For numerous years the codes have required that all bathrooms either had a window OR a light & mechanical exhaust system be installed (see legal section below). The thought process was the homeowner could either open the window to remove certain obnoxious gasses &/or the excessive moisture or turn at least turn on a fan if that option wasn’t available.
 2009 IRC – R303.3 Bathrooms. Bathrooms, water closet compartments and other similar rooms shall be provided with aggregate glazing area in windows of not less than 3 square feet, one-half of which must be openable.Exception: The glazed areas shall not be required where artificial light and a mechanical ventilation system are provided…Quick reminder – R308.4.2.5 Hazardous locations (requiring tempered glass, etc…): The following shall be considered specific hazardous locations for the purposes of glazing: Glazing in enclosures for or walls facing hot tubs, whirlpools, saunas, steam rooms, bathtubs and showers where the bottom exposed edge of the glazing is less than 60 inches (5’) measured vertically above any standing or walking surface. (exception granted for those 5’ or more away from said item) |
Generally we have to dig through insulation to spot this issue inside the attic, in this case it was quite easy to spot…
For those that were not located where a window was possible, (or for builders tired of callbacks with rotted trim) one might assume that most contractors would follow all the manufacturer’s directions & vent the fixture outside…
Well, they would be sadly mistaken as the industry standard in most areas was to simply let it dump into the attic or even between the first & second floors. Part of the issue was that while the electrician had to install/wire up the fan, that was the extent of his involvement & the HVAC contractor was generally only hired to handle the Heating & Air Conditioning portion.
 While the codes allow for either windows or mechanical ventilation in a bathroom, with today’s tighter buildings, an exhaust fan should be installed on a timer in all bathrooms. There are not too many people that will open up a window when it is freezing outside leading to a ton of moisture being dumped into the house. The other issue is for those that do, is remembering to shut it later or shutting it too early. |
The codes to the rescue:
Just like the dryer vents, duct leakage testing, etc… where the codes used to be silent on this issue; they now mandate that the Builder / Mechanical Contractor actually ventilate said exhaust outside.
- R303 (Exception cont.) Ventilation air from the space shall be exhausted directly to the outside.
- M1501.1 Outdoor discharge. The air removed by every mechanical exhaust system shall be discharged to the outdoors.
- M1507.1 General. Where toilet rooms and bathrooms are mechanically ventilated, the ventilation equipment shall be installed in accordance with this section.
- M1507.2 Recirculation of air. Exhaust air from bathrooms and toilet rooms shall not be recirculated within a residence or to another dwelling unit and shall be exhausted directly to the outdoors.
Along those lines & seeing common sense isn’t so common they also state that;
- R303.4.2 Exhaust openings. Exhaust air shall not be directed onto walkways.
- M1501.1 Air shall not be exhausted into an attic, soffit, ridge vent or crawl space.
- M1507.2 Exhaust air from bathrooms and toilet rooms shall not discharge into an attic, crawl space or other areas inside the building.
Sizing a bathroom fan can be somewhat tricky as the information out there is all over the place. Some are quite simply based on Square Footage, some account for volume, while others simply give you a set number for each item in your bath. Per the codes the minimum size must be at least 50 CFM for those controlled by a switch or timer.With that said, that only accounts for what the fan is rated for & does not account for the resistance in moving the air through & out of the exhaust duct. Along those lines most also don’t take into account jetted tubs or steam showers which release a lot more moisture in the air which requires more air to not only exhaust it from the bathroom but through the line.So with that I recommend: (Width x Length x Height / .8) / Factor
So a 6’ x 8’ bath with 8’ tall ceilings would require a fan with 60 CFM while one with a steam shower should be around 80 CFM. Ahhh but what happens if you have a true Master Bath (let’s just say around 200+ SF) with a steam shower? Do you really need a 300+ CFM fan that can suck the towel off your head? The answer can be both yes & no based on the design & layout. |
The Duct:
Unlike the “dryer vent” section the code is pretty quiet on what can be used & how it should be run. This leads to a lot of the nice pictures you have seen and some interesting “practices” from groups that should know better. The biggest concern is to make sure the water vapor & any possible condensation issues are directed outside & not allowed back into the house.
- If at all possible the exhaust port on the fan needs to be pointing straight at where you are going to run & terminate the exhaust
- Eliminate as many bends or fittings as possible – while some like using 90’s to gain height or change direction, 2 – 45’s will do a better job & not add as much resistance.
- The most optimal location to exhaust the air is out the gable end (remember soffits & ridges are off limits as they can allow the moisture back into the attic)
- Just like a dryer, the smoother the pipe the better (I prefer PVC & yes the joints need to be glued)
- If the gable end is over 16’ to 20’ away, the roof might be a better option (this generally also allows you to have the needed pitch without requiring a you to use elbows or fittings to artificially raise it.
- Just like other ducts & vent-lines, it must be supported every 4’. (For PVC running directly out, simply grab some ½” foam board & cut in 2” x 6” wide pieces. Place one at the end & then every 4’ in add in additional pieces – this will give you a 1/8” per inch slope in the line from the fan to the outside allowing any condensation that may form in the line to flow outside the building.)
- No matter where you terminate the line, a louver, screen &/or other damper should be installed which not only prevents the wind from blowing in but will also help prevent insects & other creatures access.
- If you wish to use insulated flex duct (not recommended) you should use 6” line with an adapter)
- Any ventilation going through uninsulated / unconditioned spaces should be insulated to help eliminate condensation issues (not only that which may form inside the pipe / but also on the exterior)
- If you do use metal duct with a seam, the seam should be facing up & taped with approved tape
The PVC pipe visible is the bathroom exhaust without the spacers under it yet
| One of the big questions is just how long should I let the exhaust fan run. As a general rule it should be running while you take your shower & 15 minutes afterwards. The biggest issue is getting the water vapor out of the air – so if you take cooler showers it may not require 15 minutes, while someone taking a very hot shower might need 20 minutes. This is just something you have to monitor & gauge for yourself. Another option is to buy one of the newer fans which includes a humidistat in it so it can decide when it needs to turn on & off. I got to say I am not fully sold on those yet. Ready for a real trip – who says you need to run the exhaust at all, especially during the winter months? |
How about vent-less or recirculation types?
Seeing I popped this picture in this last weeks “Wacky Wednesday” series… the answer is they are not allowed. Per M1507.2 “Recirculation of air. Exhaust air from bathrooms and toilet rooms shall not be recirculated within a residence or to another dwelling unit and shall be exhausted directly to the outdoors.” Just remember the goal of a bathroom fan is to exhaust obnoxious gasses & moisture resulting in a healthier, safer living environment. Heh, wonder how long until they figure that out in regards to Kitchen Exhaust?
Is a heating element required by 2013 code in bathrooms?
