How To Vent A Kitchen Sink Under A Window

Most modern homeowners prefer venting a kitchen sink under a window as it helps to enhance fresh air in the kitchen and prevent the pipes from clogging. Proper ventilation is highly necessary for the kitchen because the kitchen is one of the busiest places in the house, where food, drinks, and consumables are stored. And proper ventilation helps to dispose of water effectively in the pipes and prevent sewage gases from entering the home. As such it is necessary for you to know how to vent a kitchen sink under a window.

In most modern homes, sink vents are connected to the central vent that runs vertically through the house’s roof. If there is a window located along the way you vent, the best approach is to extend the vent horizontally along the area with the window. But if it is a horizontal vent should, it should run in an upward slope to achieve a successful result.

For this to be possible, you must know how to install a vent pipe for the kitchen sink that is under a window. On this light, I will be showing you how to install a vent pipe for the kitchen under the window.

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

To install a vent pipe for the kitchen under window, there are some items you must get and they are:

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

The steps include:

Step 1: Fixing a Sanitary Tee

The first step to take is to install a sanitary tee inside the sink’s drain line. This explains that you will have to do the installation inside the kitchen’s wall cavity because that is where the drain line of the sink is located. If the waste line is 2 inches wide, it is expected you use the 2 by 2 – inch PVC sanitary tee.

Next, using a tape measure, measure 3 ½ ft. from the P-trap’s bottom. Then put in the sanitary tee on the marked point (the sanitary tee shouldn’t be placed beyond this calculated length from the P-trap).

Next is to make sure the 1 ½ port faces upward. To achieve this, use PVC cement to glue the tee to the sink pipe. Ensure the drain is well glued to the tee’s other side.

Step 2: Install a PVC Pipe

First, take a tape measure and measure the PVC pipe, and it should be up to 2 – inches long. When you have measured it, mark the spot, and use a hacksaw to cut out the measured area of the pipe.

Use the PVC cement, to glue the pipe to the sanitary tee’s 1 ½ – inch port. Then insert the sweep elbow into the pipe. Do ensure the pipe is directly facing the wall, after which you glue it to the tube.

Step 3: Locate a Line above the Window

Locate any line above the kitchen window above the sink and marked out a point above the window where the pipe will run vertically.

Next, draw a chalk line to that point. While drawing, the upward slope of the line should be below ¼ – inch per foot.

For example, if the position you located and marked is 2 ft apart from the elbow, you shouldn’t rise the line not less than ½ – inch.

Step 4: Take a Hole Drilling

Drill a hole, and ensure that every hole into the very stud is 1 5/8 – inches deep. And each hole must be on the line. To create a flawless hole, I recommend you use the hole saw and it also helps simplify the process.

Step 5: Cut 1 ½ – inch Length Pipe

Cut a pipe of 1 ½ – inches in length using a hacksaw to reach the mounting point of the vent from the elbow.

Then, carefully insert the cut pipe into the holes drilled in the previous step. Upon completion, take the PVC cement and instantly glue the pipe to the elbow.

Next, take another elbow and glue it to the pipe’s other side. Do remember that the outlet faces should be upward.

Step 6: Drill a Hole

Drilling a hole is the last step to make venting a kitchen sink under a window successful. On the wall’s top plate, use a drill to make a 1 5/8 – inch hole.

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

Using a stack fitting reducing sanitary tee, knot the new vent with the central vent stack. That’s all and you are done.

You can easily carry out the DIY approach to make this happen. Despite acquiring the knowledge for venting a kitchen sink under a window, you may be perplexed in some of the processes which may demand professional hand or repair. So in that case, you can opt-in for a plumber.

Frequently Asked Questions (FAQs)

Why are kitchen Sinks Always By Windows?

Traditionally kitchen sink has always been by the windows and this is because the window is, obviously, stuck on the outside wall, and serves as a great exit point. Apart from that, it serves as the best option regarding where kitchen sinks can be situated in the kitchen.

What Is The Appropriate Window Size Above The Kitchen Sink

To get this, you must first calculate the height of your cabinets. Typically the height of the cabinet is  34 1/2 inches — and the thickness of countertops is usually 1 1/2 inches. From these calculations, the widow size height should be 37 inches following an average standard of a modern home.

Does Kitchen Sink Need to be Vented?

Yes of course. To ensure proper functioning, adequate ventilation and make the kitchen appear less stuffy; you need to vent the kitchen sink. If you don’t get a kitchen sink well vented, the pressure from the flowing water won’t be stabilized which can obstruct the flow of the air in the drainpipe which prevents the waste from the pipe to get drained efficiently. This will cause a foul smell in your kitchen.

Is it Necessary to Vent all Fixtures?

Plumbing fixtures like copper sinks must be vented. This is highly necessary because in the plumbing process, there is a buildup of harmful gases and grimes, in the fixtures and we must get rid of them, and the best way to ensure this happens is through venting. This is the reason why there is always a primary vent connecting other vents from the various fixtures in the house. Usually, this primary vent is also called the central vent and it is usually raised above the roof and far from the home so that it can expel all the gases from the vents away without any escaping back to the house.

Apart from aiding the removal of harmful gases and wastes, the vent also functions to aid the easy flow of oxygen into the entire plumbing system.

Should A Kitchen Sink Be Under The Window?

Although not mandatory, having a kitchen sink under the windows allows for easy inflow of fresh air in the kitchen which boosts kitchen ventilation and helps in getting rid of the unwanted smells. Also, this also serves as a great place to help out with some mild kitchen disasters. For instance, when you burn your pot or frying plates, you can easily place them, in the sink and open the window, letting the smoke run out through the window.

Can You Vent a Sink Out a Wall?

Yes, you can but it is not a very wise decision to take. The best and most appropriate way to vent a sink is through the roof or attic. In this way, the gases can easily rise over and out of the kitchen.

However if your kitchen is built in such a way that it is not possible to install the kitchen sink vent on the roof or attic, you can try out venting the sink out a wall.

While carrying out that latter, you have to ensure that the vent’s exit is at least 6 – inches above your roofline. This is important because, it won’t provide the opportunity for the gas to seep back in via openings in your house, which can cause a big mess in the kitchen.

Are kitchen Sinks Supposed To Be Vented?

Venting is very important to the sink to reduce the pressure put on the drain pipe and the equalization of air in the drainpipe needs to equalize.


The venting process sometimes can be hectic. If you follow the above steps, you are sure to make things easier for yourself. Using this step you can also vent the stainless steel farmhouse sink. Remember that venting is highly necessary as such it should be done for all the fixtures at home.

You can also check out this post, “How To Hide Kitchen Vent Pipe.”


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