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Old 01-07-2009, 09:05 PM   #31
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


You can't. They spent a good part of the early 60's putting plastic everywhere when they thought electricity was going to be cheap. The power companies recommended a total encapsulation and would give you a free water heater if you installed electric heat and insulated their way.
In New England, where this occurred, they then spent the next few years actually cutting out the attic plastic vapor barrier and installing thicker insulation, due to the moisture build up and dampness created.
People who had the moisture barrier were running the temps in their homes over 74 degrees or higher to burn off the moisture before they discovered the problem.

Some solar energy people resurrected the idea again in the 70's and 80's with no idea what they were doing.

In remodeling I have been repairing the wall base shoe on some homes that is totally blackened from condensation in walls. I suspect plastic is actually just as good at containing moisture in walls as it is at keeping it out. I am pretty sure plastic sheets don't know what side the moisture is suppose to be on.
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Old 01-07-2009, 09:33 PM   #32
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


I would just like to say that the link that I posted, is to the Central Mortgage and Housing Corporation, owned and operated by the Government of Canada. Their recommendations will be used to formulate future building codes! The horse's mouth, so to speak! Its my understanding, that their research has shown that venting has little or no benefit for roof longevity! However, I just had a new roof installed, and paid for additional venting to be installed in both the soffits and at the ridge! http://www.cmhc-schl.gc.ca/en/co/mah...gemare_001.cfm

Last edited by Wildie; 01-07-2009 at 09:35 PM.
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Old 01-07-2009, 09:49 PM   #33
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


Venting barely affects the temperature in roofing materials so that is true. But moister causes rot and mold in the framing of a structure and that venting addresses.

Maybe in Canada the moisture content from the ground is different. New England is very damp as the ground water is prevalent.

Arizona would be wholly different, so advice or knowledge would apply differently there also.
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Old 01-08-2009, 06:20 AM   #34
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


I understand the debate Barrier versus none. I was in a new show home attic last week, with plenty of blown insulation R40 I'm sure. There was condensation above the barrier when I reached down to pick up my flashlight. It was about -3 that day. So what happens with the condensation with no barrier? Is it supposed to suck into the ceiling behind the paint and cause no damage.?????
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Old 01-08-2009, 07:43 AM   #35
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


So if I understand you correctly you have plastic film over the insulation in your attic that has puddles on it?

The theory is condensation vapors from your house atmosphere mainly rise with the heated air, warm air can support more moisture than cold air, and when it reaches colder air that can not support that moisture it drops off.

If the attic isn't vented properly the moisture hangs on things, rafters, sheathing and insulation. Obviously if you have moisture being contained by a barrier, or not getting out the vented attic, the moisture drops off and works its way back into the environment in what ever way it wishes, caused by a condition barrier or physical barrier.

If you have moisture on top of the barrier in an attic, your attic is saving moisture some how. I would wonder if it was because of the barrier, as insulation doesn't prevent moisture passage but plastic does.

Very cold air may be the barrier too and the plastic is catching the moisture as it falls out of the attic atmosphere. A good debate I am sure but moisture prevention is done in the basement and limited in the living environment and the rest is exhausted as best as possible from the attic.

At least that is the theory. Conditions in each environment create different solutions and problems, so often times there will be a case of reverse logic that some times has a positive affect.

An attic is not a dehumidifier so attempts to alleviate an over abundance of acquired moisture from below creates its share of problems. The best bet is always to prevent all gained moisture other than living condition moisture, such as breathing cooking and water usage, below the cellar slab. Then the only moisture to remove is minimal. If there is no plastic under the foundation, and you live on earth, there is a great likely hood that your spot upon it is evaporating moisture continuously into your habitat that you are trying to pass through an attic vent with little condition adjustable abilities.

I can only say that if what you are doing keeps the moisture out of the insulation and leaves it in a place that the attic can deal with it, in a way that doesn't harm the structure, then what you are doing may as well be right for your conditions.
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Old 01-08-2009, 10:53 AM   #36
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


Baron, the condensation I found was above the barrier, below the blown insulation. No forst on the underside of the roof.
Wildie, it is Canada Mortgage and Housing Corp and CMHC doesn't indicate which way we're headed. They are a mortgage loan insurance provider....
Ontario building code requires a vapour barrier, generally.... 6 mil, sealed with acoustical sealant or red contractor tape on all insulated exterior walls, ceilings, etc. installed on the warm side of insulation. New construction must pass inspection for insulation and barrier before drywalling.There are exceptions where spray foams, etc are being used.
We are also building super energy efficient homes under the Energy Star and R2000 ratings/guidelines. These utilize a much tighter ENVELOPE approach and promote specific material requirements for air seal, etc...
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Old 01-08-2009, 11:35 AM   #37
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