I have never heard of that though your local building department might, I highly doubt it, but they are whom I would check with
We are remodeling the historic Snyder Mercantile here in Tenakee Springs, Alaska. The whole upstairs of this 130′ long building is a residence and roof penetrations are to always be avoided here in snow and ice country. If we use oversize pipe and vent towards the closest gable can we use very long runs of pvc? I would think some inline flapper valves might help keep the flow directional if several bathrooms share an exhaust duct.
Single residence or… If single I would go with an inline fan and you would really need to talk with the manufacturer to get it spec’d out properly. Most dealer reps I have dealt with are really good / know someone to call (Fantec, Broan, Panasonic) to help make sure your needs are met.
If multifamily, I would probably also go with an inline fan though I think you would have to have one for each residence if memory serves me correctly.
The nice thing with an inline fan is there is no noise as the fan is located close to the gable & you can get larger motors to meet the specific requirements needed for long runs & multi-rooms
When running the PVC to the gable I have a screen there at the gable now. Do I need to cut a hole in screen to put the PVC outside of the screened gable opening or can I just end the PVC at the gable screen? Thanks
It sounds like you would be running the vent pretty high & as pointed out above you don’t want it running for a long length and should keep down any bends. If you do have it leaving the insulation it should also be insulated.
It really should vent directly outside & your building inspector may or may not allow what you are considering. With that, compared to many cases where they are never vented this is definitely an improvement & shouldn’t cause any issues in most cases
Greetings, I am rebuilding an old house and adding exhaust to all the bathrooms. My second story windows overlooking the back of the house look out on about part of the roof for the first floor. The roof extends about 12 feet out from the second story and is about 16′ wide. Questions, is there a required (or recommended distance) the vent should be from the upstairs windows?
Thanks! Bill
Sorry I don’t have my code book handy but 6′ is ringing a bell. One other item to consider is which way does the wind primarily blow – in this case (esp. if you open the windows) you may want to be further away if the wind would be blowing it towards the windows
quick question. home built in 07 and the exhaust vents through the soffit. I guess it was code at the time in my area. well now I want to do this the right way through the gable end but the attic trusses are in the way. should i go over the trusses in this instance? any help would be recommended.
Good question & on this one I really have to ask where you are located & how far is the run – in Phoenix I see no issues, colder climates you are definitely looking at needing insulation & maybe even that might not be enough in some instances like Minneapolis that had 37 days below 0 in a row. As pointed out above & the dryer exhaust piece, bends add resistance which effectively reduce the length you can run the exhaust. If in doubt I would look at running it out at the roof as close to the fan as possible
i am renovating my bathroom just wondering how far my exhaust fan should be from my heating duct
Interesting question & I don’t recall anything in the code books on that & I have seen plenty that are almost side by side. With that you should make sure that both are well sealed (I would hate to be sucking the exhaust fumes back into the furnace / AC) & insulated to help prevent any dew point issues which also happens to be code for runs in attics & other unconditioned spaces
can i vent a bathroom fan into a next-door furnace room? Or, can i share the same ventilation duct that exists in the furnace room to get the bathroom air to the outside, or does the bathroom fan require its own hole?
Nevermind – found my answer. This is a big huge no no. Didn’t think about the potential of a blocked furnace room vent and what that would do to the poisonous gasses in my scenario (it would send them right back into the bathroom!). I will give the bathroom fan its own separate hole.
No problem & glad you found the proper answer
can i vent a bathroom fan into a next-door furnace room? Or, can i share the same ventilation duct that exists in the furnace room to get the bathroom air to the outside, or does the bathroom fan require its own hole?
can i vent a bathroom fan into a next-door furnace room? Or, can i share the same ventilation duct that exists in the furnace room to get the bathroom air to the outside, or does the bathroom fan require its own hole?
Nevermind – found my answer. This is a big huge no no. Didn’t think about the potential of a blocked furnace room vent and what that would do to the poisonous gasses in my scenario (it would send them right back into the bathroom!). I will give the bathroom fan its own separate hole.
No problem & glad you found the proper answer
I have two bathroom, neither of which currently have a bathroom fan. Could I use one hole out of my roof instead of cutting two? The longest run would be under 7ft. Thanks in advance.
What you may wish to consider than is what is called a remote or shared fan – Instead of the having a fan in both bathrooms, both simply have the exhaust ducts ran to one fan which would pull air from both baths when turned on. The nice thing about this is you will find it generally more quite in the bathrooms, though with that short of a run, the noise reduction might not be as noticeable
Another option is going with a dampered lines, but any issues with the damper can redirect the air flow from one bath to the other
I have a new fan installed, need to run it about 3′ to the nearest wall (in an insulated attic space, in New England) – but perpendicular to the exit port of the fan and the direction of the rafters. This means I need to raise the vent pipe above the rafter and then turn it 90 degrees and run 3′-4′. Suggestions? Do I need to put anything in place to ‘catch’ the condensation where it will be rising as soon as it leaves the unit?
If you refer to the “Dryer vent” article I mentioned above https://thehtrc.com/2013/common-sense-building-dryer-venting) we do discuss what happens with very sharp corners & how much effective length each one adds. You may wish to visit your local plumbing/HVAC supply house & see if they have any pipes or vents with a longer sweep. Depending on the exact layout you maybe able to get by with 2 45’s (one angled up & then the other angled to the wall).
Ahh condensation, this probably won’t be an issue as long as the effective run is short, fan is sized properly & ran for an appropriate amount of time. With that is should also be insulated to help prevent any issue (I prefer making sure mine is buried deep in cellulose & mounded above as needed)
I have a house built in 1994 with 2 bathrooms upstairs with
fans vented in the soffits. After years
of moisture in the attic due to moist air coming back into the attic via the
soffits (mostly noticeable in the winter time), I had a contractor re-run the 2
vents (separately) from the fans to the gable end of the house, each
around 10 to 15 feet away from the gable
to the vent. Flex was used from the fan
to the attic floor (very short run) and then transitioned to rigid metal all
the way to the vents on the gable ends. Runs are pitched down, and the vents have a
flap on them on the outside of the house.
Each run is covered with insulation (seems like fiberglass with a plastic
outer covering). This seems to work, no
more moisture that I notice in the attic in the winter. But, I have found the end of the insulation
inside the plastic covering around the conduit at the gable end (where it vents
outside) are wet. The fiberglass is wet,
and at one point in the winter, I could feel ice chunks in the
fiberglass/plastic insulation around the conduit. I do not think moisture is coming back into
the attic at the gable vent and going into the fiberglass insulation around the
conduit. I think either the conduit has
a seem, and moisture is escaping out of the seem into fiberglass, or somehow
where the vent is near the cold gable side of the hours, moisture in the
conduit collects between the outside of the conduit between the fiberglass
insulations. Any thoughts on how to find
and correct the problem? I hate to take
the insulation all off unless I can buy new insulation that is split so I can
re-cover the conduit and tape it back up.
