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Old 02-14-2010, 08:39 AM   #16
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Damn Ice dam -damn!


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Originally Posted by Bob Mariani View Post
But a poor mans test to find air leaks is to look at your roof a few days after a good snow. Houses where all the snow is still there are sealed correctly. houses with no snow have not insulation. But the majority of the houses will have areas of melted snow.... these areas are exactly where the air sealing is not done correctly.
Areas of melted snow depend greatly on position of house relative to available sunlight.

The south side of the house will most likely see more melting vice the north side.

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Old 02-14-2010, 09:19 AM   #17
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Damn Ice dam -damn!


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Areas of melted snow depend greatly on position of house relative to available sunlight.

The south side of the house will most likely see more melting vice the north side.
Ya, but "science" only calculates numbers and theories to make a good assumption, until it is debunked or proven.

Haven't seen many science experiments conducted in the real world. Often it is in a controlled environment.

I'm interested to read the responses here.
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Old 02-14-2010, 11:29 AM   #18
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Damn Ice dam -damn!


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Ya, but "science" only calculates numbers and theories to make a good assumption, until it is debunked or proven.

Haven't seen many science experiments conducted in the real world. Often it is in a controlled environment.

I'm interested to read the responses here.
your response to this is wrong. Actual testing is done and done often now. Almost every government is paying big bucks to find out how to make houses more energy efficient. But because contractors do not understand the science and thus are afraid to change their evil ways even new homes need to be retro-fitted to make them tight enough but still be safe for humans. As such rebates for fixing these problems is only available to owners using accredited building performance analysts. look at the silly response to some of these issues.. These are far less useful then the science you so quickly disregard due to your lack of understanding. Too much is online that gives opinions and not real solutions. But even on the good sites the old articles are still listed and some confusion exists since more testing has refined the best solution. so I will continue to follow the science and do it right. The government offers 18 billion for us to do so. (only if done by BPI auditors) New York and many other states now are adding to this program. And all require the same accreditation. Maybe the too see that understanding how the building interacts with humans, weather and moisture flow has some value in doing things right.
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Old 02-14-2010, 04:27 PM   #19
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Damn Ice dam -damn!


Didn't mean any offense Bob.

I purposely watch for your posts for info. Take that however you like. It should be a compliment.

Just stating that many things that are considered "scientific" are debunked or proven every day. Global warming to be one of the big ones.

Codes are often backed up by supposed scientific data, but I have seen the codes change many times in the last 15 years. I even see house codes that totally conflict each other around the country. Walls and moisture is the biggest.

I have seen what the government pushes, and sometimes it really does create more problems for homeowners. Just look at the posts here........
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Old 02-14-2010, 05:05 PM   #20
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Damn Ice dam -damn!


all of what you say is correct. But we need the tests and the science to make things better. The code changes when they feel that things are proven to be so and then accept the changes. These changes take longer than we want them too. A good example.... we always had to cross vent crawlspaces. No with new rules backed by science and testing we have to seal crawlspaces. And poly as you mentioned... best to never use it unless you are in the very cold climate areas or under slabs. Another issue we have to deal with is codes that are not updated. But I have submitted info to building departments showing them why I need it the way I do it and have had much success in changing their minds with few exceptions.

And thanks for the compliment. Did not take your comments personally, just trying to explain that much in the industry still needs to be fixed and all contractors and DIYer need to be educated more.
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Old 02-14-2010, 08:14 PM   #21
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Damn Ice dam -damn!


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just trying to explain that much in the industry still needs to be fixed and all contractors and DIYer need to be educated more.
I can't agree more.

It's funny, I remember the energy audits in the early 80's. The "government" had people running around adding styrofoam inserts behind the plates of our light switches and outlets. Money, time, and research well spent.
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Old 02-15-2010, 07:36 AM   #22
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yeah... I was an energy auditor then. But now the science has shown new things that are more valuable to fix. And things like windows and plate insulation is not longer on the list.
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Old 02-15-2010, 11:59 AM   #23
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Damn Ice dam -damn!


Foam baffles are an inferior product- they burn toxic smoke, vent only 18.7sq.in. per -24 bay, snag and rip on the nail points in the roof deck., need an additional Windblocker to protect the insulation edge from wind washing: http://www.adoproducts.com/duro.html http://www.adoproducts.com/wind.html
Even the O.C raft-R-mate vents 22.3sq.in. (17% more): http://www.owenscorning.com/around/v...s/VentSure.pdf
Id use the H.Ds plastic one that self-extinguishes in -5 seconds, with 25.3sq.in. (35% more): http://www.bergerbuildingproducts.co...sAccuvent.html

The basics: http://bct.nrc.umass.edu/index.php/p...ting-ice-dams/

Start with your own visual diagnosis: http://www.homeenergy.org/consumerinfo/roofs.php

Be safe, Gary
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Old 02-15-2010, 12:21 PM   #24
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Damn Ice dam -damn!


Central Mortgage and Housing in Canada has researched this problem thoroughly! Here's a link to a good article about this problem.

http://www.cmhc-schl.gc.ca/en/co/mah...gemare_001.cfm

A quote from this article! "If you have properly sealed the attic you should not need more attic ventilation. Attic ventilation is overrated. In winter, the cold outside air cannot hold much humidity or carry moisture away from the attic. In summer, attic temperatures are more affected by the sun and shingle colour than by the amount of ventilation"

Last edited by Wildie; 02-15-2010 at 12:26 PM. Reason: Additional info!
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Old 02-16-2010, 02:25 PM   #25
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Damn Ice dam -damn!


Wilde, That quote you entered pretty much goes against everything any other orginizational body is saying including HUD and the FHA in addition to ASHRE, IBC, as well as the University of IL and most shingle manufacturers.

