Should bathroom exhaust fan be vented in attic? (2022)

Asked by: Allan Keebler

Score: 4.9/5 (45 votes)

Bathroom exhaust fans perform an important function by removing excess moisture from your home. When venting a bathroom exhaust fan, make sure to vent the air to the outside, rather than into your attic where it can cause mold and mildew to form.

Is it OK to vent a bathroom exhaust fan into the attic?

The Code of Bathroom Exhaust Fans

Air shall not be exhausted into an attic (except whole house ventilation), soffit, ridge vent or crawl space.

What is code for venting a bathroom 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.

Should bathroom exhaust fans be vented outside?

Note that the bathroom vent fan must always exhaust to the outdoors; never allow the duct to simply blow into an attic, crawlspace or other enclosed area.

What happens if you don't vent a bathroom exhaust fan?

Your bathroom, much like your kitchen, tends to hold a lot of moisture. This isn't a problem in most houses, as long as the moisture and odors are vented outside. It can lead to excessive condensation and moisture, which can cause mold and mildew. ...

(Video) Can you exhaust bathroom Ventilation Bath Fans into Attic Episode 108

17 related questions found

What do you do if your bathroom has no exhaust fan?

If your bathroom doesn't have a fan, take advantage of the door and window(s) to let out steam. Whenever weather permits, open the window during your shower or bath and leave the window open for at least 15 minutes after you exit.

How do you vent a bathroom fan into the attic?

The fan exhaust must vent directly to the exterior of the home. Do not put the vent termination in a roof overhang or soffit. Don't put it on a wall near or under a roof overhang. The moist air that's belched out by the fan can be sucked right up into the open soffit vents and be drawn into your attic.

Do bathroom vents have to vent outside?

Bathroom fan installation requires outside ventilation. ... Letting the fan exhaust into an open attic will cause moisture buildup on the underside of the roof. Avoid venting through a soffit vent or ridge vent.

Is it OK to vent a bathroom fan through the soffit?

A bathroom fan can be vented through soffit so that the warm air from the bathroom comes out through it and goes outside. However, It is important to keep in mind it can not be vented into the soffit, as this will lead moisture back into the attic.

(Video) Bath fan venting into the attic and what to do about it

Is it OK to vent bathroom into attic?

While venting the bathroom into the attic isn't a good idea, there's nothing wrong with venting it through the attic. This means allowing the flexible duct from the bathroom to pass through the attic space, going to a vent in the gable end, soffit or roof.

What is code for bathroom vent fan?

Bathrooms. Section 1203.4. 2.1 of California's building code requires all bathrooms with a bathtub, shower, spa or similar fixtures to be ventilated by an exhaust fan. The fan must be Energy Star-compliant and vented to the outside.

How far can you run a bathroom exhaust fan vent?

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

Do I need a separate vent for each bathroom fan?

A bathroom vent is an essential part of your home's ventilation system. Bathroom exhaust fans remove moisture, heat and odors from the bathroom. Even if they are right next to each other, two bathrooms should not share a vent. Each will need its own exhaust fan.

Can you vent a bathroom vent into the attic?

No, you cannot vent your bathroom exhaust fan into the attic. You should never exhaust the bathroom fan directly into the attic. ... It is almost always required by code that the exhaust fans vent on the outside of the home with no air leaks into the interior of the home.

(Video) How to Vent a Bath Fan Through the Roof | This Old House

Can you vent bathroom fan into soil pipe?

To be more constructive, NO, NO, NO, NO and NO again, you cannot vent anything into a soil pipe. Either go through the wall behind the extractor or run flat ducting to left/or right of extractor on top of cabinets to an alternative external wall.

Is it better to vent bathroom fan through roof or soffit?

Whether it's new construction or a remodel, a bathroom vent should always vent through the roof instead of an eave, overhang, or soffit. ... However, natural air flow from the outside will bring the moist air back into the attic through the soffit vents, kind of like a vacuum.

Can I vent an exhaust fan into the attic?

It's never okay to vent directly into the attic EVEN IF you're attic is vented. Most municipalities require extractor and exhaust fans to be vented to the outside of the building with an vent cap. Excessive moisture will cause condensation on roof members and insulation.

Can 2 bathroom fans share a vent?