You may wish to see how well you’re connection is (maybe add tape – see below0 & seal that appropriately along with any seams (which are hopefully pointed up) by simply pulling back the fiberglass covering. If you refer to our duct sealing article that might help out. https://thehtrc.com/2011/air-sealing-duct-system
If you need to remove & replace the foil covered insulation, you may wish to check at your local building supplier – whether it is a Home Depot, Lowes, Menards, Ace, Tru Value or lumber yard. As for removing & replacing, it isn’t split, but you would disconnect the connection, slide it on & then reattach.
I wish the author had said something about how exactly he made the transition from the 3 7/8″ exhaust port on the fan to the 4″ interior diameter of the PVC pipe.
Ahh thanks for letting me use one of my favorite lines from Star Wars – all to easy – I used a pipe connector like you see where I joined two sections of PVC together. You may also wish to check the manufacturers directions &/or attachments included as they may have included or have available a fitting for that. In this case it was plastic to PVC with a little PVC cement
Hi, Great post!
Questions:
1. When you say “pipe connector” do you mean a 4″ pvc coupling?
2. What did you use for an outside vent connector/coupling? and/or how did you connect it to the 4″ pvc? I’ve been looking for an outside vent block that would work – transitioning to 4 inch pvc – making sure that any condensation runs ALL the way out…
Many thanks &
1. yes for this unit it was a perfect fit, for others as I said, some manufacturers have transition pieces
2. I popped the metal piece out and the pipe as I recall slid into the “click” section perfectly
I have an old bathroom I’m remodeling (1957), without an exhaust fan. I’m adding one, but it is far from the gables. The rest of the house has already been remodeled and added on to, and seems to be up to CA code. The exhaust fan is about 4′ away from the range hood exhaust ducting. Would there be any problem with tapping into that ducting, which then runs directly out the roof? I’d rather not put another hole in my roof.
Good morning & in short – yes there are major issues with that as pointed out by comments from JBH below. Sorry while I hate putting holes in the roof myself, sometimes it is the best option if done right, not a worry at all
Hello, I have a log cabin with an upstairs bathroom. The vent fan is cut into a plywood side wall. It vents straight up and out of the roof. The run is only a couple of feet. Unfortunately, the old fan runs counter clockwise and exits out of the top right. All replacements, I can find, run clockwise and exit top left. Any suggestions?
Panasonic has a ton that vent out the right side & some that vent left… The catch might be the depth though – do you still have the older unit as many times you can simply replace the fan unit itself (with a quitter more efficient one) while leaving the case intact
I have an aluminum damper for my sidewall termination, any suggestions on how to join a 4″ PVC duct pipe to this? If I bevel the inside of the PVC I should be able to insert the aluminum duct into the PVC pipe, how can I then seal this since I’m pretty sure the PVC cement won’t bond to the aluminum. It’s a very short run, less than 4′ total with 2 45 deg elbows (dormered backwall so I needed to drop the vent down a few inches behind an interior wall and then out. Thanks.
I would not bevel the inside of the pipe, but would use a coupler like I did for the main connection. As for the connection, I would go with a GeoCel or some sort of elastomeric caulking with one or two light beads run all the way around the metal before inserting it & probably finish it off with one at the edge
You can also seal with metallic ventillation tape or strong duct tape, as long as you overlap the aluminum and PVC, so no moisture can affect the bond of the tape.
Uh yes but no – yes you can use UL listed metallic tape meant for ducts but longevity between two different materials is questionable. As for “duct tape” the answer is flat out no… As the saying goes duct tape has a 1001 uses but using them on ducts is definitely not one.
I have a straight shot outside but it’s about 20 ft. away. Is that ok?
Well as mentioned above 16′ to 20′ is generally the maximum I recommend but I have gone up to 25′ with no issues – just watch your slope
Hello,
We need to replace our old bathroom exhaust fans. Two of them are located on the second level; I am not certain, but I am assuming that they currently vent into the attic–as does the microwave/stovetop (Illinois home built in 1999). If I am correct, do we need to make them vent outside now-is that the code for my area?
Also, our downstairs 1/2 bathroom vents outside just at the front door! Craziness. That would be considered a walkway, yes? Lastly, I am unclear as to how many air changes per minute is required. I have read, 12, 8, or 5. What is recommended?
Thank you so much for your time.
~~~Marilyn
My pleasure & yes if you replace them, you must bring the assembly up to code. I would also do it to prevent any issues from cropping up even if you don’t. As for the front door – not the best way to great guests but your building inspector is highly unlikely to have you move it as it is exiting the structure & it is considered existing…
As for air changes – please see the tip area above for my recommendation. There is no exact requirement on how much is required with the exception of the minimum size required for all bathrooms.
Hi, I am adding a new vent + exhaust fan to my home as part of a basement remodel. The vent will service a basement laundry/utility area (dryer vent is separate) about 12 ft. away from the exterior wall. Unfortunately, the best place to exit the 4″ vent out of the house is below a kitchen window (about 4 ft. below), and adjacent to a basement window, about 2 ft. to the side. I know with the Furnace exhaust, this would not be acceptable. But, will this be ok for a simple room vent? Thanks in advance.
–Geoff in Seattle, WA
The best person to ask first is the building inspector – will they accept it or not. Beyond that you know the uses, how often windows are open, etc… Sometimes one is just faced with making the best choice for the situation.
With that though I am wondering why you do think one is needed – are you line drying clothes or other items in there? The dryer itself will easily pull 200 CFM of air out when running if vented properly. Washing the clothes should not release that much moisture especially if you are using cold water. I know in our area many do this but that is generally because they are using this one for a whole house exhaust system.
I have railroaded bathrooms (one 3/4, one full). The 3/4 bath is internal and full bathroom is on an external wall. I am considering a solar tube for the 3/4 bath with a vent through the roof. Is that practical? Is it more economical to vent both bathrooms with one duct going to the external wall?
Good question – first I love solar tubes but I am not sure I would trust or be able to recommend a combo unit like that. As for common venting, I would recommend checking into solutions like the one from fantec that has one motor located near the exit point & pulls air from both bath rooms when the three way switch/timer is on. While you can vent both bath rooms using a common line the potential for issues is high with that type of system and I would recommend avoiding
Hi, I would like to install a bathroom vent fan, but if I run a 4″ pipe the termination it would look really bad on the exterior while a 3″ would be able to fit nicely. The bathroom has a window so installing a fan is optional. I know I would lose some air flow, but does the IMC have anything to say about reducing from 4″ to 3″?
Thanks,
Sam
Not that I recall but I would have to punt to the local building inspector on this. You may ask if it is possible to run a 4″ pipe for the bulk of the distance and then reduce down.
Hello,
I need to add a fan to a bathroom with a low slope roof. Directly underneath the bathroom is a crawlspace. Can I put the fan in the wall and run the ducting down to the crawlspace and out underneath the deck?
Uh probably not as the deck would be considered a walkway (though as I always say check with your local building official to be sure) – beyond that there is nothing to prevent you from using a crawlspace as a way to run the vent
I’m venting two bathroom exhaust lines (PVC) through a single opening through brick construction. Any recommendations on appropriate Y connectors would be greatly appreciated. Thanks in advance!
