  • How long the leak ran before the call; rot in the deck around the pipe adds carpentry
  • Season — cold-weather work is doable but slower, because shingles have to be warmed to bend

Every home is different, so we don’t publish flat prices — the quote is free and based on your actual job.

Common questions

Why is my plumbing vent leaking?
Almost always the rubber collar. UV exposure and freeze-thaw cycles harden the neoprene until it cracks where it grips the pipe, and water follows the pipe down into the house. The metal or plastic base usually outlives the rubber by years, which is why a roof can be leaking at a stack that looks fine from the ground.
Can I just caulk the cracked boot?
You can, and it might buy a season — but caulking over perished rubber is a patch on a patch. The sun that killed the boot goes to work on the sealant next. Given that a proper vent boot replacement is one of the smallest jobs on a roof, the honest answer is to do it once, correctly.
How long do vent boots last?
Standard neoprene boots give ten to fifteen years in Ontario sun — often less than the shingles around them, which is exactly the problem. Silicone collars and all-metal two-piece flashings routinely outlast the roof itself. If you're reshingling anyway, upgrading every stack flashing at the same time is cheap insurance.
The stain is two rooms away from the bathroom — can it still be the stack?
Yes. Water that gets in at a plumbing stack leak follows the pipe, then the framing, and surfaces wherever it finds a seam in the drywall — often nowhere near the entry point. That's why we confirm from the attic side before replacing anything, instead of assuming the stain sits under the problem.
Can this be repaired in winter?
Yes, with care. The shingles around the stack have to be warmed so they lift without snapping, and brittle ones get replaced rather than reused. If water is actively coming in, don't wait for spring — a winter fix done patiently beats months of intermittent leaking through the freeze-thaw season.

Ready to sort out your vent boot & stack flashing replacement?

Tell us what your home needs — a small fix or a full project — and get a free quote.

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