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How To Seal A Vent Pipe On A Metal Roof | Helpful Guide

How To Seal A Vent Pipe On A Metal Roof | Helpful Guide

A Vent Pipe On A Metal Roof is a great investment for your home. Not only does it protect against the elements, but also provides an aesthetic appeal to your property. With all of these benefits, there are some aspects that need to be taken into consideration as well.

One such aspect is ventilation and air flow inside your house or office building. If you have a vent pipe on top of your metal roof that needs to be sealed, then this blog post will help you understand how to do so!

Steps in Sealing Your Vent Pipe

A metal roof that can be sealed by a vent pipe will require enough work. The sealant should be applied in a step-by-step guideline for it to work.

Preparation and Tools

It’s better to gather all the tools you need before starting a project.

To seal the vent pipe, use a putty knife, silicon caulking, measuring tape and roofing membrane, hammer, rubber gasket and nails.

Step 1: Nails are used to tie flashing in place.

Step 2: In order to remove flashing from shingles, be cautious when removing the material.

Step 3: Use a utility knife to cut the roofing membrane and wrap it around the pipe so that it is waterproof. To seal the roofing membrane, trim off excess that is overlapping.

Step 4: Apply silicone caulk to the roof vent pipes. Put the roofing membrane around the pipe, then install. Fill in the gap between pipes with silicone caulking.

Step 5: The pipe needs to be fixed with the rubber gasket. You might need to make the hole bigger for pipes that are too big. In the last step, silicone caulking is used to seal the bottom of a gasket with cracks.

Step 6: The flashing should be placed on top of the pipe. In order to protect a roof from leaking, it is necessary to raise the shingles and place flashing below them.

A line of silicone caulking should be about an inch away from the edge of shingles. Put nails in the roof to secure it.

Why Seal A Vent Pipe On A Metal Roof?

The vent pipe on a metal roof should be sealed to prevent water leakage.

Metal roofs are very popular because they are durable, long lasting and can last for 50 years or longer. If you live in an area that has cold winters (with snow) and hot summers (without rain), it is a good idea to have a vent pipe on your roof.

A vent pipe is put in place so the water inside the metal roof can evaporate, thus preventing rust from occurring on the metal roof itself.

In some cases, with heavy snow loads and lack of any wind, the vent pipe may clog up with snow.

If this happens you could have a major water leakage from the vent pipe, which can damage ceilings and walls inside your home.

Therefore, you have to make sure that you seal your vent pipe in order to avoid:

1. Water leakage from the vent pipe

2. Rust forming on your metal roof from the lack of evaporation

3. Snow clogging up your vent pipe during winter months

Three Types of Vent Pipes

If you have a metal roof, there are generally three different types of vent pipes used for the different areas on your roof.

  • The first type of pipe that we will discuss is the visible pipe that sticks up from the surface of your roof.
    • You can see it coming out of your shingles and some people refer to this as an exhaust stack.
    • This is commonly used for bathroom fans.
  • The next type of vent pipe that we will discuss is the roof penetration vent. This type of vent penetrates through your roof, but it isn’t visible from the ground.
    • A good example of this is a clothes dryer exhaust vent or an attic fan vent. This information applies to both types of vents.
  • The third type of vent pipe is the one that we will be discussing in this article.
    • This type of vent is called a “thermal stack” or sometimes simply called an “exhaust stack.”
    • It does not penetrate through your roof, but it still must pass all the way through your attic to get from the equipment on the roof to the outdoors.
    • This is the type of vent that you would see for equipment or air handlers located inside your home most commonly seen coming out of an upper floor bathroom ceiling.

Safety Measures When Sealing A Vent Pipe On A Metal Roof

As for safety measures, the first thing is to make sure you are not standing on the roof when applying basic sealant around the vent pipe. If you accidentally slip, falling off the roof might be dangerous.

Any below areas surrounding the vent where water can run should also be cleared so that they will not be flooded if any leaks develop after application of sealant.

Thirdly, make sure you are not standing in the shade when sealing roof vents because if the sealant dries up before it is spread around the pipe, any excess that leaks out will be difficult to clean.

Lastly, remove any debris or leaves that may have collected under the vent pipe to ensure proper application of sealant onto the metal roofing.


In conclusion, make sure you seal a vent pipe on a metal roof with the right materials and techniques to avoid any water leakage from developing.

This is very important because it will prevent rust from forming on your metal roof as well as damage inside your home that could cost thousands of dollars in repairs.

Now that we have gone through all of that, you can go ahead and apply all of this knowledge to your own vent pipe.

Remember, if you are not sure about how to properly seal a metal roofing vent pipe, call in professional help.

How To Seal A Vent Pipe On A Metal Roof | Helpful Guide