A trip to your local supply house with measurements and a diagram would be your best bet but don’t forget you would need dampers to help prevent one from blowing into the other. A better solution might be a system with one fan that pulls from both bathrooms at the same time – they can be a little tricky to install but performance wise they cant really be beat. The only one I have experience with is FanTech but there are numerous options out there
SLS,
I recently gutted my second floor for renovation. During wiring for the new bathroom, my electrician ran the bathroom exhaust flex tubing to discharge beneath one of the roof vents (see photo). This is not directly outside, but is close. Is this ok? Thanks! Erik
Sorry I didn’t see this one sooner, but no. Right now you are hoping on a wish and a prayer that it will exhaust outside much less not fill up with water
SLS,
I recently gutted my second floor for renovation. During wiring for the new bathroom, my electrician ran the bathroom exhaust flex tubing to discharge beneath one of the roof vents (see photo). This is not directly outside, but is close. Is this ok? Thanks! Erik
SLS,
I recently gutted my second floor for renovation. During wiring for the new bathroom, my electrician ran the bathroom exhaust flex tubing to discharge beneath one of the roof vents (see photo). This is not directly outside, but is close. Is this ok? Thanks! Erik
Sorry I didn’t see this one sooner, but no. Right now you are hoping on a wish and a prayer that it will exhaust outside much less not fill up with water
You paid someone for that? dear lord. just run it out to the side of the house. the condensation in that flex will build up, and it will fill up with water. Any moisture exhaust should be ran slightly downward. Yours is completely upright.
Need to add exhaust fans to downstairs bathroom; home doesn’t already have one. Best way to do that? Brick house with crawl space.
We just had a brand new roof installed on the shed dormer about a month ago. For the past few days we noticed water dripping from the vent fan. My hope was that it was just condensation, so I opened up the fan to see what’s up. Long story short, the contractor didn’t have the exhaust vent 100% sealed. So for the better part of a a month, our attic has been filling hot,moist air. Since our attic is inaccessable, I had to pull down a sheet of drywall. The rafters, joists and decking were as wet as they could be. There were even standing puddles of water on the foam insulation! I’ve got a fan blowing up to hopefully dry things out- the contractor will be getting a phone call from me on Monday!
I am using 4″ schedule 40 pvc pipe thru cold attic space to vent a bathroom exhaust fan. Does it need to be insulated?
Sorry I missed seeing this till now – the answer is it depends and most revolves around common sense as the codes (as I recall) are silent on this. If you live in a hot climate then you probably don’t have to worry about it. If you live in a cold climate & have it buried under cellulose or something similar then also probably not – not covered, cold climate… unless you like having water drip back inside or down the exterior wall – yes indeed you need some
I found this article while looking for code on bathroom exhaust vents. I’ve got a slightly different issue. Our bathroom fans all vent to the outside of the home, on the same side as the furnace burner exhaust. Just a few minutes ago i detected furnace exhaust fume smells in that room, and am wondering if the negative pressure in the home created by an open fireplace damper is sucking furnace exhaust back through the fan flue. There are no other vents in that room and the door was closed. I put a CO detector in there to see if it picks up anything, but i doubt it will.
Any thoughts?
Good morning & while I got to admit that almost anything is possible, I doubt it was due to negative pressure pulling fumes back in across two dampers on a completely separate exhaust system. My guess is the wind was just right or you might have gotten a whiff from the ducts supplying the forced air throughout the house (and as the door was closed).
As for using a CO detector – it is highly unlikely it will ever sound as I mention here – https://thehtrc.com/2013/nest-protect-carbon-monoxide-detector-issues. With that said if you notice the issue again I recommend you have someone come check out the system (which you should be doing at least every few years if not yearly) including the venting as I have seen enough disconnected vents and other issues to fill a book. If it doesn’t I would probably just consider it a fluke.
Sorry I don’t know how I missed this one & hopefully any issues have been addressed. With that if I had to guess highly doubtful your CO detector did pick up anything https://thehtrc.com/2013/nest-protect-carbon-monoxide-detector-issues
With that & assuming the furnace & waterheater are not in the same room… it is possible for fumes to come back in but unless you had a roaring fire going it is highly unlikely that the fireplace damper being open caused such a negative pressure to pull them in especially if the room was sealed. It is more likely you might have a leak in the exhaust piping. You may also want to check that the damper does work on the exhaust vent.
SLS-please help! My house was built 10 years ago and up until now we haven’t noticed anything like this! The ceiling under a second floor bathroom had moisture for about 2 months. We replaced wax ring in toilet, replaced plumbers putty in drains, opened an access panel behind second floor washer and dryer to check behind tub/shower (everything was completely dry), under sink seemed fine and supply lines all looked good. Next to the bathroom is a closet. We removed wire shelving to cut a panel in that drywall and found a vent pipe going up to attic with condensation running down it and dripping in to the ceiling below it. We also noticed that the builder that installed shelving drilled pilot holes though the drywall into the PVC pipe. It is winter here now and very cold. When into attic and everything seemed fine. We can not figure out where it is coming from or how to fix it. Any suggestions? I would love to patch up the drywall and fix the problem!!
Curious is that a vent pipe or radon exhaust pipe – continuous or passive? Besides the obvious of a leaky roof flashing then the issue is you have air reaching the dew point and condensing on the cold pipe which could be coming from almost anywhere – unsealed hole is a plate, leak not visible, the ground below. First fix the PVC pipe and seal any holes / fix any leaks. Run a dehumidifier to help dry it out. If you think you have fixed the issues then you are good to but if not or while you are it above, see about finding some flex duct or something similar to wrap the pipe. That should help keep any moisture away from the cold pipe.
Thanks so much! I will do what you recommended and it will hopefully solve the problem. I think when we cut the drywall out to patch the holes we will just do the flex duct to wrap the pipe before we drywall it back up. Thanks again for the suggestion! BTW-we do not have a radon system in the house.
1920s bungalow with an upstairs dormer bathroom addition in Georgia. We just failed the HVAC inspection because the ceiling exhaust fan is “too close to the window” (about two feet away). Venting isn’t the issue, vents straight out through the roof. The inspector just cites the location. Unfortunately, there isn’t another place to install the fan without completely rearranging the space (including redoing the plumbing). Our contractor claims he’s never heard of this rule and suggests we challenge it. I can’t find any code referencing location requirements of an exhaust fan prohibiting installation near a window. Any thoughts?
M1506.3 (at least in the 15 code book) Exhaust openings shall terminate not less than 3′ from property lines, windows, doors or 10′ from any air intake
As I recall earlier versions were 5′ minimum – find out the minimum required in Georgia & see if extending the pipe might be an option
Thanks – but it’s NOT the exhaust opening or termination point that the inspector sited. It’s the location of the fan itself (i.e. the intake). The exhaust vents far from everything and is completely inline with the code.
But the code does not state that the intake box cannot be near a window.