Bathroom fans can share a common vent. Both fans must be of similar capacity and have back-draft dampers installed. The duct must be over-sized by one inch for every additional fan added to the system. Let's dig a little deeper on how to install two bathroom fans in a common vent.

How do you vent a bathroom with no outside access?

The easiest way to vent a bathroom with no outside access is to install a ceiling vent, but you have other options to consider, too. You can also add more ductwork, get a floor vent, or just use a fan to add extra airflow during your projects.

(Video) How To Install Roof Vents. Bathroom Fan Vents, Attic Ventilation Etc. -Jonny DIY

Is there a bathroom fan that doesn't vent outside?

Install a recirculating fan in a half-bath. This type of bath fan doesn't exhaust air to the exterior. Instead, it passes bathroom air through a filter medium that removes odors. A recirculating bath fan would be a workable option for a half-bath because there's no shower to fill the space with moisture.

What do you do if your bathroom doesn't have a vent?

No Vent? How To Keep An Older Bathroom Dry

  1. Open the door and windows. One of the simplest solutions to a moisture problem in the bathroom is to keep the door and window open while you're in the shower. ...
  2. Hook up a fan. ...
  3. Wipe down the walls. ...
  4. Dry towels elsewhere. ...
  5. Plug in a dehumidifier.

Can plumbing vents terminate in the attic?

Yes, a plumbing vent can terminate in the attic. But it must have an air admittance valve at the termination to keep noxious sewer gas fumes from rising into the attic. ... Also, the air admittance valve must be at least 6-inches above the attic insulation, and there must be at least one other vent that extends outdoors.

Is it OK to vent range hood into attic?

It is definitely not a good idea to vent a range hood into the attic. Ideally, the range hood should be vented to the outside, usually through the roof. This requires installing some ductwork, but is worth the extra work and expense.

Can I use PVC for bathroom exhaust fan?

Some high-quality fans come with special one-piece insulated flexible piping that prevents condensation and leaks. ... 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.

(Video) Properly Vented Bath-Fans and Insulation Mistakes

FAQs

Should you vent a bathroom fan into the attic? ›

Can I Vent A Bathroom Fan Into My Attic? No, you should not vent a bathroom fan directly into an attic. The problem with venting into the attic is that the moisture-rich air may form droplets on the wood sheathing, insulation, rafters, and ceiling joists, leading to mold growth.

Should I vent my bathroom fan through the roof? ›

Bath fan exhaust can and does cause massive mold blooms and wood rot in attic spaces. The fan exhaust must vent directly to the exterior of the home. Do not put the vent termination in a roof overhang or soffit. Don't put it on a wall near or under a roof overhang.

Do bathroom exhaust fans 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.

How do you vent a bathroom with no outside access? ›

Installing a ceiling vent is probably the most efficient way to ventilate a bathroom with no outside access. A ceiling vent is a unique machine that allows air to escape from the bathroom. In other words, it's a machine that, like an open window, allows moisture to escape from your bathroom.

Where do you vent a bathroom fan in the attic? ›

When venting a bathroom exhaust fan, make sure to vent the air to the outside, rather than into your attic where it can cause mold and mildew to form. Options for venting a bathroom exhaust fan include (best to worst): Through the roof or an exterior gable wall.

Is it better to vent bathroom fan through roof or soffit? ›

Whether it's new construction or a remodel, a bathroom vent should always vent through the roof instead of an eave, overhang, or soffit. The point of a bathroom exhaust vent, or any vent really, is to remove hot, moist air from the house.

Is it OK to vent bathroom fan through soffit? ›

A bathroom fan can be vented through soffit so that the warm air from the bathroom comes out through it and goes outside. However, It is important to keep in mind it can not be vented into the soffit, as this will lead moisture back into the attic.

Can you vent a bathroom fan into plumbing vent? ›

1 of the International Residential Code (IRC), you are not allowed to vent a bathroom fan into a plumbing vent: “The air removed by every mechanical exhaust system shall be discharged to the outdoors in accordance with Section M1504.

What is the point of a ductless bathroom fan? ›

What is this? Ventilation is your bathroom's best defense against the growth of mold and damage to the other parts of the room. Charcoal filtered ductless bathroom fans work to remove unwanted odors and keep the air in the bathroom moving, while being energy efficient and often quite quiet.

What is the code for bathroom ventilation? ›

M1505.

