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How To Install Bathroom Vent Through Roof

Caulk And Nail The Roof Vent

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

Once the collar is adequately dry-fitted and secured to the roof, you can move on to mounting the roof vent over the duct connector. You will also have to install the side/upper flanges underneath the roof shingles.

However, before inserting the roof vent, you will have to do some caulking. In other words, youll need to cover the underside of the vent flange with a bead of exterior caulking.

One very important thing to point out here is that you shouldnt caulk the bottom portion only the side and upper flanges. To prevent condensation from taking place , you will need to keep the bottom flange free of caulking.

The next thing youll have to do is nail the roof vent. Once the cap is inserted, take a couple of rust-resistant roofing nails and hammer them into the roof vents flange. Do the same thing with the roof sheathing.

Make The Wire Connections

  • From the bathroom, unscrew and remove the blower motor from the vent fan housing. Save the screws.
  • Next, unscrew the built-in receptacle from inside the housing to expose its wiring. Again, save the screws.
  • Use wire nuts to join same-color wires with the ones from the electrical cable you fed into the housing in Step 5: white to white, black to black.
  • Wrap the bare copper wire under the green grounding screw inside the housing and tighten the screw.
  • Place the electrical receptacle back into position and secure it with the two screws removed from it earlier.

Do I Need To Duct My Exhaust Fan To The Outside

What does the BCA say? Below are two statements:

1) If the roof is not lined with sarking material and is clad with roofing tiles or decking with adequate air leakage to the outside, fans can be mounted in the ceiling exhausting into the roof space.

2) If the roof is lined with sarking material then the air needs to be ducted to the outside atmosphere.

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Consider Venting Through The Wall Instead

If you are intent on doing your bathroom vent project yourself, then you may want to consider an option that is less fraught with potential disaster.

An alternative to venting through the roof can be to vent the bathroom through the wall instead. This method is less likely to result in a leak, and you dont have to mess with the integrity of your roof.

If the situation of your bathroom lends itself to venting through a wall rather than the roof, then it would most certainly be a much simpler project than going through the flat roof, and you should seriously consider this alternative.

How To Install A Bathroom Vent Through The Roof

Venting Exhaust Fans Through the Roof

If you are tired of that steamy bathroom after your shower, or have install bathroom vent on your DIY list for your home, weve got some tips that will help you do it correctly and avoid some common mistakes that could cost you big in the long run.

If youre thinking that you can use an existing vent, or even just vent into the attic, youll want to stop right there! If you plan to tap into an existing vent pipe, you could block the venting of the original source and create big problems at that location. Now, if youre thinking about venting into the attic, youve got some problems just around the corner. You will be venting warm, humid air into your attic which is not a good idea, as it raises the temperature of your attic. As well, venting that warm, humid air into your attic in the winter causes even more humidity and moisture to collect in the attic, leading to possible damage to your attic, walls, and potentially worse.

Now that we are on the same page with What Not To Do, lets get that vent installed!

  • Figure out where you will install the vent
  • Pick the spot in your bathroom where you want to install the vent.
  • In the attic, make sure there are no obstructions for the vent pipe from the bathroom ceiling to the roof .
  • Its a good ideA to drill a hole from the attic into the bathroom ceiling to mark your installation location.
  • Mount the vent into the ceiling
  • Cut the hole overhead in the ceiling .
  • Install the vent into the ceiling.
  • Attaching the vent pipe
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    Ducting Requirements In A New House

    All new houses are built to certain energy efficiency regulations, which means that for new builds statement 2 is applicable. In practical terms this means that new roofs are sealed and will therefore need your ventilation system to be ducted to the outside. This could be in the form of an eave vent, roof mounted cowl or an external wall vent. Ventilating from a moisture laden bathroom into a fully sealed roof will mean that the moisture will have no way of escaping, which could have long term adverse effects on your roof. Moisture trapped within the roof structure can result in long term corrosion of metal, timber rot, loosening of nails as timber swells, and cladding rot or swelling which can result in costly rectification work.

    If you have an older house you may have a tiled roof with no sarking material covering the underside of the tiles. Without this full coverage your roof will not be as energy efficient, but will have small gaps between the tiles that allow for entry and exit of air passively. These gaps mean any moisture laden air will have the opportunity to escape. This does not mean that you cannot or should not duct your system to the outside, in fact you may still wish to do so. Especially if you have a roof with ample space and its easy enough to put in a vent under the eave.

    Diy Costs To Replace A Bathroom Extractor Fan

    Replacing a bathroom exhaust fan yourself costs $20 to $400 for the new fan and takes 2 to 3 hours. Select a fan that matches the existing air duct’s size for the least complicated installation.