Got you & in that case yes the inspector is wrong – all that is required per the codes is a window or an exhaust and there is nothing that states the fan must be in X location (except in the bathroom assuming there is no window)
the best way to handle this is to nicely ask the inspector to show you where in the code you are required to place it – in most cases they will realize they made a mistake and this will allow them to save face (which they hopefully will take)
Hi SLS, I’m looking to install a inline extractor in the loft but wanted to know if matter where in inlet from the .bathroom is located – in the bathroom zone 1 or 2 or outside OR doesn’t it matter as no electrics are in the bathroom itself?
If it doesn’t matter where in the bathroom ceiling the inlet is located does the inline extractor in the loft need to have a certain amount of inlet run before the unit itself?
The second part is an easy check with the manufacturer
I am not sure what you mean by Zone 1 or 2 but outside the bathroom is a no. The goal is to extract bad odors, moisture, etc… Most are generally placed close to the shower in a standard size bath while other “spa” like baths may have 2 or more (1 for the toilet/water closet / 1 for the steam shower / 1 general use (bath / sinks / etc…)) It all comes down to what you need to accomplish, the area & layout – if in doubt I would check with the manufacturer as most will willingly help you design a system that meets your needs
Hi,
I want to install a bathroom fan and terminate it at a gable end. What kinds of “termination” are out there for this purpose? Am I looking for “wall vent caps”? Are there such caps anywhere that are more aesthetically pleasing for gable placement? Thanks!
Good morning – There are numerous types out there made from vinyl, brass, stainless to galvanized which you can paint to blend in, in many cases. The traditional ones with the cover sticking out at an angle don’t blend as well as one with a few louvers that sticks out maybe by an inch. You definitely want one with a damper or louvers that close when the fan is not in use. For those that have exhaust only types of ventilation systems, they can get by with one without any louvers and there the choices are more numerous. I would try looking for exhaust wall vent cover
I am to the stage of installing a fan/ light inside of shower stall. To take the place’ and electrical, where a pot light was. I have taken flex exhaust from where it was and was TOLD at the big box stores AND by a prof. electrician that in shower exhaust fan lights were out there. Etc. Now I an being told no there is no such animal. I will apparently have to go with a small ugly f/l and hope for the best. Am in a condo ground level and have little space to work with between my ceiling, pipes, etc. and level above me.
There is such an animal, it just has to be rated to handle moisture and as demand is so low most big box stores, etc… don’t carry them – you would need to look at a specialty lighting store or electrical distributor
I have two bathrooms to vent and originally was going to T the exhausts together and go out the roof. Then I realized one fan would push air into the other, though each fan had a damper that covers 85% of the duct size at the fan itself. Panasonic. Then I read everyone wants it out the side of the house rather than the roof. I live in southern California so there is no snow, mild winters and always between 50-80 deg F. The side of the house is 18 feet away. The roof is 3 feet up. Seems better to go through the roof. What would you recommend?
If you feel comfortable going through the roof – go for it. Personally I like to keep roof penetrations down to a bare minimum. As mentioned above 16 to 20 feet away is about the max distance to run it out a gable end unless you use something like a remote fan & some of those can go a lot higher. In fact you may wish to look into that remote fan as many can handle two or three baths at once (you turn the unit on in one & it pulls from all at once) thus eliminating the T, etc…
In my new home, the basement exhaust bath fan vents out the side of the house. However, when I take a hot shower, after the shower there is a drip from the exhaust fan. When my daughter, who doesn’t take as hot showers, uses the shower, it doesn’t seem to drip. I know they insulated the pipe going out of the house. Any recommendations? I hope we don’t have this problem in the main level showers.
My first question is are you turning the fan on before you start the shower & letting it run afterwards for at least 10 to 15 minutes? Beyond that you might have an issue with how much air is actually being exhausted, & possibly the angle of the run. Besides taking cooler or shorter showers I would make sure you are turning it on a few minutes before your shower & making sure it runs till all the fogging of the mirrors, etc… is gone (generally around 15 minutes). If you still have the issue you might have to get someone in to check the system (and the others) for actual air flow that can go through, etc…
Hello SLS Construction,
I am re-roofing my home with standing seam steel and have a question with my second floor bathroom fan. I have a 6/12 pitch roof with the fan installed in the vaulted ceiling. Which is the better way to exhaust? Thru the roof as close to fan as possible, or run pipe down to soffit (approx 8 ft run)?
Chicago Mark
Through the roof hands down – you never want to exhaust out through a soffit, especially if it is required for venting the attic which would mean pulling that humid air back in
I noticed that the ceiling in my two bathrooms had condensation and that the exhausts were blowing hot air. I realized that the dryer in the laundry room was on when this happened and the contractor told me that he connected the exhaust of the dryer, and the exhausts from the bathrooms together and that all three share one exit to the roof. Is this legal?
No – please see https://thehtrc.com/2013/common-sense-building-dryer-venting – the dryer vent must be independently vented
As for two or more bath vents – yes that is allowable but one should use a specialized system where the fan pulls equally from the two bathrooms near the exit point
Hi,
I am planning to fix exhaust fan for my basement washroom, but I have only place available to keep my vent outside on the wall is beside Furnace exhaust (pipe). I like to know any issues if I fix my washroom exhaust fan close to Furnace exhaust? In fact it will be extended hole with 2 exhaust vent pipes side by side.
One more thing is I have gas input pipe just 20″ away from Furnace exhaust pipe.
Your thoughts inputs will help me in resolving this long time outstanding issues.
Regards,
Venu
What type of furnace exhaust pipe – PVC no issues I see or can think of at that moment. Metal pipe is the issue not only with heat but also a possible issue with galvanic reaction assuming you switch from a PVC style to metal. If in doubt bring in an expert to look at it – there maybe other issues available that you might be overlooking
Thanks for your response, yes its PVC exhaust pipe. I am concerned about having another Vent just beside to it.
From your response I can understand that there is no legal problem around it this. am I correct?
My pleasure – You can always (and I do recommend it anyways) check with the local building department, but no I don’t recall any code issues. There are issues with how close to openings, intakes & windows but with an exhaust being there already…
I have bathroom fans that vent through uninsulated attic. Thin dryer vent tubing was used to vent through roof with lots of loops and bends. Condensation caused problems (of course) and I plan to replace with PVC. The output of my (50 year old maybe) fans are 4 in. diameter. Do I need to use 4 in. wide PVC? Can it be triple wall drainage PVC? It’s a lot lighter and cheaper than regular PVC but it’s slightly ridged on the inside. I’ve got about 16 feet between fan and hole. I don’t understand the part about slanting downhill. From fan to roof is only up. I plan to insulate with wrap and/or great stuff. Appreciate you posting this article.
G’Afternoon – In short ridges are bad, they will simply help trap water. The sloping down is for when you are heading out through a gable end. 16′ is a long distance to blow hot moist air up and then out, you may be better to go with a fan at the exhaust point & make sure you insulate the run
Thanks much. That is what I was afraid you would say. The run would have been much shorter but we now have solar panels in the roof above the bathrooms.
