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How to Make A Plumbing Loop Vent?

Do you have recurring unpleasant sewer gas leakages in your home? Its time you installed a plumbing loop vent to solve the problem once and for all.

The plumbing loop vent ensures a complete fresh air circulation through your sinks and toilets giving you a perfect circulation in your home.

Making a plumbing loop vent is not an easy task as many people may assume. It requires thorough understanding of the plumbing setup and the requisite skills to make the vent.

However, this should not scare you from doing the project by yourself. You just need to draw a Vent diagram for our set up, then take the pipe measurements. Measure the pipe lengths and connect the pipe from the P-trap to the stack. Carefully follow the plumbing codes and stack the vent using elbows and Tees making perfect loops.

We dived into this topic and came up with this detailed guide to help you through this essential project. Keep reading and make your home a better place to breathe in.


What is a Plumbing Loop Vent?

This is a ventilation system that emits waste gases to the environment at a high point above your house giving you a safe and comfortable home to live in. the design of loop vents allows the waste to flow to the wet vent and drain pipe while the clean fresh air circulates through the dry vent.

Why Do You Need A Loop Vent?

A loop vent ensures that your house has fresh air at all times as it allows maximum ventilation for all the fixtures in your house through the drain pipe.

The main task of a loop vent is to prevent any backflow of sewer gases into the house which makes your home unhabitable and it can also be a health hazard. It also maintains the right air pressure in your plumbing system which ensures that your drainage system works more efficiently and safely.

Without a loop vent in your system, you will have issues of pope blockages leading to nasty odors and unprecedented health hazards.

Every sink in the house has a trap that keeps water to prevent gases from flowing into the house and this enhances the loop vent system. The toilet has a loop vent trap that is inside the sink while the kitchen island sink has a trap underneath the sink.

How To Make A Plumbing Loop Vent?

There is no better way to cleanse the air in your house than installing a loop vent. This can be a challenge for a first time home owner or first time installer. This guide will show you how to go through every step and install an airtight loop vent.

What Do You Need To Make a Plumbing Loop Vent?

To make the project seamlessly successful you will need to get the following items first.

  1. PVC plumbing vent pipe
  2. Pipe Cement
  3. Hacksaw
  4. Marker Pen
  5. Elbows – 45 and 90 degrees Y fitting
  6. Tape measure
  7. Sanitary and vent tee
  8. Protective gloves
  9. Coupling and Adapters


  • Draw the Loop Vent Diagram

The first thing you need to do is draw a vent diagram of your project to scale. Then label all the parts in the diagram. It is also very important to get all the measurements correctly as per the local plumbing code in your area. Clearly mark the type of elbow and tees you need to fix on the diagram.

Once you get the diagram ready, you can now get all the materials as listed on the diagram.

  • Measure and Cut the Pipe

The first pipe to cut will be the one running from the P-trap to the stack vent. To get the accurate length, add all the lengths from the diagram and convert them to a suitable unit like millimeters or centimeters.

Using your marker pen, clearly mark all the cut points.  You should always consider the connectors you will be using and allow some space for them. Using the hack saw cut the pipe on the marked points, you can use a sandpaper to remove the burrs left after cutting.

  • Attach The Loop Vent To The P-Trap

A sanitary tee should be used to connect the loop vent with the P-trap. Using the sanitary tee gives you some allowance to add extra joinery. Ensure the slanting side of the sanitary tee faces down towards the drain pipe.  Once you are comfortable with the connection, glue the vent with the pipe cement to make a leak proof connection.


  • Create The Loop

After successfully connecting the sanitary tee to the P-trap, all the way down to the drain pipe, you can now construct the loop depending on the measurements. Then fix a pipe vertically 6 inches above the P-trap as this is the standard height.

Get the 45 degree elbow and connect it to the vertical part of the extension pipe. To completely curve the loop, join a 90 degree elbow on top of the 45 degree elbow. Join another 45 degree elbow going downwards to make the top loop. Finally use the pipe cement to glue all the joint to achieve water tight connections.

At the end the loops top end will be touching the counter tops bottom side if the correct code lengths were used.

  • Tie the Loop Vent to the Stack Vent

Using the hacksaw, cut the PVC pipe and fix it to the lower end of the 45 degrees elbow. Connect the loop vent to the stack vent by putting a vent tee on the ground level. The ground should have an upward slope in that section to allow for perfect air circulation and smooth waste drain.

The pipe and the stack vent will be connected using s Y-fitting or a 90 degrees elbow.

  • Connect the Loop Vent to the Drain Pipe

Connect the pipe with a 45 degrees elbow to the remaining opening of the vent tee to give the pipe a slanting position. To finish the vent pipes loop, use a 45 degree wye at the drain pipe joinery point.

This is a vital part as it drains away any water that may try to find its way into the dry vent.

Finally the plumbing loop vent is fully installed and you can now chill and enjoy you fresh and foul free house.


The process describe above can be used on any appliance in the house that require venting. However, you may need to engage an expert to fix a vent for a toilet or a bathroom.


Where Can You Install a Loop Vent?

Most local codes only specify the use of loop venting in kitchen islands and lavatories and not for toilets and other fixture drains like standalone showers and claw foot bathtubs.

You cannot install a loop vent on a vessel sink as it is located above the counter and the loop must rise as high as the drain opening.  You can install many loop vents in a common vent stack.


For kitchen with multiple sinks or an island in the kitchen, you will install a vent loop for every P-trap. The vent loops can be joint to a common vent that joins the main vent stack. To make this a success ensure that the tie-in point is at least 6 inches above the flood level of the highest fixture in the configuration.

How High Should You Install The Loop Vent?

The Loop vent code recommends that the vent should never exceed 6 feet of lift. For extra tall buildings the vent should not exceed 8 feet.

If the vent is near any opening of the house, it should be installed at least 1000mm over the eaves. This keeps the waste gases far enough that they cannot be blown into the house by the wind.

When the island loop gets above the roof, give an allowance of 1 meter above the roof. Cover the loop end with a perforated lid to allow air in.

Can a Plumbing Vent Have an Elbow?

The answer is YES! You will need 45 degree and 90 degree elbows to connect the loop. This makes it easy to make bends and loop the loops.


Installing looping vents in your home not only improves the quality of your life but it also gives your plumbing system a life line.

If you feel the project is very complicated, do not hesitate to involve your local plumber to achieve best results.