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If your main reason to not vent is that you don’t like the way the soffit vents look, I have to say that’s not a good enough reason. They’re hardly noticeable, so common they’re standard, and no one really ever looks up there or cares except tradespeople, from what I can guess. But you may have other reasons. I like the advice of Scooter and Mike here. If you choose to not vent the house, you’ll have to follow a rigid system for this, as Mike said, follow a menu. Check the archives if that is the case, there is a fair amount of discussion on the +,- of this argument.
MD
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Wedgehead, Vent those soffits, it is my opinion of course, but that has been my experience with homes built in the Sierras. Checking with the local building code and the officials that enforce it is a good idea too. Good luck.
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The vinyl soffit we're using now is Alcoa's Pro-Bead (tm)
SOFFIT/WAINSCOT, it looks like 5" double bead wainscote, so the vents are concealed in the bead detail every 2 1/2", it has a very low profile (3/8") and the J-bead trim is only a 5/8" x 1 3/8" profile.
We're going to use a lot of this.
*yes - the fight goes on - to vent or not to vent - well let me tell you another opinion - you couldn't pay me to NOT vent your house. I'm a firm believer in adequate house ventilation. For me - the main reason is - unless you have an absolute 100% "vapor" tight vapor barrier - you must vent the attic space or the rafter bays in a vault situation. Between showering (batheing), doing laundry, doing dishes, watering plants, cooking etc., etc., etc. a house produces large quantities of water vapor which must be disposed of prior to condensing back to a liquid. I have seen countless examples of under vented and non vented homes requiring varying degrees of repair due to condensing vapors - always vent!!!!!Continuous ridge and soffit vents (period).In addition wedgehead - if you do not intend to vent the ridge - why would you vent the soffits. The only reason to let air in the soffit is to release it elsewhere, there is no point in venting "only" the soffit. If that is your intention - save yourself the time and money - and don't vent at all. Fair warning tho - eventually you will pay!
*Gentlemen. I won't bogg you down with a long discourse on the pros and cons of various attic ventilation devices.For those of you who don't have a copy of my book,_Complete_Building_Construction_ 4th Edition published by Macmillan, I suggest you buy or borrow a copy. Read Chapter 23 Attic Ventilation. The diagrams and windflow patterns through various attic ventilations devices will answer your questions. However, just a few comments.Soffit vents only are balanced and work independent of wind direction. However, the airflow through these vents is over the attic floor, over or possibly into the attic floor insulation. Combining these vents with gable-end louvered vents does not chnage the air flow pattern: the soffit vents do no exhaust through the gable-end louvered vents.Gable-end louvered vents'air flow pattern is also over the attic floor, over, and possible into, the insulaltion. There is no moisture or heat removal in the upper parts of the attic with soffiit or gable-end louvered vents.AVOID drip-edge vents. See page 613 of my book on what is wrong with these vents. The ONLY drip-edge vent to use is the ComboVent. See page 604 of my book for an analysis of what is wrong with turbine vents.The first line of defense against ice dams begins in the basement or crawlspace. Whether you vent or do not vent, seal all openings in the basement ceiling. Do the same thing in the attic floor. Glad to see Buz's qualifier. Note too that not all combinations of ridge/soffit vents work. Where in the soffit the soffit vents are located is crucial. Hope this helps. GeneL.
*Thanks for all the input! I knew this was a rather touchy subjuct, but alas I forgot to add that the house has gable vents, and most likely will use a power fan on the vent on the leeward side gable vent. Gable vents alone seem to be typical in this area, but not too many homes have soffits. I'm thinking that soffit vents with baffles into the attic are going to be my best bet, but I would still like to hear some other pros and cons from those who do it for a living. Thanks.
*Good post to Buzz...at least in my case.While laying in bed one morning as the sun was starting to warm the roof of my new home I heard this slight dripping noise coming from the attic . When I investigated I saw that the underside of my roof was covered with condensation.I had soffit,gable and ridge venting but that evedently wasn't enough.To make a long story short I installed several square roof vents which immediatly cleared up my condensation problem.Dosen't the square ft. area of the attic figure in?Also it has been my experience that soffit and ridge venting seem to work 'hand in hand 'to create a 'draw ' to cause air flow ie. heat rises.