Just noticed when I turn on the bathroom fan in my main bathroom the steam ends up in my bedroom powder room, there is a fan in there that has never worked. We have leaking above a window in one of the bedrooms across from the powder room but only during winter when there’s ice damming above that window We have had the roof and window replaced but that didn’t help. now I’m wondering if the ventilation is the problem. We have vaulted ceilings and no attic. What should we do to find out what is going on??? Where do we start.
Sounds like they connected the baths into one exhaust line (that is a no-no unless you are using a remote fan), assuming it actually exhausts outside. First step is look outside & count vents – is there one or two or… The next item is correcting the issue and reinsulating those areas – that may help correct the ice damming. For more on that: https://thehtrc.com/2013/ice-dams-icicles-attic-condensation
Hi, we are having a home built. We visit frequently to take pictures for our timeline. On our most recent visit we noticed that the exhaust fan ducting from the powder room (no window) which is toward the front of the house, vents to a 45 foot line and exits through the foundation right next to our slider from the kitchen. Do you think that we are being unreasonable to to want them to move the exhaust away from the slider which would be right near our future deck?
Nope & there are codes on how close an exhaust line can be to windows, intakes, etc… Besides I would ask them to show you were the manufacturer allows the setup they used
Thank you!
Good morning, we are in the process of installing a light fan in our upstairs bathroom (as there we no exhaust fan). We thought it would be an easy fix but unfortunately there is no room to vent to back side of the house due to the roof. Do you have any recommendations?
Go through the roof? Trust me that is a viable & sometimes the best &/or only option
Is it allowed to vent the exhaust fan into an unheated attached garage? We live in a condo and they frown on punching holes in the roof or outside walls.
In short no – see above “The codes to the rescue”
Along those lines though, you should not be venting it by walkways or other public areas (also code)
Beyond that generally most will not whine after being shown the applicable code section though they may require you to paint / use a color matched exhaust termination
We are midway through a second floor bathroom renovation in an 1929 house with unfinished un heated attic. the only way we could place the vent fan results in the need to have an elbow from the fan outet up over the floor beams and a second elbow for the run to the outside wall of the ahouse, about 8-10 feet.
i was told by Panasonic tech that we shouldn’t have an elbow within 3 feet of the outlet. we have not other way to vent the fan. what would the problems be with doing this? what would we insultate the solid ducts with? Thanks for your help!
It can add turbulence which could affect the amount the fan can actually expel – sometimes though you got to do what you have to do. With that see if you can do a long sweep, instead of a quick bend – for more on that subject: https://thehtrc.com/2013/common-sense-building-dryer-venting
I will be adding an exhaust fan to an existing basement bathroom and plan to use flex line. Right above the bathroom is the kitchen, where the cooktop exhaust fan duct runs down through the floor near the bathroom, and out the side of the house. Is it legal to tap into the existing cooktop vent if both fans have air backflow flaps to prevent one fan from blowing air through the other? Of course the connection would be at 45 degree angles encouraging the air to exit the home.
Flex is not the best choice but as long as it is rigid it can work. As for tying into another exhaust (especially a kitchen) the answer is NO which I think I did cover above
Hi SLS,
I have had problems with centrifugal inline fans installed in my bathroom which have all periodically failed. To summarise; my bathroom is in the centre of a middle floor flat and the ducting consists of the following :
3m of 100m diameter flexible aluminium hose run from bathroom ceiling down adjacent wall.
From bottom of wall the ducting opens unto 150mm diameter and runs 4m under floorboards.
The ducting run then goes up behind outer wall in 3m (still 150mm) and connects to grilled outer exhaust. So basically the ducting is approx 11m in total length with 5 bends in the system.
The first fan installed was an Acoustic Mini Box 150mm inline centrifugal fan (link removed) this failed after 2 years usage (not sure on failure since was out of warranty, but no problems with moisture etc on connections).
I then installed a second fan which was TD-SILENT Acoustic Inline Mixed Flow Duct Fan 150mm (link removed). This has failed consistently after 4months usage a total of 2 times, I basically have sent it back and got a new replacement each time and they have told me failure not condensation of electrics but motor failure. The third fan replacement has just failed after 4-5months usage.
I am not sure what to do next are all these failures due to the long ducting? Would you recommend the ducting is replaced with a straight run from bathroom through the bedroom next door into external wall? (no access to ceiling in bedroom since bathroom has suspended ceiling, hence why the ducting was run through walls and below floor to avoid run across bedroom) Or have i just been really unlucky with the fans and get a different more reliable inline centrifugal fan which you can recommend?
By the way all the fans were connected to turn on and off with the light switch but had option for timer so terminals looped to bypass this. Also I have observed that when the fans were working I could see steam coming outside from grille when fan was on during shower. Would really like your advise Im stuck!
Thanks
Jason
In short – you effectively have 60′ worth of ducting or almost 20m when you incorporate the bends (assuming not to sharp of bends) – check out dryer venting article which should not be that big of an issue with a decent inline fan
A few quick thoughts – bad motors / fans can be an issue, but multiple vendors… have you checked the electric to make sure it is up to spec?
Shorter runs are always preferable though sometimes not always possible
Is the fan in the center of the run or located towards the end of the run. I always prefer to have it towards the very end with no more turns
I live in a condo building and bathroom fan doesn’t suck out any air. (New fan is installed). Who is the right type of person to trouble shoot the vent?
We have a similar issue with our dryer. If our neighbor runs his dryer, our dryer fills with condensation and wam air from his dryer vs going out the roof vent. (Assume ours does too to his).
Both issues seem concerning. Bathroom for not expelling moisture. Dryer since it’s a gas combustion dryer.
Do we contact an HVAC company for this?
Start with the condo association – beyond that it will probably be an HVAC / Mechanical company
Thanks. I’m on the association board so I know they have as much of a clue as I do! I’ll reach out to an HVAC company.
How many stories is said building – if in high rise you are definitely looking for commercial only that specializes in high rises. If a regular two or three story then a traditional HVAC company should be able to help
Thanks. It’s a smaller building. Two units above ours. Total distance from our ceiling to roof is about 35 feet (loft height ceilings). I’ll call my local HVAC guy.
