How to Vent a Kitchen Sink That is Under a Window

Venting a kitchen sink under a window is very important because it helps prevent the pipes from clogging, and enhance fresh air.

Knowing how to vent a kitchen sink that is under a window is vital because pressure from the pipes forces the P-traps to empty. As a result, the sewer gases get to enter into your kitchen or entire house.

Most vents in a home connect to the central vent that extends vertically through the house’s roof. In case a window occurs along the way as you run the vent, the best approach is to run the vent horizontally along the area with the window. But the horizontal vent should run in an upward slope for optimal results.

Unfortunately, many homeowners don’t know how to install a vent pipe for the kitchen sink that is under a window. With this following step by step guide, you will find it easy to vent your prolific kitchen sink.

How to Install a Vent Pipe for the Kitchen under Window:

The kitchen is one of the busiest rooms in a home due to its nature of use. Different foods and drinks used and made in it attribute to the many smells from the kitchen. Proper ventilation in your kitchen is therefore essential.

If the sink doesn’t get ventilated adequately, it becomes difficult to drain the water. As a result, the water gets to lock inside the drain pipes, and the waste to get disposed don’t get removed efficiently from these pipes.

If you follow the following guidelines in venting a kitchen sink for a window, you get assured of an easy process. But first, you will need to have the following items.

Required Items:

  • Hack saw
  • Drill
  • PVC sanitary tee of 2 x 2 and 1 x ½ – inch
  • Chalk line
  • Tape measure
  • Three long-sweep elbows of 1 x ½ – inch
  • PVC cement
  • Hole saw of 1 x 5/8 – inch.

Step 1: Installing a Sanitary Tee

The first step is to put a sanitary tee inside the drain line of the sink. That means that the installation will happen inside your kitchen’s wall cavity since it’s where we get the drain line of the sink. If the waste line is 2 – inch wide, use the 2 by 2 – inch PVC sanitary tee.

Then take a tape measure and measure 3 ½ ft. from the P-trap’s bottom. Then install the sanitary tee at this point because it shouldn’t get placed beyond this length from the P-trap.

Making sure that the 1 ½ port faces upward, use the PVC cement to stick the tee to the sink pipe. Ensure you glue up to the drain’s continuation and the tee’s other side.

Step 2: Insert a PVC Pipe

Take a tape measure and measure the PVC pipe up to 2 – inches long. Then use a hacksaw to cut out the measured pipe.

Using the PVC cement, glue it to the sanitary tee’s 1 ½ – inch port. Then take the sweep elbow and place it to the pipe. Ensure that it faces directly to the wall then also glue it to the tube.

Step 3: Draw a Line beyond the Window

Check out the kitchen window above the sink and locate a point beyond the window where the pipe will run vertically.

Then snap the chalk line to that point. The upward slope of the line should not be less than ¼ – inch per foot.

For instance, if the position you’ve located is 2 fts apart with the elbow, the line should rise not less than ½ – inch.

Step 4: Hole Drilling

Take a drill and make 1 5/8 – inches holes into every stud found between the point that the vent will rise and the elbow. Ensure that each hole is on the line. A hole saw will also be ideal to use in the process. Read this guide to cut a hole in a stainless steel sink.

Step 5: Cut 1 ½ – inch Length Pipe

Using a hack saw, cut a pipe of 1 ½ – inch in length to reach the mounting point of the vent from the elbow.

Then insert it carefully through the holes drilled in step – 4 above. When you finish, take the PVC cement and glue the pipe to the elbow.

Then take another elbow and stick it to the pipe’s other side. Ensure that its outlet faces upward.

Step 6: Drill a Hole

It is the last step for installing a vent pipe for the sink. On the wall’s top plate, use a drill to make a 1 5/8 – inch hole.

Then through that hole, extend the vent to reach the attic. Connect it to the primary vent stack by making it run horizontally to the stack.

Using a stack fitting reducing sanitary tee, tie the new vent with the central vent stack. Voila! You have now vented a kitchen sink.

But as you implement the above steps, the following points are essential to keep in mind.

  • When routing your new vent via the attic, maintain a slope of not less than ¼ – inch for every foot.
  • Consider the material used in making the already installed vents. If ABS pipes get used in making the central vent or other existing vents, use the same ABS pipes to make your kitchen sink vent. Then use ABS glue to connect them and not the PVC glue.

Despite grasping knowledge for venting a kitchen sink under a window, you may have many questions that need answers. To help solve some of those questions, here is a list and answers of the frequently asked questions.


a) Does Kitchen Sink Need to be Vented?

Absolutely! All sinks require a vent. Otherwise, they may not function properly. If a kitchen sink doesn’t get vented, the pressure from the flowing water doesn’t equalize.

As a result, the air in the drainpipe doesn’t escape, and the waste cannot get drained efficiently. It also causes a foul smell into your kitchen.


b) Can You Vent a Sink Out a Wall?

The best way to vent a sink is through the roof or attic. This way, the gases can rise over and away from the kitchen.

But if it’s not possible to install the kitchen sink vent on the roof or attic, you may vent the sink out a wall.

But ensure the vent’s exit is at least 6 – inches above your roofline. Regarding this, the gas won’t be in a position to seep back in via openings in your house. For example, through the windows.

c) Does Every Fixture Need a Vent?

All plumbing fixtures like copper sinks should have a vent. The plumbing system buildup harmful gases and grimes, and we must get rid of them.

The only best way to expel such gases is through vents. Also, the gases should get disposed outside and away from the building.

That’s why there’s usually a primary vent that connects other vents from various fixtures in a house.

The central vent gets installed to raise above the roof and far from the home so that it can expel all the gases from the vents away and far into the air.

The vents also helps in bringing oxygen into the entire plumbing system. As a result, the waste products gets broken down more efficiently and quickly.


The venting process may be hectic, but the method explained above makes it easier. If time is on your hands and you have the tools described above, you can also vent a stainless steel farmhouse sink using the above step by step guide.

More so, when the sink vent gets connected to the main vent, the gases don’t get into the building. Instead, they get expelled over the roof and away into the air. As a result, the bad and harmful smell doesn’t get to reach you, ensuring you stay safe and healthy.

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