*
You ask how come we don’t hear more from Bill Rose, Joe Lstiburek and Steve Smulski on the forum. Good question. Andy is right, it’s up to the authors. I check in, maybe once a week and I learn more from the forum that I could possibly contribute-that’s why I mostly listen. I respond when I feel I have some contribution to make, but mostly I keep my peace. Why’s that? There’s laziness and being too busy and traveling too much. There’s the sense that I’d have to write a boring treatise and dampen the lively humor. As an academic, it doesn’t go on the publication and promotion list. There’s the classic researcher’s dilemma of writing for several audiences with competing needs to 1) keep it simple and 2) get it exactly right. There’s the yebbit problem.–“Yebbit, what about ridge and no soffit?”-that makes it easy to enter a discussion but hard to leave one.
I’m also concerned about the “voice” of the site. When someone asks a question and someone else responds “I did it like this; seems to work; client’s happy; watch out for this”, that makes my day. I learn a lot. That’s what I like about the site, that and the irreverence and the humor. What I mind is the occasional patronizing, sometimes with parental sarcasm like somebody just brought the car home late. No builder ever needs to be scolded. Well, one exception-please improve your spelling.
As for venting of steep roofs, I think 80% of the roofs are vented and good, 10% are vented and bad, 9% are unvented and good, and 1% are unvented and bad. Incidentally it’s Mister Bill, not Doctor Bill.
Replies
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© 1999-2000
"More than any time in history mankind faces a crossroads. One path leads to despair and utter hopelessness, the other to total extinction. Let us pray that we have the wisdom to choose correctly."
Woody Allen
*Hey Joe,You finally throw a party and nobody shows up. I'm here for you man.I agree, good article. I also wonder why few if any of the contributors to fhb post here. I thought it was pretty neat when Larry Haun posted a few times, then he was gone. Maybe Andy can put the screws to 'em and make them come around. What do you say Andy?Tom
*New issue?
*I remember at least once when Larry Haun stopped by here and sombody jumped in his s@*t bigtime. Kinda wondered if he got run off. I havn't got the new FHB 7/2000 issue yet.
*I met Joe Lstiburek and spoke to him several times. Admittedly, we are all small potatoes to him. One project he discussed with me was a ski lodge he and his wife Betsy did.It was a ski lodge for some arabian prince built in Aspen CO. It had a 50,000 (no typo - fifty thousand) square foot unvented roof, an entire pub moved from england, etc. etc. I don't even think I've looked at 50,000 sf of roofing in my life.The one issue I have with Smulski's article was his statement: "Otherwise, air flowing from the soffit vent to the rideg vent would have carried this moisture outside as designed."From a purely scientific point of view this is an absolute statement, which cannot be made in this situation. The only thing that would have absolutely stopped the condensation would have been eliminating the moisture source.This may not be his fault actually, I know the editors "fixed" Fred's captions as well. Oh, gee whiz, there's a guy that writes for many magazines and also contributed here.For the record - I am not anti-venting. I just wish the emphasis were placed on proper air sealing. Air sealing has benefits. Venting is used as insurance against construction defects. And there are many instances where venting a roof will not address the intended symptom - for example in the mentioned article, if a recessed light over a tub were under that condensation than venting probably wouldn't have stopped the condensation. The escaping heat and moisture would overpower any venting effect. But air-sealing the light would have stopped it for sure.Then there are the situations where venting adds cost, has deleterious side effects, or plainly adds no value. I think my roof is a good example. 2.7" of polyiso foam, joints sealed with foam, applied over continuous sheathing and dense packed rafter bays. What did the 1/2" furred out airspace above the foam do for me? It added cost. Luckily because the inspector never came I limited the cost implications by not bothering with the soffits and ridge - and whattaya know - no condensation or ice formation this winter - one of our coldest and snowiest ever.Venting is only one way to deal with a problem that takes dozens of different forms. Please just understand this one point - Maybe don't understand it, but just acknowledge that the possibility exists.Incidentally - Joe Lstiburek and others have done over twenty years of research in this field, it has often been quoted by Gene on this thread and usually dismissed by Joe Fusco and the "pro-venting" crowd.-Rob