We hired a contractor to do two upstairs bathrooms and one downstairs over the summer. Now upon a state energy inspection we are told we have extensive mold caused from the fact that our contractors did not do the work according to code and vented all bathrooms into the atic and crawl space! What recourse do we have? In addition to that, we have a huge banging every time we use our hot water as it appears they did not do necessary leveling when they put in floors! what can we do? They will not come back and refuse to admit any wrongdoing. HELP!The mold remediation alone is going to cost over $7K
Unfortunately choosing the wrong contractor can cost you big as you have discovered: To help prevent that we have the following tips – https://thehtrc.com/2008/tips-for-successful-remodeling-project
As you did not list a specific state you are going to have to do some digging:
Help Rescue my Project https://thehtrc.com/2012/help-rescue-my-project has some advice on people to contact – i.e. attorney general / other &/or licensure board assuming your state has one: https://thehtrc.com/2012/residential-contractor-remodeling-licensing-recap – beyond that you will need to contact a lawyer as each state & their provisions vary
As for pipes banging – highly unlikely that is due to a floor not being leveled, generally that is caused by pipe movement or air issues in system
Best of luck
Hi, I have a basement bathroom that I am renovating and will be adding a bathroom vent (it previously did not have any vent). The new vent will run about 2 ft straight to the outside wall. However, the outside wall vent is about 2 feet from the bathroom window and a couple feet from an upstairs bedroom window. Will this be a problem?
Heh do you use those windows – based on the 2018 I-codes the answer is you need a minimum of 3′ from any operable window but it might be worth checking with your local Building inspector as you probably would not be using both the bath window & vent at the same time or may have a modification to said portion of the codes / use another version.
The bathroom in the rental where I live, has neither a window or an exhaust fan, or any type of ventilation. Is this up to code in Oregon?
The only one that can answer this is the local Building Department or maybe even a rental housing authority. Based on most modern codes – no, but when was it built (maybe not required), when was it updated (can stay no or swing to yes) & are there other regulatory items may apply (age doesn’t matter) can swing the answer either way as shown
I live in Texas, and have installed exhaust fan in bathroom. Electricaian has wired fan, b
and… looks like you hit done to early
When running the PVC to the gable I have a screen there at the gable now. Do I need to cut a hole in screen to put the PVC outside of the screened gable opening or can I just end the PVC at the gable screen? Thanks
It sounds like you would be running the vent pretty high & as pointed out above you don’t want it running for a long length and should keep down any bends. If you do have it leaving the insulation it should also be insulated.
It really should vent directly outside & your building inspector may or may not allow what you are considering. With that, compared to many cases where they are never vented this is definitely an improvement & shouldn’t cause any issues in most cases
Is a heating element required by 2013 code in bathrooms?
I have never heard of that though your local building department might, I highly doubt it, but they are whom I would check with
Greetings, I am rebuilding an old house and adding exhaust to all the bathrooms. My second story windows overlooking the back of the house look out on about part of the roof for the first floor. The roof extends about 12 feet out from the second story and is about 16′ wide. Questions, is there a required (or recommended distance) the vent should be from the upstairs windows?
Thanks! Bill
Sorry I don’t have my code book handy but 6′ is ringing a bell. One other item to consider is which way does the wind primarily blow – in this case (esp. if you open the windows) you may want to be further away if the wind would be blowing it towards the windows
quick question. home built in 07 and the exhaust vents through the soffit. I guess it was code at the time in my area. well now I want to do this the right way through the gable end but the attic trusses are in the way. should i go over the trusses in this instance? any help would be recommended.
Good question & on this one I really have to ask where you are located & how far is the run – in Phoenix I see no issues, colder climates you are definitely looking at needing insulation & maybe even that might not be enough in some instances like Minneapolis that had 37 days below 0 in a row. As pointed out above & the dryer exhaust piece, bends add resistance which effectively reduce the length you can run the exhaust. If in doubt I would look at running it out at the roof as close to the fan as possible
i am renovating my bathroom just wondering how far my exhaust fan should be from my heating duct
Interesting question & I don’t recall anything in the code books on that & I have seen plenty that are almost side by side. With that you should make sure that both are well sealed (I would hate to be sucking the exhaust fumes back into the furnace / AC) & insulated to help prevent any dew point issues which also happens to be code for runs in attics & other unconditioned spaces
I have two bathroom, neither of which currently have a bathroom fan. Could I use one hole out of my roof instead of cutting two? The longest run would be under 7ft. Thanks in advance.
What you may wish to consider than is what is called a remote or shared fan – Instead of the having a fan in both bathrooms, both simply have the exhaust ducts ran to one fan which would pull air from both baths when turned on. The nice thing about this is you will find it generally more quite in the bathrooms, though with that short of a run, the noise reduction might not be as noticeable
Another option is going with a dampered lines, but any issues with the damper can redirect the air flow from one bath to the other
I have a house built in 1994 with 2 bathrooms upstairs with
fans vented in the soffits. After years
of moisture in the attic due to moist air coming back into the attic via the
soffits (mostly noticeable in the winter time), I had a contractor re-run the 2
vents (separately) from the fans to the gable end of the house, each
around 10 to 15 feet away from the gable
to the vent. Flex was used from the fan
to the attic floor (very short run) and then transitioned to rigid metal all
the way to the vents on the gable ends. Runs are pitched down, and the vents have a
flap on them on the outside of the house.
Each run is covered with insulation (seems like fiberglass with a plastic
outer covering). This seems to work, no
more moisture that I notice in the attic in the winter. But, I have found the end of the insulation
inside the plastic covering around the conduit at the gable end (where it vents
outside) are wet. The fiberglass is wet,
and at one point in the winter, I could feel ice chunks in the
fiberglass/plastic insulation around the conduit. I do not think moisture is coming back into
the attic at the gable vent and going into the fiberglass insulation around the
conduit. I think either the conduit has
a seem, and moisture is escaping out of the seem into fiberglass, or somehow
where the vent is near the cold gable side of the hours, moisture in the
conduit collects between the outside of the conduit between the fiberglass
insulations. Any thoughts on how to find
and correct the problem? I hate to take
the insulation all off unless I can buy new insulation that is split so I can
re-cover the conduit and tape it back up.
You may wish to see how well you’re connection is (maybe add tape – see below0 & seal that appropriately along with any seams (which are hopefully pointed up) by simply pulling back the fiberglass covering. If you refer to our duct sealing article that might help out. https://thehtrc.com/2011/air-sealing-duct-system
If you need to remove & replace the foil covered insulation, you may wish to check at your local building supplier – whether it is a Home Depot, Lowes, Menards, Ace, Tru Value or lumber yard. As for removing & replacing, it isn’t split, but you would disconnect the connection, slide it on & then reattach.
Hello, I have a log cabin with an upstairs bathroom. The vent fan is cut into a plywood side wall. It vents straight up and out of the roof. The run is only a couple of feet. Unfortunately, the old fan runs counter clockwise and exits out of the top right. All replacements, I can find, run clockwise and exit top left. Any suggestions?
Panasonic has a ton that vent out the right side & some that vent left… The catch might be the depth though – do you still have the older unit as many times you can simply replace the fan unit itself (with a quitter more efficient one) while leaving the case intact
I have an old bathroom I’m remodeling (1957), without an exhaust fan. I’m adding one, but it is far from the gables. The rest of the house has already been remodeled and added on to, and seems to be up to CA code. The exhaust fan is about 4′ away from the range hood exhaust ducting. Would there be any problem with tapping into that ducting, which then runs directly out the roof? I’d rather not put another hole in my roof.