Quote:
Originally Posted by earthad1 View Post
Hmmm, interesting... Could this be why my soffit vents may be sealed off? Because I have 2 gable vents???
It quite likely! Its akin to having a bucket with a hole in the side,only upside down.
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Old 01-08-2009, 11:44 AM   #38
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


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Originally Posted by Chemist1961 View Post
Baron, the condensation I found was above the barrier, below the blown insulation. No forst on the underside of the roof.
Wildie, it is Canada Mortgage and Housing Corp and CMHC doesn't indicate which way we're headed. They are a mortgage loan insurance provider....
Ontario building code requires a vapour barrier, generally.... 6 mil, sealed with acoustical sealant or red contractor tape on all insulated exterior walls, ceilings, etc. installed on the warm side of insulation. New construction must pass inspection for insulation and barrier before drywalling.There are exceptions where spray foams, etc are being used.
We are also building super energy efficient homes under the Energy Star and R2000 ratings/guidelines. These utilize a much tighter ENVELOPE approach and promote specific material requirements for air seal, etc...
I stand corrected! I guess that I have revealed something of my antiquity. If my memory serves correctly ( and it can be doubtful at times) it used to named Central M.....
The sneaky bu******rs changed the name without telling me! [grin] I know it was renamed, as I have one of their books, with the old name on it!

Canada Mortgage and Housing Corporation (CMHC) is Canada's national housing agency. We are committed to helping Canadians access a wide choice of quality, affordable homes, while making vibrant, healthy communities and cities a reality across the country. CMHC works to enhance Canada's housing finance options, assist Canadians who cannot afford housing in the private market, improve building standards and housing construction, and provide policymakers with the information and analysis they need to sustain a vibrant housing market in Canada.

Last edited by Wildie; 01-08-2009 at 11:49 AM.
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Old 01-08-2009, 12:17 PM   #39
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


Wildie here's what I know about CMHC from personal experience

CMHC does provide insurance for our (non private) banks on higher ratio loans beyond 75%. In doing so they also may inpsect a home internally to insure it's value for the lender. My first purchase was approved with a drive by as I had just over 22% for a larger home.
They didn't come in and discuss my aluminium wiring so what kind of information and analysis is that?
Anyway I don't think I would be reading their old books for qualified informed info... They did not come in and locate the 42" missing from my sill plate adjoining my garage, nor the 12' gap by 8" of missing plywood on my garage wall in the attic opening into my formerly drafty kitchen bulkhead, so like any DYI fanatic, I stumbled across them myself. Granted this was a quality home and codes were different when it was built as were inspections and its in an upscale neighbourhood ......so I was a VERY safe loan. But does this sound like someone with building industry knowledge?
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Old 01-08-2009, 01:41 PM   #40
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


We know buildings have to be built different in different climate zones. Some places have different problems with cold and moisture than other regions. Which ever problem is your primary concern drives how you build your house.

My current understanding of the basic concept is you build your house so the living space is a tight controlled space. You attempt to control air coming into and leaving this space as much as possible and you attempt to control the temperature in this space as well.

If you had a ceiling of drywall, then plastic vapor barrier, then studs, then R-40 insulation then open space then roof rafters then a vented roof... and you found water on the attic side of the vapor barrier then it must be dripping down into that space, it can't condense on the vapor barrier because the barrier should be the same temperature as the room below it. If the moisture was on the ceiling side of the vapor barrier then you could have water problems inside your room, that would indicate that you are venting your living space adequately.

This system seems to work best in Very Cold and Cold climates. I'm not sure the vapor barrier is as useful when you get into the drier western zones of those climates. The vapor barrier is very helpful in containing air and keeping warm air from leaving through cracks.

http://www.buildingscience.com/searc...=vapor+barrier

all kinds of good stuff.
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Old 01-08-2009, 01:46 PM   #41
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


You're right, thats from right here where I live litterlaly 2 blocks from my house. Saw this before but lost the link.
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Old 01-08-2009, 04:03 PM   #42
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


Quote:
Originally Posted by Chemist1961 View Post
Wildie here's what I know about CMHC from personal experience