*I'm very sorry i missed Larry Haun's posts. I've enjoyed his articles for over 10 years now in FH.Any one that would blast him here with out cause is a moron. Since i didn't see the interaction i can only speculate.I will additionally speculate that those tradesman that followed Larry's rough framing would sing his praises.joe d
*Rob,
View Image © 1999-2000"More than any time in history mankind faces a crossroads. One path leads to despair and utter hopelessness, the other to total extinction. Let us pray that we have the wisdom to choose correctly." Woody Allen
*Tommy b,
View Image © 1999-2000"More than any time in history mankind faces a crossroads. One path leads to despair and utter hopelessness, the other to total extinction. Let us pray that we have the wisdom to choose correctly." Woody Allen
*I say that the author's time is their own, but I encourage any of them to post here. I know of several who have, i.e. Larry Haun, Bill Rose, Gary Katz, Fred Lugano, Herrick Kimball and Mike Guertin. There may be others whom I'm forgetting, and I'm certain that many are lurkers. Would you be interested in a formal opportunity to chat with current authors on-line?Andy
*Hi Joe,It was a good article alright. Most of us, who work mostly in commercial, recognize the value of proper ventilation. Hope you're working hard and reaping the benefits,Gabe
*Joe. Smulski's points are well taken. They are of course exactly what Joe Lstiburek has advocated for more than 20 years. I first learned of the rasin screen principle/vented csvity from him in 1980. GeneL
*You ask how come we don't hear more from Bill Rose, Joe Lstiburek and Steve Smulski on the forum. Good question. Andy is right, it's up to the authors. I check in, maybe once a week and I learn more from the forum that I could possibly contribute-that's why I mostly listen. I respond when I feel I have some contribution to make, but mostly I keep my peace. Why's that? There's laziness and being too busy and traveling too much. There's the sense that I'd have to write a boring treatise and dampen the lively humor. As an academic, it doesn't go on the publication and promotion list. There's the classic researcher's dilemma of writing for several audiences with competing needs to 1) keep it simple and 2) get it exactly right. There's the yebbit problem.--"Yebbit, what about ridge and no soffit?"-that makes it easy to enter a discussion but hard to leave one.I'm also concerned about the "voice" of the site. When someone asks a question and someone else responds "I did it like this; seems to work; client's happy; watch out for this", that makes my day. I learn a lot. That's what I like about the site, that and the irreverence and the humor. What I mind is the occasional patronizing, sometimes with parental sarcasm like somebody just brought the car home late. No builder ever needs to be scolded. Well, one exception-please improve your spelling.As for venting of steep roofs, I think 80% of the roofs are vented and good, 10% are vented and bad, 9% are unvented and good, and 1% are unvented and bad. Incidentally it's Mister Bill, not Doctor Bill.
*Oh No! Mister Bill,
View Image © 1999-2000"More than any time in history mankind faces a crossroads. One path leads to despair and utter hopelessness, the other to total extinction. Let us pray that we have the wisdom to choose correctly." Woody Allen
*Gabe,
View Image © 1999-2000"More than any time in history mankind faces a crossroads. One path leads to despair and utter hopelessness, the other to total extinction. Let us pray that we have the wisdom to choose correctly." Woody Allen
*Joe, I didn't mean to signal ou in particular out - sorry. You must be between jobs you have been absent here lately.My point in saying "pro venting" people is that I see these people have come around to the idea of air sealing. They haven't yet made the connection to the need for venting.Take my stupid question to Narenda Varma for example. I know it wasn't you in the thread, but Gabe and others have repeatedly projected a position that unvented roofs will ALWAYS fail. Again, I have issue with the absolution of the need for venting from a purely scientific or statistitian standpoint. The fact is, we know that is simply not the case many homes (mine included) have been around over 100 years without formal venting strategies. The issue of heat and moisture are dealt with very subtelly and effectively in these old structures. The only conspicuous signal is the lack of ridge and soffit vents.I remeber the example I wanted to use last night. Every time someone who wasn't wearing their setabelt dies in a car accident around here there is always some policeman who will say "If they hadbeen wearing their seatbelt they would have lived." A totally bogus agenda ridden line.I have also tried to get people to realize that airflow and radiant heat transfer are entirely unrelated - I am either not trying hard enough or I am a poor teacher. The best I could do in that case is recount how my wife and I went snowmobiling in the Colorado Rockies on a cloud-free sunny 40 degree day. We were wearing shorts and tank tops. Despite our attempts to maintain an average trail speed of 70 mph we did not get cold and we did get sunburned.Roof venting is the same thing. Cold air goes thru, and does not much because the sheathing is heating up anything it sees by a heat transfer mechanism several times more effective than convection.-Rob