Good morning & in short – yes there are major issues with that as pointed out by comments from JBH below. Sorry while I hate putting holes in the roof myself, sometimes it is the best option if done right, not a worry at all
I wish the author had said something about how exactly he made the transition from the 3 7/8″ exhaust port on the fan to the 4″ interior diameter of the PVC pipe.
Ahh thanks for letting me use one of my favorite lines from Star Wars – all to easy – I used a pipe connector like you see where I joined two sections of PVC together. You may also wish to check the manufacturers directions &/or attachments included as they may have included or have available a fitting for that. In this case it was plastic to PVC with a little PVC cement
I have an aluminum damper for my sidewall termination, any suggestions on how to join a 4″ PVC duct pipe to this? If I bevel the inside of the PVC I should be able to insert the aluminum duct into the PVC pipe, how can I then seal this since I’m pretty sure the PVC cement won’t bond to the aluminum. It’s a very short run, less than 4′ total with 2 45 deg elbows (dormered backwall so I needed to drop the vent down a few inches behind an interior wall and then out. Thanks.
I would not bevel the inside of the pipe, but would use a coupler like I did for the main connection. As for the connection, I would go with a GeoCel or some sort of elastomeric caulking with one or two light beads run all the way around the metal before inserting it & probably finish it off with one at the edge
I have a new fan installed, need to run it about 3′ to the nearest wall (in an insulated attic space, in New England) – but perpendicular to the exit port of the fan and the direction of the rafters. This means I need to raise the vent pipe above the rafter and then turn it 90 degrees and run 3′-4′. Suggestions? Do I need to put anything in place to ‘catch’ the condensation where it will be rising as soon as it leaves the unit?
If you refer to the “Dryer vent” article I mentioned above https://thehtrc.com/2013/common-sense-building-dryer-venting) we do discuss what happens with very sharp corners & how much effective length each one adds. You may wish to visit your local plumbing/HVAC supply house & see if they have any pipes or vents with a longer sweep. Depending on the exact layout you maybe able to get by with 2 45’s (one angled up & then the other angled to the wall).
Ahh condensation, this probably won’t be an issue as long as the effective run is short, fan is sized properly & ran for an appropriate amount of time. With that is should also be insulated to help prevent any issue (I prefer making sure mine is buried deep in cellulose & mounded above as needed)
I have a straight shot outside but it’s about 20 ft. away. Is that ok?
Well as mentioned above 16′ to 20′ is generally the maximum I recommend but I have gone up to 25′ with no issues – just watch your slope
Hello,
We need to replace our old bathroom exhaust fans. Two of them are located on the second level; I am not certain, but I am assuming that they currently vent into the attic–as does the microwave/stovetop (Illinois home built in 1999). If I am correct, do we need to make them vent outside now-is that the code for my area?
Also, our downstairs 1/2 bathroom vents outside just at the front door! Craziness. That would be considered a walkway, yes? Lastly, I am unclear as to how many air changes per minute is required. I have read, 12, 8, or 5. What is recommended?
Thank you so much for your time.
~~~Marilyn
My pleasure & yes if you replace them, you must bring the assembly up to code. I would also do it to prevent any issues from cropping up even if you don’t. As for the front door – not the best way to great guests but your building inspector is highly unlikely to have you move it as it is exiting the structure & it is considered existing…
As for air changes – please see the tip area above for my recommendation. There is no exact requirement on how much is required with the exception of the minimum size required for all bathrooms.
Hi, I am adding a new vent + exhaust fan to my home as part of a basement remodel. The vent will service a basement laundry/utility area (dryer vent is separate) about 12 ft. away from the exterior wall. Unfortunately, the best place to exit the 4″ vent out of the house is below a kitchen window (about 4 ft. below), and adjacent to a basement window, about 2 ft. to the side. I know with the Furnace exhaust, this would not be acceptable. But, will this be ok for a simple room vent? Thanks in advance.
–Geoff in Seattle, WA
The best person to ask first is the building inspector – will they accept it or not. Beyond that you know the uses, how often windows are open, etc… Sometimes one is just faced with making the best choice for the situation.
With that though I am wondering why you do think one is needed – are you line drying clothes or other items in there? The dryer itself will easily pull 200 CFM of air out when running if vented properly. Washing the clothes should not release that much moisture especially if you are using cold water. I know in our area many do this but that is generally because they are using this one for a whole house exhaust system.
The best person to ask first is the building inspector – will they accept it or not. Beyond that you know the uses, how often windows are open, etc… Sometimes one is just faced with making the best choice for the situation.
With that though I am wondering why you do think one is needed – are you line drying clothes or other items in there? The dryer itself will easily pull 200 CFM of air out when running if vented properly. Washing the clothes should not release that much moisture especially if you are using cold water. I know in our area many do this but that is generally because they are using this one for a whole house exhaust system.
I have railroaded bathrooms (one 3/4, one full). The 3/4 bath is internal and full bathroom is on an external wall. I am considering a solar tube for the 3/4 bath with a vent through the roof. Is that practical? Is it more economical to vent both bathrooms with one duct going to the external wall?
Good question – first I love solar tubes but I am not sure I would trust or be able to recommend a combo unit like that. As for common venting, I would recommend checking into solutions like the one from fantec that has one motor located near the exit point & pulls air from both bath rooms when the three way switch/timer is on. While you can vent both bath rooms using a common line the potential for issues is high with that type of system and I would recommend avoiding
Hello,
I need to add a fan to a bathroom with a low slope roof. Directly underneath the bathroom is a crawlspace. Can I put the fan in the wall and run the ducting down to the crawlspace and out underneath the deck?
Uh probably not as the deck would be considered a walkway (though as I always say check with your local building official to be sure) – beyond that there is nothing to prevent you from using a crawlspace as a way to run the vent
Uh probably not as the deck would be considered a walkway (though as I always say check with your local building official to be sure) – beyond that there is nothing to prevent you from using a crawlspace as a way to run the vent
Need to add exhaust fans to downstairs bathroom; home doesn’t already have one. Best way to do that? Brick house with crawl space.
Hi, I would like to install a bathroom vent fan, but if I run a 4″ pipe the termination it would look really bad on the exterior while a 3″ would be able to fit nicely. The bathroom has a window so installing a fan is optional. I know I would lose some air flow, but does the IMC have anything to say about reducing from 4″ to 3″?
Thanks,
Sam
Not that I recall but I would have to punt to the local building inspector on this. You may ask if it is possible to run a 4″ pipe for the bulk of the distance and then reduce down.
I’m venting two bathroom exhaust lines (PVC) through a single opening through brick construction. Any recommendations on appropriate Y connectors would be greatly appreciated. Thanks in advance!
A trip to your local supply house with measurements and a diagram would be your best bet but don’t forget you would need dampers to help prevent one from blowing into the other. A better solution might be a system with one fan that pulls from both bathrooms at the same time – they can be a little tricky to install but performance wise they cant really be beat. The only one I have experience with is FanTech but there are numerous options out there