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How to Make a Plumbing Loop Vent?

Plumbing loop vents allow for ventilation around your home by allowing complete fresh air circulation in your sinks and toilet.

However, making a plumbing loop vent can be challenging. You need to have the necessary knowledge and skills to make the vent.

How to make a plumbing loop vent? You can make a plumbing loop vent on your own. Draw a well-labeled loop vent diagram and take the pipe length measurements. Connect the pipe from the P-trap down to the drain and stack vent using elbows and tee while making loops guided by the plumbing codes.

Keep reading the article to learn more details on making a loop vent while trying to understand the purpose of the vent in your homestead.

How to Make A Plumbing Loop Vent

What is the Purpose of a Loop Vent?

Having fresh air in the house makes your living comfortable. However, the waste from your bathroom and toilet can make your house smell like a dumpsite. A loop vent is designed to ensure ventilation and circulation of fresh air in your house.

A loop vent is connected to the drain pipe in your house to provide a continuous flow of fresh air—the plumbing loop vent loops around the fixture to allow maximum ventilation.

The loop end is high above the housing structure to emit waste gasses to the environment. The loop vent is designed to allow the flow of waste to the wet vent and drain pipe and allow fresh air circulation through the dry vent.

The sink contains a trap that keeps the water to prevent gasses from returning to the house, which enhances the loop vent system. The Loop vent for toilet has its trap located inside the sink, while the trap for a kitchen island sink is located beneath the sink.

How To Make A Plumbing Loop Vent?

It would help if you had a plumbing loop vent at your house. Vent plumbing in a house is challenging for first-time installers. However, we shall guide you through how to make a plumbing loop vent easily.

Tools and equipment you need to make a plumbing loop vent

Get the following items to help make your work easy.

  • PVC plumbing vent pipe
  • Elbows – 45°, 90° Y fitting
  • Sanitary and vent tee
  • Pipe cement
  • Tape measure
  • Hacksaw

Draw the Loop Vent Diagram

Draw the loop vent diagram to a scale. In the diagram, ensure you label the various parts. In the labeling, ensure you include the correct measurements according to the standard plumbing code. Also, indicate the type of elbow and tee to fix.

With the diagram ready, you can now seek to purchase the items listed.

loop vent diagram image

Measure and Cut the Pipe

Add the lengths from your diagram and convert them to millimeters or any other suitable unit. The length should be from the P-trap to the stack vent.

Use the tape measure to take the distance from the top of the vent to the floor (app, 6” above the p-trap).

Using a marker pen, make marks at cutting points. Take into consideration the space for the connectors. Cut the pipe using a hacksaw and remove the burrs with sandpaper.

Attach the Loop Vent to the P-Trap

Connect the plumbing loop vent to the P-trap with a sanitary tee. The sanitary tee will allow for extra joinery. Connect the sanitary tee with the slanting side facing down to the drain pipe. Glue the vent using plastic pipe cement for leak-proof connections.

Create the Loop

Having connected the sanitary tee to the P-trap and down to the drain pipe, construct the loop considering the measurements. Fix a piece of the pipe vertically to achieve the standard height. The standard height is 6” above the P-trap.

Connect a 45° elbow to the vertical section of the extension pipe. To curve the loop, connect a 90° elbow to the top end of the 45° elbow. Fix another 45° elbow going downwards to create the top loop. Glue the joints for a water-tight connection.

The loop’s top end should touch the countertop’s bottom side with the correct prescribed code lengths.

Tie the Loop Vent to the Stack Vent

Cut a section of the PVC pipe and fix it at the lower end of the 45° elbow. At the ground level, put a vent tee to connect the loop to the stack vent. The ground in that section should be sloped upward to allow air and waste flow.

Use a Y-fitting or 90° elbow to connect a section of the pipe to the stack vent.

Connect the Loop Vent to the Drain Pipe

From the remaining opening of the vent tee, connect a section of the pipe using a 45° elbow to give the slanting position for the pipe. At the drain pipe joinery point, use a 45° wye to finish the vent pipes loop connection.

This part is essential in draining away any water that may find its way into the dry vent.

The plumbing loop vent is successfully installed, and you can now enjoy your time in the house with no foul odors.


The above-discussed process is for installing a plumbing loop vent for sinks. However, the good news is that the process is similar to homestead appliances that require venting.

Making a plumbing loop vent for the toilet and bathroom will use a similar process but may require a professional plumber to fix it.

How High Does a Loop Vent Need to Be?

According to the loop vent plumbing code, the vent should not exceed six feet of lift. For maximum heights, the vent should not exceed 8 feet tall.

For loop vents that are near any opening to the house, they should be at least 1000mm above the eaves. This will ensure the wind does not blow the waste gasses back to the house.

Once the island loop vent protrudes above the roofing, give an allowance of 1m above the rooftop. Ensure the loop end is covered with a perforated lid to only allow air in.

Can a Plumbing Vent Have an Elbow?

Yes. A plumbing vent needs to have elbows. The loops are connected with an elbow. Most times, you will require the 45-degree elbow to make loop junctions at a 45-degree angle. For right-angled joints, use the 90 degrees elbow.

In addition to the elbows, you will need to install the sanitary tee, vent tee, and the 45-degree wye to complete connections for more than two pipes. These connectors are essential in ensuring a complete loop with zero leakages. Purchase high-quality connectors and elbows to avoid the headache of replacement.

At the baseline where the loop connects to the drain pipe, use the combining wye with a 1/8” bend to create momentum for the flowing liquids.


Make your living conditions favorable by installing efficient loop vents in your kitchen island and the washrooms. For a long-lasting solution, purchase pipes and elbows of high quality to avoid frequent replacements.

Follow the above guidelines to know how to make a plumbing loop vent on your own. While making the loop, be keen to have the correct measurements and appliances for a smooth fix. Install the loop vent following the given inclination angles for an efficient outcome.

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