With proper ventilation, the color of the shingles doesn't matter much to the interior temprature of the attic. A properly ventilated attic will evacuate that difference. However yes the surface temprature from a white to black shingle could easily be 40 degrees F. But surface temprature doesn't necessarily equal interior temprature.



GBR, In regards to "burning toxic gas", if you are worrying about that, you have bigger problems than your attic ventilation.
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Sometimes the savings that comes from doing it yourself can be blown away with one mistake.

The information found in this post is not to be considered legal advice. All information should be considered relative, not specific. Never attempt any repairs you are not comfortable with. Always maintain safety! The author of this post takes no responsibility for any losses that occur. Use at your own risk.
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Old 02-16-2010, 04:09 PM   #26
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Damn Ice dam -damn!


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Wilde, That quote you entered pretty much goes against everything any other orginizational body is saying including HUD and the FHA in addition to ASHRE, IBC, as well as the University of IL and most shingle manufacturers.

With proper ventilation, the color of the shingles doesn't matter much to the interior temprature of the attic. A properly ventilated attic will evacuate that difference. However yes the surface temprature from a white to black shingle could easily be 40 degrees F. But surface temprature doesn't necessarily equal interior temprature.



GBR, In regards to "burning toxic gas", if you are worrying about that, you have bigger problems than your attic ventilation.
What was your main reason for going with blown fiberglass vice cellulose?

Do you buy into the claim that the R value of fiberglass drops by 50% as temps drop below freezing?

What R value do you have in your attic?
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Old 02-16-2010, 09:02 PM   #27
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Damn Ice dam -damn!


Simpson and McPherson25 found
that white roofs were up to 36F (20C)
cooler than gray roofs, and up to 54F
(30C) cooler than brown roofs. Cash and
Lyon26 have recently shown through
computer modeling that shingle temperature
is more strongly a function of geographic
location, the direction a roof
faces, and surface color than ventilation.
Venting cools shingles, but the cooling
effect is not strong.


By 1967, the “cold roof ” concept had been introduced, but it was based on a combination
of measures. cathedral ceilings are presented in Tobiasson et al.22 for various roof slopes, airway heights and insulation levels. These calculations do not consider the effect of wind, air leakage up through
the ceiling or heat lost up through the snow. They concluded that the need for ventilation is related to the
amount of snow to be expected in the area and the amount of insulation in the ceiling. In Philadelphia,
Washington, D.C. and Chicago, roofs with at least R20 (3.5 m2kW) need not be ventilated. In Madison,
Heat loss into attics from air leaks, ducts or flues can lead to ice
dams, even when the attic is vented.
Baker15 stated that for a permanent solution to ice dams, “consideration must be given to more adequate roof or ceiling insulation, ventilation of air spaces above the insulation, and moderation of inside temperatures.” He observed that on insulated buildings, ice dams form at outdoor temperatures above 15F (–9C). Latta16 recognized the importance of air leaks and recommended attic ventilation, but only after “blocking all passages by which warm air can leak into the space below the roof.” Wolfert and Hinrichs17 only briefly mentioned ice dam minimization in their manual on attic ventilation.
Grange and Hendricks18 authored the first publication that fully focused on ice dams. They emphasized a combination of attic vents at the eaves and ridge and minimization of all attic heat sources. The importance of attic heat sources strongly emerged in a recent study of 33 houses in Ottawa, ON, Canada.19
All 16 houses with ice dams had interior chimneys and their Wis., Boston, and Sioux Falls, Idaho, the minimum amount of insulation increases to R-30 (5.3 m2kW), and in Minneapolis and Portland, Maine, it increases to R-40 (7.0 m2kW). In Marquette, Mich., and Bangor, Maine, all roofs, no matter how
well insulated, need ventilation to avoid ice dam problems. From: http://www.fpl.fs.fed.us/documnts/pdf2002/rose02a.pdf

"GBR, In regards to "burning toxic gas", if you are worrying about that, you have bigger problems than your attic ventilation."----- missed you completely...



30-50% at 60-70* under certain conditions: http://www.osti.gov/bridge/purl.cove...8/webviewable/



Be safe, Gary
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Old 02-16-2010, 10:37 PM   #28
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Damn Ice dam -damn!


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Wilde, That quote you entered pretty much goes against everything any other orginizational body is saying including HUD and the FHA in addition to ASHRE, IBC, as well as the University of IL and most shingle manufacturers.
I wouldn't dispute that it goes against what has been the standard methods!
Makes one wonder how this will end up after the dust has settled!
CMHA is staffed by very crdible scientists and of course financed by the Canadian government.
These guys aren't a bunch of rabble rousin' yahoo's. They are the guy's that are setting Canadian standards for construction!
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Old 02-16-2010, 10:45 PM   #29
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Imagine that......scientific data that contradicts itself from one study to another.......

GBR, your quote is for "cold roof" or "hot roof", which is not ventilated. It's parallel board construction with no venting.
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Old 02-17-2010, 09:02 AM   #30
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Damn Ice dam -damn!


GBR it didn't miss me. Your house is on fire. Get out. Everything's going to burn, stop worrying about your attic ventilation and get out quick. LOL it's not like those baffles would be the ONLY foam in the house, couches, chairs, mattresses... any of which have tons more foam and toxuc gas than foam baffles. I am not disputing your comment, it is totally true, however not worth further discussion so it's sooo far out there. I'd not make a decision on a foam baffle based on my house burning down, if that were the case I'd have them made out of some kind of class A material.

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Sometimes the savings that comes from doing it yourself can be blown away with one mistake.

The information found in this post is not to be considered legal advice. All information should be considered relative, not specific. Never attempt any repairs you are not comfortable with. Always maintain safety! The author of this post takes no responsibility for any losses that occur. Use at your own risk.
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