Improperly Installed Pipe Causing Moisture Problems in a One Year Old Roof

Sometimes the biggest attic problems start with small installation mistakes. In a recent video Brandon filmed inside an attic, we found a situation where an improperly installed pipe is already creating moisture issues even though the roof is only about one year old.

This home recently had its roof replaced, but during the inspection Brandon noticed something that should never happen on a properly installed roofing system. A plumbing vent pipe, commonly called a stink pipe, was not extended through the roof the way it should have been.

Instead, the pipe terminates inside the attic and points into a box vent, also known as a can vent. While this might seem like a small detail, it can lead to serious problems over time.

This short video is now posted to our TikTok and YouTube Shorts so homeowners can see exactly how an improperly installed pipe like this can affect an attic.

What a Plumbing Vent Pipe Is Supposed to Do

A plumbing vent pipe plays an important role in every home. It is connected to the plumbing system and allows sewer gases such as methane to escape safely outside.

Just as importantly, the pipe allows air into the plumbing system so toilets can flush and drains can work properly. Without proper venting, plumbing fixtures can struggle to drain and may create gurgling sounds.

Because these pipes carry sewer gases and humid air from the plumbing system, they must always terminate outside the home. The proper installation requires the pipe to extend through the roof deck and be sealed with a pipe boot that is integrated into the roofing system.

What Happens When a Pipe Is Installed Incorrectly

In this attic, the plumbing vent pipe was never extended through the roof. Instead, it stops short and discharges into a box vent.

This is a clear example of an improperly installed pipe. Even though the roof vent eventually leads outside, it is not designed to handle a plumbing vent.

When the pipe releases air inside the attic, several things happen.

First, sewer gases are released into the attic space. While they may eventually exit through roof ventilation, they are not being directed outside properly.

Second, warm humid air from the plumbing system enters the attic environment. That moisture can quickly begin affecting the roof structure.

How Moisture Starts Building Up

During colder months in Michigan, attic surfaces such as roof sheathing and rafters can become very cold. When warm moist air from the plumbing vent enters the attic, it can hit these cold surfaces and create condensation.

Over time, this moisture can cause several issues inside the attic including:

• Damp or compressed insulation

• Mold growth on wood surfaces

• Dark staining on roof sheathing

• Rusting fasteners and nails

• Gradual wood deterioration

Even though the roof on this home is only about a year old, early signs of moisture buildup are already visible. This shows how quickly an improperly installed pipe can start causing problems.

Why This Happens During Roofing Work

Mistakes like this often happen when details are overlooked during a roofing project. Installing a plumbing vent correctly requires cutting a penetration through the roof deck and installing proper flashing along with a pipe boot.

Some installers try to avoid that step by leaving the pipe inside the attic and directing it toward an existing roof vent. It may seem like a quick solution, but it does not work properly and it does not follow correct installation practices.

Roof vents are designed to move general attic air slowly. They are not built to handle concentrated sewer gases and moisture coming from plumbing systems.

The Correct Way to Fix an Improperly Installed Pipe

The solution for an improperly installed pipe like this is straightforward. The plumbing vent needs to be extended through the roof deck so it terminates outside the home.

A proper pipe boot should be installed and integrated into the roofing system to ensure the roof remains watertight. Once installed correctly, the vent pipe will safely release gases and moisture outside where they belong.

This keeps the attic environment dry and prevents long term moisture problems.

Why Attic Inspections Are Important

Many homeowners never look inside their attic, which means issues like an improperly installed pipe can go unnoticed for years. By the time damage becomes visible inside the home, the attic may already have mold or moisture related problems.

That is why attic inspections are an important part of roofing work. A thorough roofing contractor will always look at the structure beneath the roof to identify potential issues early.

Catching a problem like this early can prevent expensive repairs and protect the life of the roof.

Watch the Video

Brandon explains this situation in the short video filmed inside the attic, where you can clearly see the improperly installed pipe terminating inside the box vent.

You can watch the video here:

YouTube Here

These short educational videos are meant to help homeowners understand what happens behind the scenes in roofing systems. Small installation details can make a big difference in how well a roof performs over time. To learn more please check out our Blog here for our recent posts.