Attic Insulation

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  #1  
Old 07-28-02, 05:09 PM
dsteece
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Attic Insulation

In my attic i have about 3 inches of cellulose loose filled insulation with no vapor barrior. i live in virginia. i know i need more insulation. was wondering what type would be better to use and if i require a vapor barrior. guess i need a R-38 value. thanks for any help
 
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  #2  
Old 07-28-02, 08:51 PM
R
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Though many contractors mix different types of insulation, it is not advisable to do so. This is because different materials absorb and expel moisture at different rates. You cannot apply a vapor barrier between insulation, it will cause a moisture problem. Several layers of paint on a ceiling qualify as a vapor barrier and cellulose, unlike fiberglass, does not depend on trapped air as much. This along with the low absorbancy rate fiberglass has to moisture makes cellulose a product that has a much lower probability to moisture problems in comparison to fiberglass.

My advice is to either blow in more cellulose or buy bags of it and spread it out yourself. You'll find spreading it out yourself is not that difficult.
 
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Old 07-29-02, 05:30 AM
Zathrus
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What about mixing fiberglass and cellulose blown in insulation? My attic currently has 4" of fiberglass blown in, and I'm planning to up it to 8" this fall.

Is it ok to mix the two together, or should I move the current insulation all into one area and then backfill with new cellulose?
 
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Old 07-29-02, 06:34 AM
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I would recommend stay with the fiberglass. You can use unfaced fiberglass batts to give you the desired height. You will find it easier to install, less expensive and more effective than putting cellulose over the loose fill fiberglass. The weight of the cellulose will have a tendancy to compress the loose fill fiberglass.
 
  #5  
Old 07-29-02, 12:04 PM
rbisys
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Greetings,

Putting more of the same low efficiency (about 10%) material over the top of of low efficiency insulation is a waste of time and money. In fact, depending on how much is already up there it may not save enough energy to pay for its self.

The most efficient way to up grade is to install a radiant barrier (RB) over the existing material. I have seen savings up to 30% and you won't get that with bulk insulation. Surprisingly the amount you have is about maxumin for winter savings.

Go thru "google" and enter "radiant barriers"

For more detailed info regading your project, contact me at "[email protected]"

Thank you for considering my opinion.
 
  #6  
Old 07-30-02, 06:35 AM
Zathrus
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I've put up radiant barriers before, and I've done insulation. I've also done a good bit of research into this. The non-profit conservancy Southface (www.southface.org) as well as the DOE's Oak Ridge Laboratory (www.ornl.gov) contradict your statements regarding insulation efficiency vs radiant barriers.
 
  #7  
Old 07-30-02, 08:17 AM
rbisys
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Greetings,

That's because they didn't know how to install/test properly.
I've been thu it with DOE and others and the answer is the same, we don't have the money to test in installed homes on a comparison bases. As long as they can mickey mouse the process they control the people. What? You don't believe we're being controlled?

Besides the government/ DOE doesn't want to see really energy efficent insulations succeed because that cuts into the 10's of billions of dollars of tax monies the government collects from from a corrupt system. I think my 30 years of new/retrofit field experience trumps their so called tests.

Just look at how they covered up the SKYTHERM heating/cooling system that costs about $1.00 a year to operate. They barely give lip service to ICF wall systems, and they make incomplete statements about REBs to discourage their use. DOE has too many skeletons and is politically handicaped, severally. The government/DOE has crawled in bed with the ones who will make them the most money.
What? You don't think the government is greedy?

Oh yes, one other thing. How come they use only reflective type insulations on space vehicles?

Thank you for considering my opinion.
 
  #8  
Old 07-31-02, 06:04 AM
Zathrus
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<quote>Just look at how they covered up the SKYTHERM heating/cooling system that costs about $1.00 a year to operate</quote>

Covered up, as in having a HUD grant fund the development of the first Skytherm house in California and then receiving a presidential award in 1976? Ah, that kind of covering up...

Skytherm isn't viable in the vast majority of climates. All of the successful tests occur in hot, arid climates. Although some research has been done in humid climates, I haven't seen any indications that it was effective.

Your $1/year estimate ignores the labor requirements of removing the large roof panels at night and putting them back in place in the morning. (And all of the alternatives to SkyTherm use large amounts of water for evaporative cooling). Nor does it consider the additional costs involved in structural design for having (essentially) a roof pond, or the higher price of large steel sheets for a roof as opposed to plywood, tar, and shingles.

<i>Oh yes, one other thing. How come they use only reflective type insulations on space vehicles? </i>

Uh, maybe because that's the only option? In space you only have heating from radiation. There is no atmosphere, so there's no convective or conductive heating possible. Of course they use thin metal films. When you build a house in space, get back to me. Until then, don't compare apples and oranges.

The only reason I'm taking issue with you is because of the bad science you are spouting off. RB are not 95% efficient. Good ones do, indeed, have a reflectance of 95% or higher, but that does not mean 95% efficient. It ignores that most heating and cooling occurs from convection, not radiation. Housing materials are not good radiators - they have emistivities in the low single digits. A RB does largely eliminate radiant heating, but that is minimal when compared to convective heating. I suspect that conductive heating is a smaller issue than even radiation, but you can't ignore it either -- particularly when you start talking about metal foils which are all good conductors.
 
  #9  
Old 07-31-02, 06:59 AM
rbisys
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Greetings,

Don't want to be disrespectful, but, your comments graffically illustates the old saying " a little knowledge can be dangerous in the wrong hands".

I've talked to Harold Hays (inventor of Skytherm) over the years about this system and he told me about the problems he had with DOE. If you want I'll give you his phone number and you can tell him about your expertize on his system. (He'll love you}

The system was successful in Wis., of all places.

The panels are move by that new fangled energy "electricity". Would you believe?

It's obvious youy have had no "real life" experience with radiant barriers, and your testing experience is now in question. You don't even know the percentages of radiant energy gain/loss in a structure.

Me thinks you're a FG sales man.

Thank you for considering my opinion.

No time for spell ck, sorry.
 
  #10  
Old 08-03-02, 02:26 PM
dsteece
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thanks for the help
 
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