How To Vent A Washing Machine Drain Pipe


Suppose you hear some noise from the washing machine and the floor starts to flood. You turned off the water very quickly. There’s still water in the washing machine and the drain seems to be blocked. You ask yourself, is my washing machine drain ventilated or clogged

As with all plumbing, ventilating the washing machine properly is crucial. Otherwise, it becomes noisy, dull, and even emits harmful fumes.

You don’t need a separate vent for your washing machine. You can have a universal exhaust pipe. This way, all fixtures in your home will share one. You must ensure that all connections are above the flood level edge of the highest device.

This article provides you with a guide on how to vent the drain of your washing machine. Read on to follow the steps.

How Washing Machines Drain

Your washing machine is a very complex system. At the end of the cycle, the pump pushes the water out of the tub and into the washing machine’s drainage hose. The drain hose bends upward to the standpipe. The riser is located near the hot and cold water valves. Assuming all goes well, the water will flow up into the standpipe and out into the sewer.

If for some reason you malfunction during the whole process, the washing machine will not be able to drain and the water may backflow and leak onto your bathroom floor.

Why Should You Vent a Washing Machine Drain Pipe?

Drain Pipe

Prevents the Formation of Vacuum in the Drain

A washing machine drain is necessary because it allows air to enter. This prevents a vacuum from forming in the drain pipe, which can interfere with wastewater removal.

Depending on the building code in your area, you may not need vents. But there needs to be a gap around the drain. This prevents a vacuum from forming in the drain. That way, it doesn’t interfere with the flow of water.

Protects Health and Prevents a Fire Hazard

Once you have installed the trap, venting the washing machine is vital. This is because negative pressure can also draw water out, rendering the P-trap useless. Unless you are prepared to overflow, you must let the water out of the washing machine, and of course, venting the washing machine can prevent it from overflowing

Prevents Overflow

Inadequate ventilation can also cause washing machines to drain slowly and overflow. This will cause it to overflow. A gap around the drain will maintain a vacuum so as not to interfere with the flow of water.

Protect the Health and Prevent Fire Hazards

You must also make sure that you use a trap or p-type trap to seal sewer gases and prevent them from entering your home. Sewer gases contain harmful microorganisms that can be hazardous when inhaled, and some gases can be flammable. Therefore, having a drain tap is a necessary measure to protect your health and prevent fire hazards.

When Should You Vent Your Washing Machine Drain Pipe?

f the drainpipe of the washing machine fits closely with the drainpipe, it needs to exhaust the drainpipe of the washing machine. This will prevent vacuum formation and affect washing machine drainage.

If your washing machine is more than 4 feet from the exhaust pipe, it should also be installed. This is to make sure there is enough space for the washing machine to drain properly.

How Big Should the Washing Machine Drain Pipe Be?

Washing machine drainpipes should be at least 1.5 inches inside diameter for proper drainage. The washer drain hose has an outer diameter of 1 1/4 “OB. Your drain line should be at least 30 inches high to install top load gaskets. The height will prevent water siphoning.

What Is Needed To Vent the Washing Machine Drain?

In most cases, the conditions required for the washing machine drainage system to work properly are as follows:

  • Standpipe horizontal from drain to gasket at an Angle of 1/4 inch per foot with the drain.
  • P- Trap – necessary to ensure that water does not stand still. In addition, create a sealed sewer where gases do not enter your home.
  • Ventilation riser This is a straight pipe (usually vented through the roof) for discharging sewer gases.

When the water flows, by opening the valve to allow air into the line, the cheat valve produces negative pressure. Not all places are legal, so be sure to check local building codes before installing.

How To Vent A Washing Machine Drain Pipe?

Drain Pipe

Here are the steps on how to vent a washing machine drain pipe:

Step1: Choose the vent route

The first step in emptying the drain pipe of the washing machine is to select the exhaust pipe route of the exhaust pipe. Make sure it is in the shortest direction. Choose according to the location of your washing machine.

Washing Machines for Indoor Rooms

If your washing machine is located in an indoor room of your house, you will let the vent pass through the roof. That means it goes through the attic.

When Washer Is Located in an Underground Basement

If your washing machine is in the basement, you have to push the ventilation ducts up. It will pass through the outer walls and edge joists. Make sure the vents are at least 12 inches above the floor.

You don’t need to use more than 25 feet of 4-inch pipe to run the vents from the basement. Just subtract 2.5 feet for 45 degrees and 5 feet for 90 degrees. For example, if a 45-degree bend was to be inserted between two points in the wall, it would pass through the duct about 20 feet.

Washer Close to an Exterior Wall

If your washing machine is near an outer wall, you can just let it out. It’s easier than running underground. The required pipe length would also be shorter. But make sure the vents are at least 12 inches above the ground.

