Name the Pipe Boot in the Spec, Because Its Collar Ages First

A pipe boot is the flashing that seals a plumbing vent where it passes through the roof. On many St. Louis houses it is the part of the roof where the weak point is a rubber ring rather than a sheet of metal or a shingle. The shingles can look sound for years while the collar around the pipe splits, and water then runs down the outside of the pipe into the attic and onto the ceiling below. This page is for the homeowner who has a roof quote in hand and wants the boot named on it, because a line that says only pipe flashing leaves the material to chance.

Where the boot sits and what it does

The boot has two parts. A flange lies flat on the deck under the shingles, and the shingle courses above it lap over the flange so that water running down the slope passes over the top edge instead of under it. A collar rises from the flange and grips the pipe. The collar is the sealed part. When it fails, the leak usually shows up inside the house, often near the vent pipe in a bathroom or a hallway ceiling, and sometimes as a wet spot on the attic side of the pipe before anything shows below.

Why the collar ages before the shingles

A rubber collar sits in the open at the top of the roof, and it takes the full load of St. Louis weather. In a January cold snap the rubber stiffens and loses flexibility. In a July afternoon on a south or west slope it can run much hotter than the air around it. The freeze thaw cycle keeps working the seam where the rubber meets the flange, and the sun slowly dries the rubber until fine cracks form around the top of the collar. Those cracks are often too small to see from the ground, and they do not announce themselves until water finds them. This is why a boot can need replacing while the rest of the roof still looks like it has years left in it.

The pipe itself matters too. A vent that moves a little with the house, or that was installed with a loose clamp, will work the collar every time the wind pushes on it. A boot that fits a pipe tightly on the day it was installed can loosen over several seasons if the pipe is not held steady. Ask the roofer whether the pipe will be checked for movement at the same time the boot is set.

The materials you will see named

Quotes use a few material names for boots. Each one behaves differently over time, and the spec should say which one is going on your roof.

• Neoprene collar on a metal or plastic base. This is the common modern boot. The collar is a synthetic rubber, and it is the part that tends to crack first from sun and age.
• Lead flashing. The collar is molded lead formed around the pipe. It does not crack the way rubber does, but it is soft and can be pushed out of shape if someone steps on it or if the pipe moves.
• Metal base with a sealant collar. Some installers use a sealed collar in place of a rubber boot. Ask what the sealant is and whether the collar can be replaced later without cutting into the shingles around it.
• Preformed or shop-made flashing ring. Some vents, particularly larger ones, use a ring flashing instead of a molded boot. The spec should say whether the ring is preformed or made on the job and how it is sealed to the shingle courses.

None of these names tells you how well the boot was installed. A good material set in the wrong place still leaks. The name tells you what to inspect later and what the crew should be able to show you on the day.

What the spec should say

A spec for pipe boots does not need to be long. It needs to be specific enough that you can check the roof against it after the crew leaves.

1. The boot type and the collar material, named as they will be installed rather than as a general pipe flashing line.
2. The pipe sizes served, listed by diameter, with each vent shown on the roof plan or in the quote so that nothing is counted twice or missed.
3. Whether each boot is new at installation or reused from the old roof. A reused rubber collar is a poor bet on a roof you intend to keep for a long time, and the spec should say plainly which boots, if any, are reused.
4. Where the flange sits relative to the course above it, and whether the upper shingles are lapped over the flange rather than cut to fit around it.
5. Whether a separate sealant is applied, and the product name if it is.
6. The vent cap or termination that sits on top of each pipe, if the quote lists it separately, so that the top of the pipe is not left out of the price.

Old boots at tear-off

When the old roof comes off, every boot should come off with it, and the crew should look at the pipe under each one before the new boot is set. A corroded pipe or a cracked plastic vent under the boot will leak whatever the new collar is made of, so the pipe condition is part of the boot decision and not a separate issue to discover later.

Ask the roofer to photograph each pipe after the old boot is removed and before the new one goes on. Those photos belong in the job file with the rest of the roof photos, next to the shingle install record. If the crew finds a pipe that needs more than a new boot, the written scope should say what the crew found, what it proposes to do about it, and how the price changes if the work is added. That is a separate line from the boot itself, and it should be written down before the crew makes the change.

Questions to ask before you sign

• What boot material is in the quote, by name, for each vent on the roof?
• Are any boots reused from the old roof, and if so, which ones?
• Is each boot set under the upper shingle course, and who checks that it is?
• Will the crew photograph each pipe before the new boot goes on?
• If a vent is cast iron or cracked, does the quote say how the crew will seal the top of it and what that costs?
• Does the spec name the sealant, if one is used, and is it the same product the shingle instructions allow?

Keeping the record

Keep the quote line that names the boots, the install sheet for the shingles, and the photo set together. If a leak appears near a vent later, that file tells you which boot was installed, what the pipe looked like when it was set, which shingle lot went over it, and when the work was done. Keys documents the work, puts a written scope with photos and measurements in your hands, and attends as the contractor while the job runs. Keys installs Atlas and Malarkey shingles only, and the boot line should be read together with the shingle spec, since both go on the same roof and both are part of the same warranty conversation.

If you want a boot specification checked against your own roof before you choose, call the Keys office at (314) 220-2333.