CMHC does provide insurance for our (non private) banks on higher ratio loans beyond 75%. In doing so they also may inpsect a home internally to insure it's value for the lender. My first purchase was approved with a drive by as I had just over 22% for a larger home.
They didn't come in and discuss my aluminium wiring so what kind of information and analysis is that?
Anyway I don't think I would be reading their old books for qualified informed info... They did not come in and locate the 42" missing from my sill plate adjoining my garage, nor the 12' gap by 8" of missing plywood on my garage wall in the attic opening into my formerly drafty kitchen bulkhead, so like any DYI fanatic, I stumbled across them myself. Granted this was a quality home and codes were different when it was built as were inspections and its in an upscale neighbourhood ......so I was a VERY safe loan. But does this sound like someone with building industry knowledge?
Some how, I'm given the impression that you think that I espouse CMHC. I would direct your attention to where I stated that I personally, chose not to follow their direction, and had ventilation installed according to conventional wisdom! My intent was to give the original poster a web page, where he could gain some knowledge about his problem and nothing more! Somethings change with time and some things do not! I'm quite aware of all the wonderful advances that have be made in home construction and how its considered best to have a closed environment. Never the less, its all not coming up roses! We now have air quality problems, that we didn't have when we lived in drafty old house's with inefficient octupus gravity furnaces etc. There's a real possibility that our families health has been compromised, in the name of saving a couple of bucks! As witnessed by the OP's problem in the attic, which has a real potential to turn into a mold problem that could be bad for his health! Have we advanced?
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Old 01-08-2009, 04:28 PM   #43
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


I have seen three generations bring changes into home climate, trying to convince people to create a controlled environment and use electric devises to eradicate moisture and move air that would have "naturally" flowed through the house. If it were built in consideration to humans and not to some ecological fantasy and religious desire to create atonement to a cause by code enforcement, i would perhaps be less cynical.

However I have seen no evidence in New England in 30 years that plastic enveloping a house can work without a huge amount of electric devices running to control and otherwise natural process.

Biological substances and spores need moisture and stale air to microscopically attack your home which is made of natural things.

I know of a Doctor who developed a nasal conditioned gained from his own habit of storing fire wood in his damp cellar. His condition shortened his life and was preventable with ventilation or not storing wood in his cellar.

I meet many people who have developed asthmatic conditions living in musty homes that have been built to code. I am not impressed with this latest push to force bubble living onto an unsuspecting public.

Stagnating water and damp conditions are products of the plastic envelope construction that has a higher cost to maintain due to the need to dehumidify are circulate air with exhaust fans. Why is money spent to dehumidify or expel more saintly then money spent for heat?

Again this is the third generational attempt I have been witness to, where marketers have tried forcing climate control construction that relies on electric devises to regulate interior living habitats, with poor health results as an acceptable sacrifice, all in the name of a political movement and not practical sense.

It didn't work positively in the 60's, again in the 80's and now we are seeing it mandated by code, with no consideration for its affects on health, building materials or long term value, and ignorant of its poor track record to boot.
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Old 01-09-2009, 05:35 AM   #44
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Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation


Wildie, I am sorry, didin't mean for my comments to offend you. They were meant to be directed toward the website. Let's just say, I think CMHC overstates their purpose and are not a resource most people I know would be looking to beyond insurance.
Although I too have sealed my attic holes and wiring etc and patched my vapour barrior I think Baron makes some excellent points. It would seem we should be building our homes with a Goretex like material as an air barrier. One that allows moisture to exit one way but stops draft and moisture from enterring? Is that correct? Traditionally our barriers have been on the warm side but a breathable one placed inside could trap moisture within the wall cavity so how would that be resolved?
With the little I know about Tyvek and newer building wraps I think the industry may be headed that way however that does not solve the issue of fresh air venting in naturally in an otherwise airtight space. And is there one good material for the variety of conditions we see across North America.
Has anyone got any feed back on how the Europeans handle this in their new home construction?
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Old 01-09-2009, 04:37 PM   #45
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Sorry to hear about your less than satisfactory experience with CMHC! Perhaps your deficiencies should have been picked up by your home inspector, as CMHC's interest is more financially focused! Anyway, nuff said, as I suspect that we are in danger of hijacking this post. Getting back to vapor barriers! The whole idea is to prevent warm, moisture laden air from contacting cool surfaces, where the moisture will condense and cause damage! Its basically a simple concept, that doesn't require new technology or concepts. Our present methods are functioning well, in millions of homes!
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