*Wedgehead. Power venting an attic may lower the attic temperature by 20 or 30 degrees. If the attic floor--the ceiling below the attic--is leaky, the power fan will cool off the heat below by sucking it through the leaky attic floor. But the penalty is it also will suck out the heat below in wintertime. The 20 or 30 degtree lower attic temperature has the penalty of a higher electric bill. Lowering the attic termperature has little or n effect on the house's air conditioning load.Beefing up the attic insulation with cellulose is a more effective and less costly way to reduce the heat escaping into the rooms below.Jerry. The combination of attic ventilation devices you have is self-defeating. The gable-end louvered vents short circuit the ridge vents: the gable-end louvered vents are so close to the ridge vents that the ridge vents take the air from the gable-end louvered vents not from the soffit vents.Not all combinations of ridge/soffit vents work. Again, see the chapter on Attic Ventilation in my book, _Complete_Building_Construction_ 4th Edition. GeneL
*Gentlemen - gentlemen - please - what is the point of ventilation? Is there more than one reason? Possibly! If exhausting water vapor is the reason to vent, then as it is rising - we want it to continue to rise - right on out of the house. If those airborne water vapors are to continue to rise, then they require a "vent" just like in the drain waste system of a house (or - ever try to pour gas out of a gas can with the vent closed? - same principal). With out soffit vents the rising vapors are creating a vacuum effect. I really don't care where the air from my soffit vents go - as long as that "venting" allows the exhaust of the water vapor.Gene - I'm not sure why I should care about the airflow patterns in an attic - all I know to care about is exhausting water vapor.(period!)
*What Gene said is true, some combinations of vents are worse than useless, they short circuit . It like puting a Supply Register right next to a return register in a heating/cooling ducted system. The air follows the path of least resistance.If you watch some of the smoke test demonstrations that have been done , yu can get a good idea of what is going on.If you have Gable end vents, consider getting rid of them. The only thing they're , nah actually there are a couple things they're bad for:1: they are very attractive to squirrels and raccoons, the squirrels will gnaw them and enlarge the opening to get in, and the raccoons will rip the slats off and get in.2: fine snow and the right wind condtions will build drifts in your attic, I've shoveled as much as two feet of snow in a cape.3: They can set up air movement that flows straight from one gable end to the other, or if there are ridge vents, the air will blow in the gable vent and out the ridge vent, and the warm , moist air laying on top of the ceiling area will just sit there.4: The wasps love 'em ...... and the painters hate 'em.Get a copy of Gene's book, and tell me if I should read it, or get a copy of Shingle Vent II's video and see some of these smoke tests for yourself.b I love it when a plan comes together !
*Gene,Am I correct in assuming that if the basement is part of the envelope (and used as living space) then there is no reason to seal the ceiling?Jerry (not Hill)
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Joseph FuscoView Image© 1999."Whenever, therefore, people are deceived and form opinions wide of the truth, it is clear that the error has slid into their minds through the medium of certain resemblance's to that truth." Socrates
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Here is an article on the subject, call it opinion 1001. http://www.fpl.fs.fed.us/documnts/pdf1999/tenwo99a.pdf
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Another very good reason to vent an attic area is to prolong the life of the shingles.An experienced eye can spot a home without adequit ventilation.The excessive heat buildup literally 'bakes' the shingles causing them to curl up and eventially fail.I've seen too many 25yr. shingles that had to be replaced after 7-10 years due to this very reason.Stick your head up into your attic on hot July-August afternoon and you will begin to understand why venting is important.
*Do I understand correctly that gable and ridge vents together are counter-productive? We have a hip roof with what some call a dutch gable in the center. There are ridge vents along the hips, gable vents in the gable. And soffit vents in the soffits. Should we remove the gable vents? I've wondered about the snow problem -- we don't get much, but it can blow HARD when we get it, same when it rains. And one gable faces north, whence cometh our biggest storms. Suggestions? (I realize I'm butting in on you, wedgehead....sorry!) Tina
*Tina - my experience says if you have ridge and gable end vents "only" - then there are probably ventilation problems. You said you have soffit vents as well - so I would think you have adequate ventilation. In my part of the country (the oregon coast) we don't worry about snow conditions - so you may want some local opinion on the snow situation.
*Once again, Thanks for the help. You folks on this site have been more help on this house than you will ever know. You really got me thinking about this as a serious matter. Since the roof is already on, and gable vents in and trimmed out, etc., I'm kind of stuck as far as ridge vents go. I've asked a few friends in the trades here locally, and gotten everything from "I wouldn't do soffits without venting them", to "your overhangs are so small I wouldn't even vent them into the attic." So I guess I'm still in a quandry, but choosing to err on the side of caution, and run vents in the soffits, with 3 to 4 foot lengths of ABS pipe bored thru my frieze blocks for venting to the attic. At this point it seems like the best fix I can see. Any flaws in this logic?