*Gabe - you mentioned commercial work.I am designing bulk handling and chemical feed systems now to go in a new building that will have an unpenetrated ceiling made of precast concrete planks and covered with 3" rigid iso board. This roof will benefit none from venting.What really concerns me are these "quasi-commercial" buildings that are wood framed, with large expanses of shingle roof, on slab and all the mechanical systems in the attic - outside conditioned space. Remeber the picture Fred showed us? The airhandler was under 4 feet of fiberglass, the soffits and gables were nearly wide open. Yet the mecahnical systems performed so poorly that they made the attic semi-conditioned space. That roof started out properly vented. When it failed they added more soffit venting. When that failed they added gable vents. You can't vent more!!! Sadly, $1000 applied properly would have fixed the problem and eliminated the need for the venting, or at least the additional venting.-Rob
*Don't misquote me, Rob,I never said that they would always fail.A good teacher must first learn all the facts and only then can he teach what he has learned.Gabe
*If the roofing membrane is on top of the 3" insulation, the membrane will probably fail prematurely and it won't be because of the lack of venting either. This is why we use inverted roofing systems. we protect the membrane from the heat of the sun by covering it with insulation, filter cloth and stone ballast.I don't know what quasi commercial relates to, so I can't comment on it.Gabe
*Rob,
View Image © 1999-2000"More than any time in history mankind faces a crossroads. One path leads to despair and utter hopelessness, the other to total extinction. Let us pray that we have the wisdom to choose correctly." Woody Allen
*My point in the snowmobiling metaphor was that I had damn rapid convection of 40 degree air all around me, but due to the close proximity of the sun my body was always heated to a comfortable temperature.I made the same point to a guy at the ACCA training here. It was the second week of april, mid 30's or 40 degrees outside, but not a cloud in the sky. Frank Vigil was explaining this heat transfer mechanism through the attic to a guy outside during a break. Well the room was so cold my feet were numb and I went outside to stand in the sun, next to the melting snow, to warm my feet up.I followed your link, and I have been to that section before. To be honest I still don't understand why you don't understand that hot plywood radiates heat. That's all the underside of the roof is - hot plywood. Yes, I understand that the sun heats the roof, and that heat conducts through the ply and framing, and the surface of the plywood gets hot and causes convection. I think what you miss is that these same hot surfaces are radiating heat at the ceiling below. This is why in the winter time you can stand next to windows in an 80 degree room and feel cold. The surface temp of the window is 30 or 40 degrees colder than the air and 50 or so degrees colder than your body. If it is apparent at a 50 degree delta T than why wouldn't it be apparent at an 80 or 90 dgree delta T.I guess we'll have to agree to disagree - I don't type properly and my hands and arms are starting to ache constantly. I can't keep up these long posts.-Rob
*I should have been clearer. This was a flat spancrete roof that has lightweight steel trusses and standing seam roof over it.The inverted roof is a damn pain to find leaks in though.-Rob
*Rob,
View Image © 1999-2000"The first step towards vice is to shroud innocent actions in mystery, and whoever likes to conceal something sooner or later has reason to conceal it." Aristotle
*If you know how to build an inverted roof properly, looking for leaks isn't an option.Gabe
*What defines a radiant body? If warm objects are not radiant bodies and do not emit longwave ifra-red radiation, than why bother making low-E coatings?-Rob
*So you are saying that you can guarantee this type of roofing to never leak ever?-Rob
*I can guarantee that it will last longer.Gabe
*Joe et al. If any of you have back issues of the Old New england builder(now JLC) see the May 1986 issue for Bill Rose's article "Vapor Barriers: Putting the Rumors to Rest. Nice picture of him. GeneL.