Step2: Take measurements

After locating the vent, take the necessary measurements to complete the job, which helps verify the exact duct length required. Consider bending when measuring dimensions. When performing this operation, pay attention to the placement of accessories. First, measure the distance from the drain pipe to the location of the external vent. You also need to check how many ventilation ducts are required.

Depending on how many turns you’re turning, it helps if you have a few elbow fittings or joints.

The elbow fitting will help to direct the metal pipe to the optimum route. Just get all the materials you need to start the project.

Step3: Buy Necessary Materials

Buy all the materials you need. This will include an outdoor cover and an ample supply of straight piping and fittings. You can choose to buy galvanized steel or aluminum piping. But make sure you don’t mix up the parts.

Step4: Drill a Test Hole

Now, to begin the project, drill a test hole in the edge joist or wall. Using a 1/4 inch drill bit, drill a test hole in the wall or edge joist. Then, position the point externally to ensure that the area is free of obstructions. This is done to ensure that the location is free of obstructions. This will help you check the best place for the cover. If it’s too low or there’s a problem, you can quickly fill in the holes and then try another area.

Step5: Drill the vent hole

Once the ideal location is found, drill the vents and make sure they match the siding. Next, place the top of the ventilation cover on the high point of the lap panel. The cover is then removed from the duct for measurement.

Holes shall be 4 1/4 inches in. Drill holes with a hole saw. Be sure to hold the drill firmly. Periodically pull it back to remove debris and dust. Then continue until a hole is drilled in the edge joist.

Step6: Install the Vent Cap

Next, install the ventilation cover. First, drill holes in the area. Then screw on the vent cap. Check for deep clearance and push the foam support rod through. Seal the area with acrylic caulk.

A ¼ inch masonry bit and hammer drill will be required to drill through stucco or brick finishes. Draw a 4-1/2 inch circle. Then drill tightly spaced holes in the circle. Next, break it with a cold chisel.

After that, the wire mesh used for stucco is cut. Then drill holes in the wooden frame with a 4-1/4 inch hole saw.

For vinyl siding, vinyl surface pads must be installed. It should be on the wainscoting. Trim the edges to match them. Then, screw the mounting block onto the surface. Be sure to drill a slightly larger hole in the siding to allow for movement.

You can also install the lid onto the vinyl siding by removing an area on the vinyl siding. Then, insert the vinyl mounting block onto it. After that, install the siding so that it fits around the cylinder block.

Step7: Connect Elbow Fittings

Make sure elbow joints are installed where needed. One connection shall be placed on the drain outlet and the other on the external vent.

Be careful with accessories, as they strengthen the structure. Make sure the solid end of the connector is connected. Also, make sure the distance between the elbow fittings is accurate.

Step8: Cut the Duct

Before cutting metal pipes, wear a pair of heavy gloves to protect your hands from sharp pipes. Then, according to the measurements made on the structure, the vents are cut.

Tin strips can be used for this purpose. Make sure the cut size fits the elbow fitting. There is only one section of pipe from the gasket to the outside.

Step 9: Align the Seam Edges

After connecting the air duct, align the joint edges. To do this, pull the long ends of the vents together.

When joining the joints, form a circle of metal. Start at one end of the duct.

Step 10: Connect the First Duct

Then, connect one end of the first duct to the elbow. Be sure to connect it to the crimp end. Secure the connection in place using foil tape. Avoid using screws. This is because they cause lint to pile up when they become obstacles.

Do not use duct tape as it quickly loses adhesion and does not seal gaps properly.

Step 11: Connect the Remaining Air Duct Segments

Now connect the other duct segments. As in the first, insert it into the crimp end of the elbow joint. Do this with all of these and secure the ends together with foil tape.

Insert the crimping end of the last bend into the duct cover and tape it down.

Step12: Screw the Vent to the Wall

The next step is to screw the vent into the wall. First, drill guide holes in the wall to allow the screws to pass through. Drywall anchors are pushed into points to support fasteners. Then, place a U-shaped band around the duct.

Then, insert the screw with a screwdriver to secure the duct. Place a hose clamp every 6 to 8 feet of straight pipe to minimize strain on the tape joint.

Step 13: Insert Gasket

Now, insert the gasket. You can open it when you’re ready. Then check the exterior to make sure the ventilation valve is open.


Washing machine vents are essential because they prevent water from flowing out improperly. It also protects against overflow, performance sluggishness, and noise.

Properly installed vents will help p-Trap work properly. That way, you won’t have dangerous sewer gas entering your home.

If your washing machine doesn’t have a vent, it can cause the drain to overflow from the pressure. In addition, it may affect the performance of the trap (p-type trap).

If you have the right tools and the necessary materials, you can install the vents yourself. All you have to do is buy the necessary materials and tools. Then follow the installation guide to install it. If you’re feeling stressed, contact a professional.

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