Exhaust air from bathrooms and toilet rooms shall not be recirculated within a residence or circulated to another dwelling unit and shall be exhausted directly to the outdoors. Exhaust air from bathrooms, toilet rooms and kitchens shall not discharge into an attic, crawl space or other areas inside the building.

Where does the air from the bathroom fan go? ›

Purpose of the Extractor Fan

The fan sucks in air from the bathroom and blows it out of through a vent that is runs behinds above the ceiling. It works in the same way that a kitchen exhaust hood does except moisture is being moved instead of smoke.

Can I use a dehumidifier instead of a bathroom fan? ›

A dehumidifier is designed to collect and remove moisture, not necessarily ventilate a bathroom. Some dehumidifiers do pump in dry air, but these humidifiers are part of a greater HVAC system. A regular, portable home dehumidifier cannot be used instead of a bathroom fan.

How long can a bathroom exhaust fan run? ›

Experts agree that you should not leave your bathroom fan on all night. You should only run the fan for about 20 minutes during and after a bath or shower. You especially shouldn't leave it on at night. If it's run too long, it can cause serious problems and become a potential fire hazard.

Is it OK to exhaust into 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.

What kind of pipe do you use to vent a bathroom fan? ›

PVC Schedule 40 Foam core pipe is the ideal pipe for bathroom fan venting. This type of piping is non-toxic, easy to install, and is code compliant. The PVC pipe fittings can be safely cemented and sealed, preventing any water that might collect in the pipe from leaking and causing water damage.

Can you vent range through soffit? ›

You must not vent into the soffits, or even under the soffits unless you are more than a foot and a half below the soffit to allow the wind to dissipate the moisture before it rises back up into the attic.

How do you vent a bathroom fan in cold climate? ›

The common solutions to this ice problem are to use a higher-powered fan, use a larger-diameter, shorter duct run, and wrap the pipe with better duct insulation. You can also run the fan longer (at least 10 to 15 minutes after showering is a good baseline) so the ice melts or doesn't freeze in the first place.

Can plumbing vents go to soffit? ›

Venting Into the Soffit is Prohibited

The reason is that the soffit is considered part of the indoor space and unless you are going to be fitting an air admittance valve (AAV), plumbing vents cannot terminate indoors.

How do you run an exhaust fan duct? ›

Bathroom Exhaust Fan Ductwork - YouTube

How do I know if my soffit is vented? ›

Vented Soffit vs. Non-Vented Soffit - YouTube

How can I improve my bathroom ventilation without windows? ›

Here are a few solutions.
  1. Purchase an Exhaust Fan. Extractor or exhaust fans are the most common method of ventilating a windowless bathroom. ...
  2. Install a Fresh Air Supply Vent. ...
  3. Exhaust Fan + Air Supply Vent. ...
  4. Use a Dehumidifier. ...
  5. Install a Ceiling Fan. ...
  6. Install an Air Conditioner. ...
  7. Keep the Bathroom Door Open. ...
  8. Use a Regular Fan.

Why is my bathroom exhaust fan not pulling air? ›

Check if the exhaust duct is connected to the fan; it could be disconnected. Check the flapper in the exhaust vent hood; it could be jammed. Check if your fan is actually a recirculating fan, which filters out odors instead of removing moisture.

Can a bathroom exhaust fan be too big? ›

Yes, your bathroom fan can be too big. A bathroom exhaust fan that is much too large for the area will only increase your energy bill, fill your space with cold air in the winters, and ultimately, not perform its job effectively. In this case, bigger is not always better.

How many CFM do I need for a 8x10 bathroom? ›

Example: How much air is in an 8×10 bathroom with an 8 ft ceiling? In this example, we need a fan that will change 640 cubic feet of air 8 times per hour (it will vent through the exhaust fan). How minimum CFM should such a bathroom fan produce? In 1 hour, the total airflow should be 640 ft3 × 8 = 5,120 ft3.

How much does it cost to install a exhaust fan in bathroom? ›

Bathroom exhaust fan installation costs $150 to $550 to replace an existing fan. The cost to install a new bathroom fan is $250 to $950 to vent the fan outside through the wall or roof. The toilet extractor fan itself costs $20 to $400, depending on the type and features.

Do you need a vent in a bathroom with a window? ›

You do not need a fan in a bathroom with a window, but it is recommended for proper bathroom ventilation. Exhaust fans remove the excess moisture in your bathroom more efficiently than an open window alone.

