Simply put, NO. You cannot (by code) and should not (by practical reasoning) share exhaust venting between a kitchen exhaust and a bathroom exhaust fan.

Can you run two vents one duct?

If you have two bathrooms that are close together and one has an exhaust fan and the other doesn’t, you might be wondering if you can tie a new exhaust duct into the existing one. Well, you can’t! You’d often blow air from one bathroom into the other, and local building inspectors wouldn’t approve it.

Can exhaust fans share a duct?

When the exhaust fan is operating, the back-draft damper is pushed open by airflow to allow air to exit through the exhaust duct. Figure 2. Exhaust fans in separate dwelling units can share a common exhaust if each exhaust fan is equipped with a back-draft damper to prevent cross contamination.

How far can you run a bathroom exhaust fan duct?

Generally a 4 inch flex duct can carry a fan exhaust for up to 25 ft. Most codes require that.

Can you use dryer duct for bathroom fan?

You can’t use a dryer vent duct for the bathroom fan. This is against building codes because it’s unsanitary, poses a fire safety risk, and will not function properly. It’s best to have an independent duct for the bathroom fan.

Can kitchen and bathroom Share vent?

Simply put, NO. You cannot (by code) and should not (by practical reasoning) share exhaust venting between a kitchen exhaust and a bathroom exhaust fan.

Can you tie bathroom exhaust into plumbing vent?

The answer is no way! Sewer gas is explosive and could settle back into your exhaust fan which has an electric motor that is not rated for explosive gases. You’re now not at code for the sewer or the fan.

What is code for bathroom exhaust fan?


Residential code: R303 Ventilation air from the space shall be exhausted directly to the outside. Mechanical code: M1501. 1 Outdoor discharge. The air removed by every mechanical exhaust system shall be discharged to the outdoors.

Does each bathroom fan need its own vent?

It must vent outside. The issue is if you put two fans and connect them with a Y duct connector, it is easy for one fan to exhaust its air into the other bathroom.

Does a bathroom exhaust fan need to be vented outside?

Bathroom fan installation requires outside ventilation. If the fan isn’t accessible through an attic, you’ll need to vent through a sidewall of your house. These types of ducts and vents are typically installed when the house is built.

Can I use flex duct for bathroom fan?

The flexible insulated duct is recommended for this application to minimize condensation in bathrooms (or other warm and moist areas), and can also be helpful in reducing fan noise.

Can you use foil duct for bathroom fan?

Use rigid metal ducting (aluminum or galvanized steel) with lengthwise seams facing up and joints sealed with foil tape or duct mastic, or rigid plastic pipe. Be sure to slope the duct a bit for drainage to the exterior.

Do I have to use an insulated duct for bathroom fan?

To properly vent a bathroom fan to the outside of your house. Most warm climates do not require that bathroom vent piping be insulated. It would be best to use insulated exhaust piping to create a direct and safe exit route in some cold climates. Most bathroom fans need a 3″ or a 4″ vent pipe to pass through.

Can you use PVC to vent a bathroom fan?

I’d seriously consider using foam core PVC pipe as the vent pipe for your fan. The fittings can be glued, and any water that might form in the pipe will never leak onto your ceiling or down a wall.

Should kitchen exhaust duct be insulated?

You can insulate your vent hood duct, but it’s not required. Insulating your vent hood duct will keep the noise down and keep your greasy kitchen air from escaping into your joists and attic.

Does vent pipe need to be insulated?

It is best if your kitchen exhaust fan discharges to the outdoors and do not exhaust into the attic and soffits or crawl space. If the run is long, you will require a big fan, so check with a professional. The joints should be sealed, and if the duct runs through an unheated space, they need to be insulated.

Can I vent my range hood into the attic?

No, you should never vent your range hood into the attic. The excess buildup of grease and moisture in your attic will ruin it and over time may cause mold damage. Instead, vent your hood through an interior wall or through the ceiling all the way outside of your home.

How do I keep my vent stack from freezing?

A common method is to attach an insulated sleeve over the outside end of the vent pipe. These sleeves not only insulate the vent pipe but also extend it higher into the air. The intent is to keep the water vapor and gases above the freezing point until they exit the end of the vent pipe.

Can you pour hot water down sewer vent?

So can you pour hot water down the sewer vent- Simply YES. You can. Hot water is the best solution for those who live in areas where the temperature is below freezing or where snowfall causes clogs in the vent pipe. Just pouring the hot water can help to melt the ice present inside the sewer vent stack.

Does a plumbing vent have to go through the roof?

The answer is, no, plumbing vents do not have to go through the roof. While roof stacks are the most common form of plumbing vents, you can run a plumbing vent through an exterior wall. The stipulation is that the plumbing vent has to run higher than the highest window of the house.

Does a toilet need a vent stack?

“Does a toilet need a vent?” And the answer is yes, your toilet has to have a vent. For more information on the great importance of plumbing vents, read our plumbing vent article here. And the size of this vent pipe depends on your local plumbing code.