    Installing a completely new bathroom fan is not a DIY project. It requires professional experience, tools, ductwork, electrical wiring, cutting through the walls or ceiling, and sometimes cutting through the roof.

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    Dry Fit Roof Vent Hood

    After you have cut out the top shingle layer for the main vent body, you should dry fit the roof vent. You will have to break the seal of the surrounding top and bottom shingles using a prybar so that the metal flange can go underneath the top layer.

    Only the top and side portion of the metal flange should go underneath the shingles. The bottom portion of the flange should be above all shingles.

    Read Also: How To Fix A Noisy Bathroom Fan?

    Types Of Bathroom Vent

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

    The older 3 duct hose prefer by most bathroom enthusiasts, such as the Broan 688. Many bathroom fans of today recommend the 6, 5, or even 6 duct hose. Make sure to check with your manufacturer to determine which vent hose you should choose. While you can still use a smaller vent hose for bathroom fans, it will not perform well and may have lower-rated specs. Some exhaust fan covers for soffit vent fans have adapters that can be used with 4, 5, or 6 ducting. You can purchase plastic adapters to connect your bathroom fan to a 3 51 hose if it has a 4-inch outlet. If possible, it recommends that you follow the manufacturers recommendations.

    Insulated vent hose

    Insulated vent hoses recommend for attics that have no seal, such as unfinished attics or foam insulation. These vent hoses have insulation on the outside. Insulated bathroom vent hoses will prevent condensation from forming outside the vent. Your attic air will remain as cold as the outside during winter. Your bathroom vent sends warm, conditioned air from the inside to the outside when it is open. Water forms when two temperatures meet, similar to when you drink iced lemonade outdoors on a hot day. The water will then be on the outside of your glass.

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    Install The Duct Connector Or Collar

    A duct connector is a small section of metal piping that connects the flexible duct hose to the roof vent.

    At least one side of the duct collar is usually crimped which gives some space for the duct hose to easily slide into the collar. Once the duct hose is sealed to the duct connector with foil tape , the other end of the duct connector can be inserted into the roof hole.

    Duct connector

    You will likely need a helper who can hold the duct collar through the roof hole while you secure it to the roof. When you are on the roof, you should cut at least two tabs in the collar so you can nail it to the roof.

    How To Vent Bathroom Fan Through Flat Roof

    The precise method for installing a bathroom fan vent through a flat roof will vary depending on your individual circumstances and the situation of your bathroom. Your project may require additional steps to complete the project, so we will only discuss the basic steps that would be needed to get the job done.

    Recommendation: Installing a bathroom fan vent through a flat roof is a big undertaking that can have negative ramifications for your home. It is recommended that you secure the services of a professional to do the installation rather than attempting it yourself!

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    Do I Need A Vent Fan If I Have A Window

    If you have an operable window, you still will benefit from a bath vent fan. It was common in older homes for a bathroom to have a window for ventilation. Window ventilation is referred to as passive ventilation. However, for windows to be effective, they need to be open, which isnt practical in hot, cold, or rainy weather.

    Building codes for new construction now require mechanical ventilation even with an operable window. Proper bathroom ventilation helps control mold growth and prevent related health problems that an open window cant.

    A bathroom ventilation system is still a good idea for existing homes, even where building codes are not required.

    Do Bathroom Exhaust Fans Need To Be Vented Outside

    Use an In

    Bathroom exhaust fans require outside ventilation through a sidewall, roof, or behind a gable or soffit vent. Venting a bathroom fan into the attic, garage, or any space within the house causes moisture damage, wood rot, and mold problems.

    The best bathroom exhaust vent location is the building side, away from any overhangs. Roof venting is also common but is more susceptible to leaks.

    10 feet

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    Do Bathroom Fans Need To Be Vented Outside

    Bathroom fans are designed to remove moisture and odors from the air in your bathroom. The fan pulls air from the room and exhausts it outside through a vent. This helps to keep the air in your bathroom fresh and prevents mold and mildew from growing.Most bathroom fans are vented to the outside, but there are some that are not. If your fan is not vented to the outside, it will simply recirculate the air back into the room. This can actually increase the humidity in the room, which can lead to mold and mildew growth. It is therefore important to make sure that your bathroom fan is properly vented if you want it to be effective at removing moisture and odors from the air.