Does a bathroom exhaust fan need to be insulated? ›

The bathroom exhaust duct should be insulated when it passes through an unconditioned space. This means that the temperature of the space is not controlled. Most exhaust ducts run through an unheated/cooled attic and must be insulated to prevent condensation inside and outside of the duct.

Can you use dryer vent duct for bathroom fan? ›

A bathroom fan and a dryer should never share the same vent. International building code states that dryer vent exhaust systems must be separate from all other systems and must expel moisture out of the house through a dedicated vent.

Do bathroom fans push air in or out? ›

Yes, any time you operate a bathroom exhaust vent fan you are removing stale (conditioned) air from inside and replacing it with outdoor air.

Where do most bathroom vents go? ›

You can place the fan directly over the bathtub or shower base, but it's sufficient to position it anywhere near the bathing area. If the bathroom has both a tub and shower, or a shower and a whirlpool tub, the fan should go somewhere between the two fixtures.

Does exhaust fan bring in fresh air? ›

The primary function of an exhaust fan is to help extract the impure air and bring in fresh air thereby improving the air quality. They are also an efficient and affordable installment.

Is it OK to vent bathroom fan into soffit? ›

A bathroom fan can be vented through soffit so that the warm air from the bathroom comes out through it and goes outside. However, It is important to keep in mind it can not be vented into the soffit, as this will lead moisture back into the attic.

Can you vent a bathroom fan into plumbing vent? ›

1 of the International Residential Code (IRC), you are not allowed to vent a bathroom fan into a plumbing vent: “The air removed by every mechanical exhaust system shall be discharged to the outdoors in accordance with Section M1504.

Where should a bathroom fan be installed? ›

You can place the fan directly over the bathtub or shower base, but it's sufficient to position it anywhere near the bathing area. If the bathroom has both a tub and shower, or a shower and a whirlpool tub, the fan should go somewhere between the two fixtures.

Can you vent plumbing into attic? ›

Yes, a plumbing vent can terminate in the attic. But it must have an air admittance valve at the termination to keep noxious sewer gas fumes from rising into the attic.

How do you vent a bathroom fan through the roof? ›

How to Vent a Bath Fan Through the Roof | This Old House - YouTube

How far can a bathroom vent run? ›

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

How do you properly vent a bathroom? ›

Bathroom fans should always vent outside rather than through the ceiling and into your attic. Venting your bathroom fan into a wall cavity or attic runs the risk of mold growth. Building codes require new homes to vent bathroom fans outside the house.

Can I use PVC pipe for bathroom vent? ›

PVC piping is an excellent material to use for venting your bathroom fan as long as the correct type of pipe is used. PVC creates a better seal than metal, so you won't experience any problems with leakage as you could with using metal ducting pipes.

Can a bathroom exhaust fan be too big? ›

Yes, your bathroom fan can be too big. A bathroom exhaust fan that is much too large for the area will only increase your energy bill, fill your space with cold air in the winters, and ultimately, not perform its job effectively. In this case, bigger is not always better.

Does a ductless bathroom fan remove moisture? ›

Ductless bathroom fans are good at their intended purpose of mitigating odors. Ductless bathroom fans are quiet and energy-efficient solutions but they will not remove moisture.

Does a bathroom fan need to be on its own circuit? ›

Bathroom Circuits

If the vent fan has a built-in heater, it must have its own 20-amp circuit. This is called a "dedicated" circuit because it serves only one appliance or fixture. Heat lamps, wall heaters, and other built-in heating appliances may also require dedicated circuits.

Can a plumbing vent run horizontal in the attic? ›

Can Vent Pipes be Horizontal? There is no problem with running your vent pipes horizontally as long as you remember that there should be a minimum clearance of 6 inches above the spill line.

Does a vent pipe have to go straight up? ›

Do Plumbing Vent Pipes Need to be Straight? Plumbing vents need to be straight on the vertical. This is necessary to avoid any vapor locks from occurring. When there is a bend in the vent pipe, moisture accumulates and is trapped.

How high should a vent be above a roof? ›

The International Plumbing Code (IPC), requires plumbing vent pipes to extend vertically at least 152 mm (6 in.) above a roof, per Section 905.5, "Vent Connections and Grades." Additionally, vent pipes must be at least 305 mm (12 in.) away from a vertical surface.

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