*Ditto wedgehead's comments!Buz -- thanks for input. We're going to cover the gable vents from inside with easily removable boards, then see how soffit vents and ridge vents work out. If we need more ventilation, we can open up the gable vents.
*wedgehead - wish I could see an elevation or section drawing of what you intend with 3 - 4 foot sections of ABS. I really don't have a clue as to the need for sections of pipe. If the eaves are closed (covered) then you have a soffit. If they are open you have exposed eaves and bird blocks. Either way it's only a matter of letting air in to the attic space from between each rafter/joist bay. So a soffit would have some sort of screened hole as would the bird block. All there is to it. Make sure your insulation doesn't block the air space just above where your ceiling joist bear on the outside wall. Some times the insulation requires a baffle to hold it down a bit to allow air passage at the underside of the roof deck.
*Buz: The sections of pipe are something I have seen done to make a clean simple baffle to make sure you don't block off the airflow with insulation. They are run through a hole in the bird blocks into the attic and suspended in the rafter bay above the blown-in insulation. The home I saw had this done about every 4th or 5th rafter bay. It looks to be pretty simple and efficient. Removing the blocks is frowned on by the inspectors, as they are needed for shear transfer.Hope this clarifies what I meant. I don't have a way to attach a drawing, so I'm pretty much stuck with my bad english and poor typing. Thanks.
*Wedgehead:Another alternative is Styrofoam baffles that are made for this purpose. They are cheap and easy to install with a stapler. Here is an example of one type that I have used.
*wedgehead - your "bad" english is pretty clear - I see clearly the intention for the ABS - can't say it isn't a good idea - sounds fool proof. The next message refers to baffles I am used to - but actually kind of like the idea of the ABS - might have to try it sometime.
*buz and wedgehead. I strongly urge you to read SOFFIT VENTS on pages 610-612 in my book _Complete_Building_Construction_4th Edition published by Macmillan.The insertion of ABD piping in every 3rd or 4th hole in the bird blocks does not provide adequate soffit ventilation. I have personally seen the destruction of roofs and ceilings in a 52 house subdivision. The ridge vents, with one exception, were fully functional. The pegboard soffit vents were less than 5-inches wide and had a net free venting area (NFVA)of 0.75 sq. in before being painted. The painting , winbd angle, and turbulence around the soffit vent holes further reduced the soffit vent NFVA to ZERO. An emergency justarose. Will finish later. GeneL.
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Gene:
Is it possible to buy your book from you? Who knows, maybe you can make a little money, and I, we, uh could save a little?
Curious and in this case cheap,
Mad Dog
PS email me if you're uncomfortable answering here. Thanks.
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Check out http://www.buildingscience.com site for an interesting take on the subject. What they propose makes sense but is unconventional in most markets. Hope this helps.
*Jerry. The sealing of the basement ceiling must be done regardless of what the basement is used for. Forty percent of the moisture in ahouse originates in the basement. But because of the leaky basement ceiling this moisture ends up in the attic rather than in the house.Buz. The air flow patterns of various attic ventilation devices tells you just how effective these devices are in removing moisture. If you know that the air flow pattern of soffit vents is over the attic floor then you know that no heat or moisture is removed in the space above the attic floor. The same is true--as I noted in an esrlier post here-with gable-end louvered vnets. Indeed, gable-end louvered vents effectively stop working when the wind is perpendicular to the ridge.Combining gable-end louvered vents with soffit vents does not add up to more air movement in the attic. Th e air streams doe not combine, but work independent of each other and ergo, do not constitute a system.Just adding soffit vents is a mistake. For examplke a single louvered soffit vents can be installed in tow ways, one of which is wrong. According the testing done by H.C. Hinrichs(1960) individual soffit vents will not produce the same protection as continuous soffit vents even though the same NFVA is provided. He also found that where in the soffit the vents are located matters. He also founbd that there is little possibility of damaging infiltration in the soffit area if the openings are adjacent to the fascia board and a minimum of 8 -inches from the side wall of the house. Airily yours, GeneL.
*Mad Dog. I do not have a pile of my books in my library. When the book was published the publisher gave me about a dozen copies . I have two left. Perhaps my posts here may be of some help. Sorry I can't be more helpful. GeneL.
