Check Out How To Vent A Washing Machine Drain Pipe

Like all plumbing fixtures, venting your washing machine correctly is crucial. Otherwise, it can become noisy, sluggish, and even emit harmful fumes.

You don’t need to have a separate vent for your washing machine. You can have a general vent stack. That way, all the fixtures in your home will share a common one. You have to make sure that all the connections are above the flood-level rim of the highest equipment.

This article gives you a guideline on how to vent a washing machine drain pipe. Read on to follow the steps.

How To Vent A Washing Machine Drain Pipe

To vent your washing machine drain pipe, you need the following tools and materials:

  • Tape measure
  • Drill bit set
  • Tin snips
  • 4-in-1 screwdriver
  • Caulk gun
  • Exterior caulk
  • Corded drill
  • 4-inch duct
  • Metal foil tape
  • 4-inch elbow joints
  • U-shaped pipe straps
  • Vent cap

Step#1: Choose the vent route

The first thing to do is choose the vent route. Ensure it’s in the shortest direction possible. Select it based on the location of your washing machine.

If your washing machine is in an underground basement, you have to run the vent duct up. It’ll pass through the exterior wall and the rim joist. Ensure the vent is at least 12 inches above the ground outside.

You don’t need more than 25 feet of 4-inch duct to run the vent from the underground basement. For every 45 degrees turn, subtract two and a half feet. And remove 5 feet for every 90-degree turn.

For instance, if you insert 45-degree elbow joints at two points of the wall, you’ll run about 20 feet through the duct.

If the washing machine is close to an exterior wall, you can run it straight out. It’s simpler than an underground location. The distance required for the duct is also shorter. But ensure the vent is at least 12 inches above the ground outside.

However, if the washer is in an interior room in your house, you’ll run the vent through the roof. That means it’ll pass through the attic.

It’s advisable not to install it through your roof unless it’s a last resort. That’s because the vent caps can be a nest for birds and squirrels over time.

Step#2: Take measurements

When you’re sure of the vent location, take the necessary measurements to get the job done. It’ll help you determine the exact duct length you need. Allow for bends when taking sizes, and note the placement of the fittings as you do so.

First, measure the distance from the drainpipe to the vent hole location outside. You also need to check how many vent ducts you’ll need.

Depending on how many turns you’ll make, it’ll help if you have several elbow fittings or joints.

The elbow fittings will help direct the metal duct to the best route. Just get every material you need ready to start the project.

Step#3: Buy necessary materials

After that, buy the necessary materials. Purchase enough straight duct and fittings. Remember to add an outdoor cap to the list.

You can buy galvanized steel or aluminum duct. But never mix the parts.

Step#4: Drill a test hole

Now to start the project, drill a test hole through the rim joist or wall. You can do that with a ¼ inch bit. Then locate the spot outside.

The point of this is to ensure there’s no obstruction at the location. It’ll help you check the best position for the cap. If it’s too low or has issues, you can quickly fill the hole and try another area.

Step#5: Drill the vent hole

When you find the best position, drill the hole. Ensure the hole fits the siding. You can test it to be sure. Next, let the top of the vent cap rest on the high point of the lap siding. Then remove the vent cap from the duct so you can take measurements.

The hole should be a 4-1/4 inch hole. Use a hole-saw to bore it. Ensure you hold the drill firmly. Pull it back regularly to clear the dust and debris.

Continue till you bore a hole through the rim joist.

Step#6: Install the vent cap

Next, install the vent cap. First, drill screw holes in the area. Then screw the vent cap to it. Check for deep gaps and push foam backer rods through them. Use an acrylic caulk to seal the area.

For drilling a hole through a stucco or brick veneer, you’ll need a ¼ inch masonry bit and hammer drill. Draw a 4-1/2 inch circle. Then drill closely-spaced holes in the circle. Next, break it with a cold chisel.

After that, cut the wire mesh for stucco. And then use a 4-1/4 inch hole saw to drill through the wood framing.

For vinyl siding, you have to install a vinyl surface block. That should fit over the siding. Trim the edges to match them. Then, screw the mounting block to the surface. Ensure that you drill slightly oversized holes through the siding to allow movement.

You can also install the cap on vinyl siding by removing an area from it. Then, insert a vinyl mounting block against it. After that, install the siding to fit around the block.

Step#7: Connect elbow fittings

Now, connect the elbow fittings. Ensure you put them where you need them. Place one on the drainpipe output and another on the outer vent.

Make sure you connect the solid end of the fitting. And ensure that the distance between the two elbow joints is accurate.

Be careful while working on the joints because they strengthen the structure.

Step#8: Cut the duct

Now you have to cut the metal duct. To do this, put on heavy gloves to protect your hands because they’re sharp. Then cut the vents according to your measurements for the structure. You can use tin snips for this.

Ensure the sizes you cut can fit the elbow joints. There should be only one duct section leading from the washing machine to the outside.

Step#9: Align the seam edges

When you’ve connected the ducts, you need to align the seam edges. To do this, pull the long ends of the vents as you force them together.

Form a circle with the metal as you connect the seams. Start at one end of the duct.

Step#10: Connect the first duct

After that, connect one end of the first duct to the elbow joint. Ensure you join it to the crimped end. Use metal foil tape to hold the connection in place. And avoid using screws. That’s because they cause lint buildup as they become an obstacle.

Please don’t use duct tape, as it loses adhesion fast and doesn’t seal gaps well.

Step#11: Connect the remaining duct sections

Now connect other duct sections. Just like the first one, insert them into the crimped ends of the elbow joints. Please do this for all of them and hold the ends together using metal foil tape.

Insert the crimped end of the last elbow joint into the duct cap section and tape it.

Step#12: Screw the vent to the wall

The next step is to screw the vent to the wall. First, drill pilot holes on the wall for the screws to pass. Push drywall anchors into the spots to support the fasteners. Then, place a U-shaped pipe strap around the duct.

After that, insert the screws with a screwdriver to hold the duct. Place a pipe strap every 6 to 8 feet of straight duct to minimize the strain on the taped joints.

Step#12: Plug in the washer

Now, plug in the washer. You can turn it on when you’re ready. Then check outside to ensure the vent flap is opening.

Why Should You Vent A Washing Machine Drain Pipe?

A washing machine drain vent is necessary because it lets in air. That prevents a vacuum from forming in the drain, which can affect wastewater removal.

Depending on the building code in your region, you may not need a vent. But you’ll need to have a gap around your drain tube. It’ll prevent the vacuum from forming in the drain. That way, it won’t interfere with the water flowing out.

Lack of venting can also cause your washing machine to drain slowly and overflow.

However, ensure you use a drain trap (P-trap). That’s because it seals sewer gases and prevents them from getting into your house. The gases contain harmful microorganisms that can cause problems when inhaled.

Some sewer gases are also flammable. So, it may lead to a fire hazard if you don’t have a drain trap.

It’s proper to vent your washing machine once you install a drain trap. That’s because negative pressures can also pull the water out, making the P-trap useless. And unless you’re ready to get constant overflows, you have to vent your washer.


A washing machine vent is essential because it prevents improper outflow of water. It also prevents overflow, sluggish performance, and noise.

A properly installed vent will help the P-trap function properly. That way, you won’t have hazardous sewer gases enter your home.

You can install the vent yourself. All you have to do is buy the necessary materials and tools. Then follow the guidelines for installation. If it seems too overwhelming, you can contact a professional.

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I have always been a shopaholic. A lot of times my questions went unanswered when it came to retail questions, so I started Talk Radio News. - Caitlyn Johnson

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