Leak at a Roof Vent or Pipe: Usually a Small Repair Worth Doing Now

The homes with the most penetrations per square of roof in Greater Victoria are the multi-suite conversions of Fernwood, Vic West and Fairfield, where every added kitchen and bathroom brought a new stack or fan hood through an old roof, and the 1960s and 70s ranchers of Gordon Head, where three or four stacks and a dryer vent come up through low-slope sections that hold water against every flange. Each one is a rubber boot or a metal flashing with its own lifespan, shorter than the shingles.

Victoria's dry summers are hard on rubber: the Gonzales station records about 14 mm of rain in July and the sun cooks boots on south slopes until they split at the collar, then the October rains find the split. Exhaust hoods on slopes facing the southeast take wind-driven rain straight into the flap. In older attics a bathroom fan duct that has fallen off its hood behaves exactly like a roof leak in the ceiling below, and a roofer will check the duct before quoting for flashing.

A pipe boot is a metal or plastic base with a rubber collar that grips the plumbing stack. The base is woven into the shingles and lasts as long as they do; the collar is exposed rubber that expands in summer heat, contracts in winter, and takes full UV. Around 10 to 15 years the collar cracks where it meets the pipe, and water runs down the outside of the stack into the attic. Because the shingles around the boot still look perfect, homeowners often assume the leak is somewhere else.

The fix is a new boot, or a slip-over collar that fits above the old base when the shingles are too brittle to lift. Either is a short job on an accessible slope.

The other penetrations are metal flashings with a cap or hood, and each has a failure mode a professional may check for:

• Roof vents and turbines: the flange nails back out as the deck moves, and the upslope shingles no longer overlap the flange.
• Bathroom and kitchen hoods: the damper flap sticks open with lint or paint and wind-driven rain enters; hood seams rust.
• Dryer hoods: lint packs the flap and the duct, adding a fire concern to the leak.
• The duct in the attic: a flexible duct that has fallen off the hood, or an uninsulated duct that condenses in winter, drips at the ceiling grille and looks like a leak.
• Sealant-only repairs from a previous owner, which last a season or two.

From the hatch, with a flashlight and without stepping off the joists, look for a wet or stained line running down a stack or a vent's inner box, and for a duct lying loose. From the ground with binoculars, look at each boot for a lifted or cracked collar and at each hood for a missing flap. Note which penetration sits directly upslope of the stain inside; on a Victoria roof the drip is often a metre or two downslope of the entry point. Leave the roof itself to a roofer: penetrations sit mid-slope, where a fall is the main risk.

Because the crew minimum is $350 to $500 in our pricing model, a single boot at $250 to $600 is often bundled with anything else the roofer finds on the same visit, such as resealing other collars or re-nailing a vent. If the roof is within a couple of years of replacement, a temporary collar now and new flashings for every penetration at re-roof is the sensible sequence; every reputable replacement quote should list new boots and vents as included. If the roof is young, replace the failed boot properly and expect the others of the same age to follow within a few years.