    How Do I Install A Bathroom Fan Without Attic Access

    Installing a bathroom fan without attic access

  • Mounting your new bathroom exhaust fan. Another thing you’ll want to do is to make sure you have the ability to mount your new bathroom exhaust fan to a ceiling joist.
  • Attach the duct connector to the duct.
  • Connect the electrical wires.
  • Test out your new bathroom exhaust fan.
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    Leaks From Structures Through The Roof

    Similar to the typical sloped shingle roof found in residential construction, flat roofs are vulnerable to leaks where an in-home structure rises through the roofs surface. Not only do you have the problem of the actual leak, but you also have to contend with potentially moisture-sensitive fixtures being exposed to water.

    Some protective measures for avoiding this scenario are flashing installation, as previously mentioned, and rain collars to keep rain and melted snow from entering through venting. Roof boots are fitting for residential projects and can cover vent pipes to seal any openings from water to leak into.

    How To Replace A Bathroom Fan

    Bathroom fan roof vent kit install – Broan RVK1A vent
    • If you already have an exisiting bathroom fan installed and need to change it out, this informative video gives you step-by-step instructions on installing a bathroom fan replacement.

    Tip: Keep your bathroom fan running 15 to 20 minutes after showering or bathing. This will dry up any moisture in the air and prevent mold and mildew.

    Installing a vent fan in your bathroom can eliminate moisture and help freshen the air. Whether your current bathroom fan is noisy, or you need to install an entirely new fan system, we have everything you need to make the job easier. If you prefer to leave the job to a professional, take advantage of our bathroom installation services.

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    Where Do You Vent A Bathroom Exhaust Fan

    There are a few things to consider when venting a bathroom exhaust fan. The first is where the fan will be located. It is important to have the fan close to an exterior wall so that the ductwork can be installed properly. The second thing to consider is the size of the fan. Make sure that the fan is large enough to adequately ventilate the bathroom. The last thing to consider is how you will route the ductwork. There are many different ways to do this, so it is important to consult with a professional before beginning your project.

    Bath Vent Fan Wiring Connections

    Typically the bathroom vent fan motor is powered by the bathroom ceiling light fixture circuit some installers, particularly in hotels or rental units, hard-wire the bath exhaust vent fan to force it on when the bathroom ceiling light is on – thus assuring that the vent fan is in fact used. If the bath vent fan is noisy this forced-on status can annoy everybody.

    In the simplest case there will be just three fan wires to connect: black to black , white to white , and ground to ground, typically a bare ground in the house wiring to a green ground wire in the fan housing wiring set.

    The most general fan wiring instructions will state: “Hook up the bath vent fan wiring by removing the electrical junction box cover. Next connect the house wires to the fan wires: ground to ground, neutral white to neutral white, and hot black to hot black.”

    But when the fan includes also a light and perhaps an electric heater there are actually three circuits to complete, each with its own controlling switch.

    At BATHROOM FAN WIRING you will find detailed electrical wiring connections for a typical fan, light, & heater combination vent fan system, adapted from installation instructions for the Delta Breez Model RAD80L installation manual and other bath fan installation guides cited there.

    Bathroom Vent Fan Ductwork Insulation

    This topic has moved to a new article

    Bath Exhaust Fans Routed Up Through the Roof

    This discussion is now found at BATHROOM VENT UP THROUGH ROOF

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    How To Install A Bathroom Fan



    Over 1 day

    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.

    Whether you need to install a new wall bathroom exhaust fan or a ceiling bathroom exhaust fan, bathroom fan installation is a project you can do yourself. This guide gives you step-by-step instructions on how to install a new bathroom fan in the ceiling, including creating a new roof exhaust point if you are dealing with new construction.

    Cut A Hole In The Roof And Remove Shingles

    How to Install a Bathroom Vent Fan

    Now it’s time to cut a hole in the roof.

    • Trace a circle on the underside of the roof just large enough for the roof vent and tailpipe.
    • Drill a hole large enough for the saw blade, then cut out the circle with a reciprocating saw, saber saw or keyhole saw.
    • Remove the shingles from around the cutoff without damaging the underlying roof paper.

    Tip: A major part of a bathroom fan replacement project involves working on your roof. Excercise caution when you use a ladder to climb up on the roof and while you are working there.

    Read Also: Does Insurance Cover Storm Damage To Roof

    Irc Section M1601 Duct Construction

    IRC M1601.1 Duct Design

    Duct systems serving heating, cooling and ventilation equipment shall be installed in accordance with the provisions of this section and ACCA Manual D, the appliance manufacturer’s installation instructions or other approved methods.

    Flexible plastic vent fan ductwork: shown at above left is a common use of un insulated, flexible ventilation fan duct. In this installation the duct is improperly installed, spilling directly into the attic space of the building.

    This duct material is least costly at the time of installation but may be most costly when a combination of accumulated condensation and duct damage leaks into the building insulation or ceiling cavity.


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