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I'm soffiting the overhangs on my new home, and would prefer to not have vents in the soffits. I will vent them into the attic, but leave the exterior sealed. House is in a pretty dry california climate, 4000 ft. elevation with occasional snow and dry CA. summers.
Searched the archives to no avail. Hope you good folks can help me out on this one.
*Wedgehead:There are two reasons to vent soffets: (1) To cool the roof in the winter, so snow does not melt and form ice dams; and (2) To ventilate the roof in the summer, which may prolong the shingles.With only slight snow, ice dams are probably not an issue for you. At 4,000 feet (sounds like Sierra foothills) you'll still get some heat, so venting could be beneficial for both cooling the home without air conditioning and to cool off the shingles.Where is your top insulation? In the floor joists or on the roof rafters? I assume that the attic is not in the home's thermal layer, and that the insulation is in the joists. If that is the case, you attic will get fairly hot, and there may be some benefit to venting.If you don't like soffet vents, you can slap in a couple wind turbins (they do look terrible), some gable louvers (fairly inefficient) or some thermostatically controlled power vents on the back side of you roof (I like those the best). Bear in mind that the power vents run off electricity and on hot August nights will do wonders for cooling off the home (if air conditioned, will suck out cooled air though) but will cost money to run. I have not seen any studies on whether attic vents in temperate climates are actually prolong roof life, although most shingle companies require some form of venting for their warranty. Also bear in mind that roofing warranties are fairly worthless, since 80% of the cost is labor, not their stupid shingles.Bottom line? If the home is air conditioned, I wouldn't vent, except using passive systems such as louvers or simple vent stacks. If it is not air conditioned, I would use a power vent.This subject is highly controversial, and there will be a number of different opinions on the matter.
*Just curious. Assumed soffits had to be vented. We have a metal roof with vented soffits AND gable vents. Our climate can get very cold (down to -20 on occasion) with snow but even coldest days warm up significantly, if not above freezing, then close. Summers are gentle, highs in 80s. Very dry year round, even during "rainy season" in summertime (max annual precip is about 14 inches). Is all that venting on our roof/soffits redundent? If we do any future building, with similar materials, should we vent?
*My house is super insulated. All the houses we've built since '76 have been vented. All since 1980 have had soffit vents and ridge vents.Our favorite combination is perforated vinyl soffit (no maintenance, good looking) and Shingle Vent II shingle-over ridge vent.If you're thinking of power vent , check out the solar powered Fan-attic at:http://www.fan-attic.com/The controversy over vent / no vent is not as easy as it sounds. The ones who espouse "no vent " have developed a whole different system for dealing with the problems of moisture and temperature. So, if you choose not to vent , you should find out what MENU you are going to follow. It's not like you can just leave the vents out, you do have to follow a strategy, or pay the consequences.IMHO
*If your main reason to not vent is that you don't like the way the soffit vents look, I have to say that's not a good enough reason. They're hardly noticeable, so common they're standard, and no one really ever looks up there or cares except tradespeople, from what I can guess. But you may have other reasons. I like the advice of Scooter and Mike here. If you choose to not vent the house, you'll have to follow a rigid system for this, as Mike said, follow a menu. Check the archives if that is the case, there is a fair amount of discussion on the +,- of this argument.MD
*As others said, vent/no vent is a controversial issue, however before you decide not to vent, check your building code or better still, talk to local code enforcement officials - unless you have no need (requirement) to pass a building inspection.Although it seems like an inherently bad idea, there is 1 or more companies out there that make vented drip-edge which may be an alternative to soffit vent.If your reason for not venting is purely aesthetics, you may consider some of the newer soffit material in which the vents are nearly invisible. Personal experience tells me that although these new soffit materials look very good, the quantity of venting they supply are, for many applications, marginal. Here is a URL for one of the products that I am referring to. I have used this one and it looks great. The product is made by Certainteed, but their web server seemed to be down.Also, here is a URL for a PDF file entitled " Importance of Fully Vented Soffit", that I ran across when looking for the above URL. It may present slanted info - but, hey! It's still info.On the other hand, if you have *no* moist air migrating from the living space into the attic, and no building inspector issue, don't vent.
*If the look of soffit vents bother you, try a vent concealed behind a trim boardat the wall at the intersection of the soffit. It can be stepped back from the wall 1-2", continous around the house. Just an Idea. Bill Swales